Linux Gazette

Copyright © 1997 Specialized Systems Consultants, Inc.
For information regarding copying and distribution of this material see the Copying License.

Table of Contents Issue #14

The Answer Guy

Weekend Mechanic

TWDT 1 (text)
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 The Mailbag!

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Help Wanted -- Article Ideas

 Date: Mon, 20 Jan 97 13:22:54 EST
Subject: Linux on Compaq
From: afarnsworth@S1.DRC.COM

I just received a brand spanking new Compaq Deskpro 6000 with Adaptec 2940U SCSI card and Compaq Netflex III ethernet card. I think I have the SCSI card problem whipped, but how do I find drivers for the Netflex III card? I have check the usual places, does it even exist?

The Compaq Deskpro 6000 is a fairly new system out, though Compaq has been building Deskpro's for many years. The only problem I have had with them is their proprietary hardware. This is usually either their Network cards or their Hard drive controllers (usually RAID controllers). Other than that, it's pretty standard.

Please reply to my email address : for I don't have the ability to check the gazette often. Thanks.

Andy Farnsworth, Dynamics Research Corporation

 Date: Sat, 18 Jan 1997 12:38:45 +0200 (EET)
Subject: Office-tools From: J.Hernetkoski,

Hi! Could you write an article about these two office-package for Linux:

Jukka Hernetkoski
(An article about StarOffice by Dwight Johnson appeared in issue 9 of Linux Gazette. An article about Applixware will be in the April issue of Linux Journal. I can probably get permission to run it in LG also, but not until that issue of LJ is on the stands. Which means it would also be the April issue of LG. Anyone want to do one sooner?--Editor)

 Date: Tue, 21 Jan 1997 09:43:58 -0500
Subject: Linux samba win95

-I am a system administrator....manages 20 PC's....all running windows95

-We were running Windows NT server(4.0) in the lab for some time Then we realised we had only 10 client access licenses and so were forced tp SWITCH to Linux.

-Linux emulates NT, as you may know

-I had the CONFIG.POL working perfectly with the NT network. -But when I switched to Linux I lost that control. No longer are the clients able to access the CONFIG.POL file even though I have kept it in the NETLOGON share.

-Now whosoever uses the PC's(most are novices) play around with the settings( of client) and is giving me nightmares, since I cannot lock them out.

-Is there a way out? How can I make the clients read the system policies from the CONFIG.POL using Linux server?

Please help.


 Date: Tue, 21 Jan 1997 15:03:07 +0000
Subject: dbms connectivity
From: Mike Lewis,

Hi. I love linux but most of the projects I work on preclude it because of a lack of dbms connectivity. None of the major dbms players (Oracle, Sybase, Informix, etc.) or 3rd party developers (Intersolv, Visigenic, etc.) offer access from a linux client. I've tried a middleware solution from Openlink and I guess you could run SCO drivers with emulation, assuming you can get your hands on the low-level libraries.

This seems to be the only thing standing in the way of Linux getting business worthy respect. Could you put together a piece on this issue and explore the future availability of dbms connectivity from linux?


 Date: Wed, 22 Jan 1997 18:21:57 -0800
Subject: X Windows & Unix
From: Nestor Villalobos,

Hi there! I just got Linux from RedHat and I have been wondering how to do Animations in XWindows. I would like a little picture box on the lower right hand corner of the screen on startup to start an animation. Is this possible? If it is, please email me back with instructions!!! Thanks for the help.

One Unix man to the other,
Nestor Villalobos

General Mail

 Date: Fri, 24 Jan 1997 15:24:16 -0700
Subject: Update web link in my article
From: Henry Lu,

I have changed my web page (email is unchanged). Can you update my web page in the #10 issue, article "setting up a Dynamic web server"?

I got couple of email inquiry about the bad link.


(Be happy to fix it up. We like to stay up to date. --Editor)

 Date: Tue, 21 Jan 1997 13:20:49 -0700
Subject: C++ Programming w/ Linux
From: James Cannon,

About a month ago I asked about help with C++ programming on Linux. I am currently using the Walnut Creek Slackware, kernel 1.3.20. I had a hard time getting a simple "Hello World" program to compile. "cc" couldn't find the ".h" files like "stdio.h", which are normally in /usr/include. I had to create a "$INCLUDE" variable in my ".profile". So, when compiling, I used "g++ -I $INCLUDE -o hello hello.c" to compile.

Well, I received help via e-mail pointing me to this page:
Look for the section titled: Problem Using G++.

Great mag!

James Cannon,

 Date: Thu, 23 Jan 1997 20:36:39 -0800
Subject: Color Depths in X
From: Chris Spiegel,

(RE: Color depths in X)

Well, I know this isn't really a fix, and it's not that great, but I have 2 scripts. startx which starts me in 16 bit color and start8, which starts in 8 bit. As I said, not a solution, but a pretty painless alternative...

 Date: Fri, 3 Jan 1997 17:14:19 -0500 (EST)
Subject: Further note about the spiral notebook page design.
From: Ben Boule,

Someone else noted that his web browser didn't correctly show the spiral notebook background. I use Netscape, so that isn't a problem for me, but I do have another problem with the background. It's very hard to look at on an interlaced display. I can always switch to a non-interlaced mode in XFree86, but I'd bet some people can't. I know that the interlaced mode that I use looks fine on 99.99% of web pages, so it usually isn't a problem for me.

Ben Boule

 Date: Mon, 06 Jan 1997 13:42:25 -0600
Subject: RE: Linux networking problem with VINES
From: Jack N. Gallemore,
To: Stephen,

Unfortunately, Banyan is a pretty tight (read: won't work with much) OS, so you are pretty limited. There is a way for Linux to sign onto Banyan, but you have to use DOSEMU.60.1. The later versions will not work. (Disclaimer: I have not used the patch for dosemu.60.4). If you have not used DOSEMU, the setup is fairly straightforward.

As for using Linux as a resource, you will have to use IP stuff (ftp, telnet, etc) to do so. There are no ports for Linux<->Banyan stuff.

BTW, Jon is still doing Linux and Banyan. His site ( is running Linux! Check it out!

Jack N. Gallemore

 Date: Mon, 20 Jan 97 16:12:00 PST
Subject: Vines IP and TCP/IP
From: Denis Dimick,

Back on Dec 5, 1996 Stefan wrote wanting help with Vines.

Stefan the problem you're having sounds like the Vines Servers are not passing TCP/IP.. By default Banyan Vines doesn't pass route TCP/IP thru the servers. You have to have the TCP/IP option installed on all the servers your going to route thru. This option cost $$$ about $1200.00 US if I remember correctly. So there's p[robally a good chance your school didn't buy this option...

Vines doesn't have anything that will cause IP to tunnel via Vines IP.. So your only chance might be to get access to the same segment that the internet is running off of... But it sounds like your sysadmin is using the Banyan Server as the gateway to the internet, if this is the case your out of luck...

Since I've worked with Banyan Vines for the last 7 years, I'm sorry to say you might not be able to set up the Linux Box on the internet routing thru your Banyan Servers...


 Date: Sat, 11 Jan 1997 11:49:18 -0700
Subject: Linux Applications and Utilities Page
From: David Puryear,

I came across Linux Applications and Utilities Page while I was learning about linux. It helped me get the feel for what is able in linux.

The guy that maintains it is Bill Latura. I hope people will get good use out of it and maybe help it become even more complete:)


(We found it too; see News Bytes. --Editor)

 Date: Tue, 14 Jan 1997 06:06:09 -0800
Subject: isssue 8 & ftp server
From: Rick Lim,

Hi there,
thanks for hosting the gazette. Is there a way of just downloading the text of each issue? I have downloaded LinuxGazette_jan97.tar.gz and it seems that issue8.txt is missing. also I have tried to ftp LinuxGazette_dec96.tar.gz but after 1770k of 2751k the server seemingly goes into ignore mode, this has happened about 5 times.

Thanks again

(Don't know why you are having trouble ftp'ing LinuxGazette_dec96.tar.gz, but can tell you that you have LinuxGazette_jan97.tar.gz you have everything that is in dec96. We took over LG for issue 9, so there is no file issue8.txt or 1 to 7 either. We use Lynx to save the HTML as text. Perhaps we'll do it for 1-8 one day when we have time. --Editor)

 Date: Sun, 26 Jan 1997 17:00:35 -0600
Subject: suggestion
From: dave Stephens,

can you put some thing in each week for the new linux ueser the newbe things

thank you

(LG is posted once a month not weekly. All the material in LG is contributed to me by outside authors. I take whatever I get. A lot of it is geared toward the newbee, and this month we have a new column called "Clueless At the Prompt" by Mike List that is designed for the newbee. Sounds like just what you are looking for. --Editor)


This page written and maintained by the Editor of Linux Gazette,
Copyright © 1997 Specialized Systems Consultants, Inc.

"Linux Gazette...making Linux just a little more lovable!"

More 2¢ Tips!

Send Linux Tips and Tricks to


Backquotes Warning

Date: Tue, 14 Jan 1997 00:40:21 -0800 From: alan bailward

In the $0.02 tip for using the script 'swaplogs' the commands : cp /var/adm/messages /var/adm/messages.'date +%d' uses the wrong quotes. The backquote not the forward quote has to be used here, to make the *output* of the command part of the filename.


(Actually, the backquote is in the html. It's just that some Browser fonts wont print a backquote -- in fact, mine doesn't. I'm not sure how to get around this other than to warn people who are reading online. If you print LG out, the quotes will be in the right direction. --Editor)

WWW Background Tip

Date: Wed, 8 Jan 1997 12:23:03 -0500 (EST)
From: Kurt M. Hockenbury,

I noticed people complaining about backgrounds making text unreadable. Personally, I got tired of unreadable backgrounds, as well as large image downloads, so I turned them off. I also turned off those annoying blink tags.

How? Add these two lines to your ~/.Xdefaults file.

Netscape*documentColorsHavePriority: False
Netscape*blinkingEnabled: False

In LG #13, Eje Gustafsson, writes:

>> /var/adm/messages /var/adm/messages.prev 
>>          2.touch /var/adm/messages 
>>          3.kill -1 pid-of-syslogd 
>>       This should work on a decent Unix(like) system, and I know Linux 
>>is one of them. 
>This is NOT an proper way of truncate /var/adm/messages. 
>It is better to do: 
>  1.cp /var/adm/messages /var/adm/messages.prev 
>  2.>/var/adm/messages or cp /dev/null /var/adm/messages (both of them makes 
>the file empty). 
>  3.No more. 
I'm sorry, but (at least on Linux) this is flat out _wrong_. The first method (mv & HUP) is the correct method of truncating syslog files (such as /var/adm/messages).

Your method looses any messages that get syslog'd between steps 1 and 2; anything that comes in after the first cp gets overwritten when the second cp happens.

>The problem is that when you remove the /var/adm/messages syslogd gets
>confused and unhappy and you have to give syslogd a HUPSIG but if you
>just sets the file length to zero without removing the file syslogd
>don't complain. And if you are really unlucky your system will go down
>because you didn't create /var/adm/messages quick enough or forgot it.
Not so. mv'ing /var/adm/messages doesn't bother syslogd at all, as long as you stay on the same partition. In fact, you can 'mv /var/adm/messages /var/adm/fish', and until syslogd is HUP'd or otherwise restarted, it will keep logging in the file fish. Try it if you don't believe me - it's true! That is because once syslogd has open()d the file, it will keep writing to that file until it close()s it - and a file in the Unix world is an inode, not a filename. (As an aside, this is how you can have the 100% full empty partition. Even though you unlink or rm a file, the file doesn't actually go away until all programs that have it open close it.)

syslogd doesn't get confused at all. You can even rm /var/adm/messages, and syslogd won't crash your system, though eventually the partition may fill up with syslog messages you can't easily read since there isn't a filename associated with the log file anymore.

Kurt Hockenbury, Distributed Systems Administrator
Stevens Institute of Technology

Even Better Lowercasing of Filenames

Date: Sun, 5 Jan 1997 19:17:16 -0800 (PST) From: Greg Badros,

It's even easier with zsh (3.0.x) to convert filenames to all-lowercase:

for i in *(.); mv $i ${i:l}
The *(.) uses a modifier on the wildcard to mean "only regular files" (i.e., not directories). And the ${i:l} converts the variable to lowercase, so we don't have to use tr.

This is not only shorter to type, but doesn't exec multiple programs (test + mv + tr) for each file, and looks at fewer files since the shell implicitly does the first test.


Filtering Advertisements from Web Pages using WebFilter

Date: Thu, 16 Jan 97 20:28:50 PST
From: Axel Boldt,

Hi, In last month's Gazette, David Rudder wrote an article about how to filter advertisements from web pages using IPFWADM, the idea being that many ads come from the same site and it is easy to configure a Linux firewall to refuse all connections from such a site.

This approach has two disadvantages: you have to be root in order to use the IPFWADM tool, and it allows you only to block entire sites. Very often, you want to filter out only a specific ad residing on a site, without blocking the rest of that site's material. Moreover, different users of the Linux box might have different tastes when it comes to ads.

I believe that my tool WebFilter a.k.a. NoShit addresses these issues and is better suited for filtering ads from specific web sites. The idea is the following: the user runs WebFilter as a personal filtering proxy server, and the browser contacts this proxy whenever it wants to fetch a web document. The proxy then actually goes out and downloads the page, checks whether any filterscripts apply to this page, and if yes, pipes it through those scripts and returns the output to the browser. The mapping between URL and filterscript has to be provided by the user in advance. A filterscript can be an arbitrary program that reads the original document from standard input and produces the filtered version on standard output. In practice, filterscripts are most often short sed, awk, or perl scripts.

If you often use sites such as Yahoo or Infoseek, you can easily write filterscripts that excise the ads from their pages. This saves time, money, and bandwidth.

More information about WebFilter can be gotten from its homepage. There you'll also find links to other programs implementing the same idea.

Have fun,

Getting less to View gzipped Files

Date: 09 Jan 1997 20:18:58 -0600
From: Alan Shutko,

A little known ability of less is the ability to define filters when it opens and closes files. This excerpt from the man page deserves broader attention, since it can easily be extended to other types.

For example, on many Unix systems, these two scripts will allow you to keep files in compressed format, but still let less view them directly:

            #! /bin/sh
            case "$1" in
            *.Z) uncompress -c $1  >/tmp/less.$$  2>/dev/null
                 if [ -s /tmp/less.$$ ]; then
                      echo /tmp/less.$$
                      rm -f /tmp/less.$$

                      Version 321: 18 Jul 96                   16

            #! /bin/sh
            rm $2
To use these scripts, put them both where they can be exe- cuted and set LESSOPEN=" %s", and LESSCLOSE=" %s %s". More complex LESSOPEN and LESSCLOSE scripts may be written to accept other types of compressed files, and so on.

Alan Shutko

Help for Help on the Bash Shell

Date: Tue, 14 Jan 1997 15:36:50 +0100 (NFT)

you did hear about help for the bash. if you invoke help for then you will get some help about for.

Okay, you know that one. But did you know you can see all the helps at once? I did not know it. Then I tried help "$*" and what happend was: every help was shown! Of course too much for one screen. so I piped it to less: help "$*" |less is quite good. But then I thought about having a search command with less. possible? yes, just do a less -p word file to see it.

So I put everything together and like I do often I created an alias:

alias helpall="help '$*' | less -p "
and tried it: beautiful, I might not need man bash all the times. Try it yourself.

Perhaps try helpall " let " to see a result.

Have a nice and bright Linux-year!


Lower Your CAPS

Date: Sat, 25 Jan 1997 20:44:42 -0800 (PST)
From: Peat Bakke,

One of those little things that gets to me is unzipping DOS pkzipped files. All of the filenames are in all caps. I'm not sure why it bugs me, but it does. Anyhow, here's a quick script that I've found useful to convert all the caps in a directory into lower case (rather nice when you've got one of those big, 200 file zips):

        foreach i (*)
        mv $1 `echo $1 | tr '[A-Z]' '[a-z]'`
A word to the wise -- this lowers ALL caps, so be careful with those Makefiles and such.


Making Linux Boot Floppies

Date: Sun, 5 Jan 1997 18:40:49 -0800 (PST)
From: Andy Kahn,

After reading Bill Duncan's excellent article in issue #13 on using and managing floppies in Linux, I figured I'd toss in a 2-cent tip.

Here is a script I use to make emergency boot floppies on my system (kernel v2.0.27). The need arose when I installed RedHat 4.0 for the first time and noticed that the installation procedure doesn't automatically prompt you to create boot floppies (Slackware does, and chances are that RedHat will also in the next version).

#!/bin/csh -f
# makebootfloppy v0.2
# User friendly script (with lots of verbose messages) used to make
# Linux boot floppies, using the 2.x kernels.
# Formats, creates the file system, mounts the floppy, installs the Linux
# kernel, installs LILO, umounts floppy, and cleans up.
stty intr 
set PATH=(/usr/sbin /sbin /bin /usr/bin)

# the generic floppy device (usually auto-detected)
set GENFLOPPY=/dev/fd0

# the low-level floppy device, used with fdformat.  this might be obsoleted
# on your system
set LLFLOPPY=/dev/fd0H1440

# a temporary mount point for your floppy.  make sure it has enough space
# to copy the kernel into
set MOUNTPOINT=/tmp/floppy

# boot
set BOOT=/boot/boot.b
set KERNEL=/boot/vmlinuz

# LILO label
set LABEL=linux

# here we go!
echo -n Insert a blank floppy into the drive and hit return...
set FOO=$<

# Low-level formatting the floppy...
fdformat $LLFLOPPY

# Making file system on floppy...
mke2fs -c $GENFLOPPY

# Mount the floppy
mkdir $MOUNTPOINT >& /dev/null

# Copy the kernel to the floppy

# Install lilo
echo image=$MOUNTPOINT/`basename $KERNEL` label=$LABEL | \
    lilo -C - -b $GENFLOPPY -i $MOUNTPOINT/boot.b -c -m $MOUNTPOINT/map


# Unmount floppy

# Deleting temporary mount point

echo All done.

There's currently no error handling, so if one command fails, the remaining commands will fail as well. Other than that, feel free to modify and use it as you like. If you have suggestions on better ways to do something, I'd love to hear them.

More on Xterm Titlebar Tip

Date: Wed, 15 Jan 1997 23:33:34 -0700 (MST)
From: Michael J. Hammel,

I got a lot of email about my tip, most confused by the use of escape/control characters in the script. Here is my response.

> > Date: Sat, 21 Dec 1996 15:18:01 -0600
> > From: Roger Booth 
> > To: Linux Journal Editor
> > 
> > The Jan97 Issue 33 of Linux Journal contained the "Linux Gazette Two Cent Tips". 
> > I was interested in the tip "X Term Titlebar Function". Although 
> > the text of the tip stated that the tip would work in ksh-based 
> > systems, I could not get it to work as shown. I think there are 
> > three problems. First, I think there are a few transcription 
> > errors in the script. Second, I believe the author is using 
I don't think there were transcription problems. I'm pretty sure it was the way I sent it, however....
> > embedded control characters and it was not obvious to me which 
> > character sequences are representations of control characters 
> > and which characters should be typed verbatim. Third, the 
Yes, there were control and escape characters in the file. This was a problem and many people wrote me to ask about it. In the following lines:
   ilabel () { echo -n "^[]1;$*^G"; }
   label () { echo -n "^[]2;$*^G"; }
the characters "^[" are an escape character and the characters "^G" are a CONTROL-G character. In order to add these to your file (when you type it in by hand) using vi you would type:

^VESC - which means CTRL-SHIFT-V followed by the ESCAPE key


^V^G - which means CTRL-SHIFT-V followed by CTRL-SHIFT-G

Note that in *this* email I didn't actually include the control or escape characters - I simply used their ASCII equivalents. Hopefully this isn't too confusing.

> > author uses a command-line option to the echo command which 
> > is not available on all Unix platforms.
This is also a problem. See below.
> > I finally used the following script:
> > 
> >     if [ ${SHELL##/*/} = "ksh" ] ; then
> >         if [[ $TERM = x"term" ]] ; then
> >             HOSTNAME=`uname -n`
> >             label () { echo "\\033]2;$*\\007\\c"; }
> >             alias stripe='label $LOGNAME on $HOSTNAME - ${PWD#$HOME/}'
> >             cds () { "cd" $*; eval stripe; }
> >             alias cd=cds
> >             eval stripe
> >         fi
> >     fi
> > I don't use vi, so I left out that functionality.
I tried this and various similar responses that were mailed directly to me. It should work using the octal versions of the escape sequences, but I couldn't get it to work. My problem is that I use the label() function from the command line at times to simply set the title bar to some arbitrary value and using the octal sequences didn't seem to work for me. I'm not sure why, however. I do believe that, sometime in the distant past, I too used octal sequences to set the xterm title bar. I've long forgotten why I switched.
> > The functional changes I made are all in the arguments to the 
> > echo command. The changes are to use \\033 rather than what 
> > was shown in the original tip as ^[, to use \\007 rather than 
> > ^G, and to terminate the string with \\c rather than use the 
> > option -n.
All of these should work just fine in ksh. Your observation that not all shells accept "echo -n" is correct. I often have to check which works and then manually set the echo line to either use "-n" or to print a \c. One or the other will always work, depending on if the echo is a shell builtin or an actual Unix command.
> > On AIX 4.1, the command "echo -n hi" echoes "-n hi"; in other 
> > words, -n is not a portable command-line option to the echo 
> > command. I tested the above script on AIX 3.2, AIX 4.1, 
> > HPUX 9.0, HPUX 10.0, Solaris 2.4 and Solaris 2.5. I'm still 
> > trying to get Linux and my Wintel box mutually configured, 
> > so I haven't tested it on Linux.
I don't use X on the AIX or HPUX boxes at work. I just rlogin from my Sun boxes. However, both Solaris and Linux should work with the -n option if you're using the echo shell builtin. If not, the \c will probably be required. On my Linux box I type
   bash% type echo
which reports
   echo is a shell builtin 
so I know which one I'm using. Knowing this you can provide alternatives within your .bashrc or .kshrc to determine which version of the echo line to use. This is true of any Unix platform on which you use ksh or bash (I believe).
> > I have noticed a problem with this script. I use the rlogin 
> > command to log in to a remote box. When I exit from the
> > remote box, the caption is not updated, and still shows the 
> > hostname and path that was valid just before I exited. I tried
> > adding
> > 
> >     exits () { "exit" $*; eval stripe; }
> >     alias exit=exits
> > 
> > and
> > 
> >     rlogins () { "rlogin" $*; eval stripe; }
> >     alias rlogin=rlogins
> > 
> > Neither addition updated the caption to the host/path 
> > returned to. Any suggestions?
Add this right after the alias for cd in the original script:
   rlogins () { "rlogin" $*; cds . }
        alias rlogin=rlogins
Its a hack, but it works. You have to use "cds" instead of the alias "cd" or else the real cd gets used and the title bar won't change. In case anyone is wondering, the reason you enclose "rlogin" (or "cd" or "vi") in double quotes in this script is so the function rlogins() will run the real rlogin and not get stuck recursively calling itself. Neat, eh?

Boy, this stuff could get confusing fast. Maybe it wasn't such a good tip after all.

Michael J. Hammel

Remind Tip

Date: Mon, 20 Jan 97 15:42:04 PST

This is a nice little script wich I have made, it places reminders to ~/.tcshrc or whatever. I think it's very useful. To use it first place at THE END OF ~/.tcshrc:

echo "--------------------( R E M I N D E R S )--------------------"
echo "-------------------------------------------------------------";\echo
Then use this script:
# Nice little scipt that places reminders to the end of ~/.tcshrc or
# Made by email if you like it!

echo Remind 1.0 by
if ($#argv == 0) then
echo Use like \'remind \
echo Option is \'a\' for add , \'u\' for undo and \'r\' for remove, pretty
exit 666
if ($argv[1] == a) then
cat ~/.tcshrc | awk '\!/-------\";\\echo/ { print }' >! /tmp/remind.$user
echo echo $argv[2-] >> /tmp/remind.$user
echo 'echo "-------------------------------------------------------------";\echo'
>> /tmp/remind.$user
cp ~/.tcshrc ~/.tcshrc.remind
rm -f ~/.tcshrc
mv /tmp/remind.$user ~/.tcshrc
echo Added reminder: $argv[2-]
else if ($argv[1] == r) then
cat ~/.tcshrc | grep -v "echo $argv[2-]" >! /tmp/remind.$user
cp ~/.tcshrc ~/.tcshrc.remind
rm -f ~/.tcshrc
mv /tmp/remind.$user ~/.tcshrc
echo Removed Reminders:
diff ~/.tcshrc ~/.tcshrc.remind | awk '$2 ~ /echo/ { print$3,$4,$5,$6,$7,$8,$9, 
$10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$20,$21,$22,$23,$24,$25 }'
else if ($argv[1] == u) then
if (-e ~/.tcshrc.remind) then
mv ~/.tcshrc ~/.tcshrc.remtemp
mv ~/.tcshrc.remind ~/.tcshrc
mv ~/.tcshrc.remtemp ~/.tcshrc.remind
echo Undo completed
echo No undo file was found \(~/.tcshrc\)
echo Error: invalid argument\(s\) run it with no argument for a short help
exit 666
Dont forget to do a 'chmod a+x remind' And NEVER place any new lines after the lines you placed in ~/.tcshrc If you wan't to use it with some other shell it should just be like changing the paths in the script. And yes, it maybe should have been alot easier to put the reminders in a separat file, but i like this solution i'ts alot cooler...and maybe it can show someone how awk works.

Script to Call Your Editor

Date: Thu, 16 Jan 97 15:21:34 PST
From: Gary Chambers,

I just found the Linux Gazette... Thankfully! It has truly made using Linux more fun.

I use the Linux version of Marko Macek's FTE editor. Since it is comprised of a separate X and console version, I began to get frustrated with having to manually specify a default editor. Now, wherever I can specify it (e.g. Pine), I use my edit script. It also provides similar functionality at the command line.

I'm new to Linux, so there may be better ways of doing this. I submitted this for inclusion in your 2-cent tips (my favorite section).


# Determine whether we're in X Windows and call the proper editor

if [ "$WINDOWID" = "" ]; then
        fte $1 $2 $3 $4 $5
        xfte $1 $2 $3 $4 $5
GeeCee, Gary Chambers

Tip for Your Web Page

Date: Fri, 3 Jan 1997 17:26:14 -0500 (EST)
From: Ben Boule,

One cool tip that I have found useful is the following. If you are running your web page on your own machine or have the directory on NFS, put the following in your .profile :

cp ~/.netscape/bookmarks.html ~/public_html/bookmarks.html
cp ~/lynx_bookmarks.html ~/public_html/bookmarks2.html

Change for different browsers and server setups.

Then you can link them on your web page, and they get updated every time you log in, start a new xterm, etc...

Of course, this assumes you don't care about other people looking at your bookmarks.

Ben Boule

Re: Titlebar Tip

Date: Mon, 20 Jan 1997 18:40:38 +0200 (SAT)
From: Christopher Gordon,

Roger Booth sent in a corrected version of the Titlebar script. I found that in order to get this working on a Slackware distribution of Linux, using the bash shell, further modifications were neccesary. The control characters need one \ as opposed to \\. The "echo" command required an -e switch. The "if" statement only needed one [] not two. Finally, the script needed to check if "bash" was running or not. I also added a command to simplify the prompt. Here is the corrected script. It can be run using the source command.

if [ ${SHELL##/*/} = "bash" ] ; then
         if [ $TERM = x"term" ] ; then
             HOSTNAME=`uname -n`
             label () { echo -e "\033]2;$*\007\c"; }
             alias stripe='label $LOGNAME on $HOSTNAME - ${PWD#$HOME/}'
             cds () { "cd" $*; eval stripe; }
             alias cd=cds
             eval stripe
             export PS1='\$ '
Standard disclaimers apply.

Christopher Gordon,
Remote Sensing, Inst. for Soil, Climate and Water
Pretoria, South Africa

Two Bit Tip -- Heartbeat

Date: Wed, 22 Jan 1997 22:29:06 -0800 (PST)
From: Kragen Sittler,

#!/bin/sh # This is a shell archive (produced by GNU sharutils 4.1). # To extract the files from this archive, save it to some FILE, remove # everything before the `!/bin/sh' line above, then type `sh FILE'. # # Made on 1997-01-22 22:11 PST by . # Source directory was `/usr/local/heartbeat'. # # Existing files will *not* be overwritten unless `-c' is specified. # # This shar contains: # length mode name # ------ ---------- ------------------------------------------ # 2222 -rw-r--r-- README # 102 -rw-r--r-- crontab # 371 -rwxr-xr-x heartbeat # 142 -r-xr-xr-x rc.heartbeat # 1045 -rwxr-xr-x update.sessionid # touch -am 1231235999 $$.touch >/dev/null 2>&1 if test ! -f 1231235999 && test -f $$.touch; then shar_touch=touch else shar_touch=: echo echo 'WARNING: not restoring timestamps. Consider getting and' echo "installing GNU \`touch', distributed in GNU File Utilities..." echo fi rm -f 1231235999 $$.touch # # ============= README ============== if test -f 'README' && test X"$1" != X"-c"; then echo 'x - skipping README (file already exists)' else echo 'x - extracting README (text)' sed 's/^X//' << 'SHAR_EOF' > 'README' && Heartbeat package X My computer seems to crash often -- about once every ten days. I've been wanting to know when this happens, but since the computer is busily crashing, it doesn't have time to tell me. (I suspect this happens because of power outages.) X So I wrote a simple heartbeat package, which would keep a record in the filesystem when it was alive. That way, I could look at this record when the machine crashed and tell when and how long it had crashed. X So I wrote a few scripts and created a new user. I named the heartbeat user 'heartbeat'. (I know it's not really kosher to have a nine-letter username, but the only thing that has problems with it so far is ls.) X heartbeat is the first script; it updates a file in /var/log/heartbeat. X Here's the meat of heartbeat. X X #!/bin/sh X touch /var/log/heartbeat/"`cat /var/run/heartbeat.sid`" X /var/log/heartbeat should be writable and executable by the heartbeat user; you may want to use root. heartbeat gets run once a minute on my system, from the heartbeat's crontab: X * * * * * /usr/local/heartbeat/heartbeat X (For some reason, my crond does not like whitespace before crontab entries.) X The name of the file it updates is taken from /var/run/heartbeat.sid. (I'm not sure /var/run is really an appropriate place to put this, but I couldn't find a better place.) This file should be readable and writable by the heartbeat user. X heartbeat.sid is updated at boot time by a Perl script called update.sessionid. update.sessionid also puts some information in the file that heartbeat updates. X I run update.sessionid (as the heartbeat user) from /etc/rc.d/rc.M, just before cron is started. X Here's the section from my rc.M: X X.... # # Update heartbeat sessionid. # This helps us find out when there was a crash. [ -x /etc/rc.d/rc.heartbeat ] && /etc/rc.d/rc.heartbeat X # Start crond (Dillon's crond): X.... X and here's /etc/rc.d/rc.heartbeat: X #!/bin/sh # Update the heartbeat sessionid. # This should be done before starting cron. su heartbeat -c /usr/local/heartbeat/update.sessionid X Now, when I want to know when the machine crashed, I can look in /var/log/heartbeat for the times of system shutdowns -- planned or otherwise. SHAR_EOF $shar_touch -am 0122221197 'README' && chmod 0644 'README' || echo 'restore of README failed' shar_count="`wc -c < 'README'`" test 2222 -eq "$shar_count" || echo "README: original size 2222, current size $shar_count" fi # ============= crontab ============== if test -f 'crontab' && test X"$1" != X"-c"; then echo 'x - skipping crontab (file already exists)' else echo 'x - extracting crontab (text)' sed 's/^X//' << 'SHAR_EOF' > 'crontab' && # MIN HOUR DAY MONTH DAYOFWEEK COMMAND * * * * * /usr/local/heartbeat/heartbeat SHAR_EOF $shar_touch -am 0122221197 'crontab' && chmod 0644 'crontab' || echo 'restore of crontab failed' shar_count="`wc -c < 'crontab'`" test 102 -eq "$shar_count" || echo "crontab: original size 102, current size $shar_count" fi # ============= heartbeat ============== if test -f 'heartbeat' && test X"$1" != X"-c"; then echo 'x - skipping heartbeat (file already exists)' else echo 'x - extracting heartbeat (text)' sed 's/^X//' << 'SHAR_EOF' > 'heartbeat' && #!/bin/sh # script to continually update a file's timestamp, except when the machine # is down # # This should be put in a crontab to be run every minute, or five minutes, # or whatever. # # /var/run/heartbeat.sid contains a sessionid that is incremented at each # bootup, and is suitable for use as a filename. X touch /var/log/heartbeat/"`cat /var/run/heartbeat.sid`" SHAR_EOF $shar_touch -am 0122210097 'heartbeat' && chmod 0755 'heartbeat' || echo 'restore of heartbeat failed' shar_count="`wc -c < 'heartbeat'`" test 371 -eq "$shar_count" || echo "heartbeat: original size 371, current size $shar_count" fi # ============= rc.heartbeat ============== if test -f 'rc.heartbeat' && test X"$1" != X"-c"; then echo 'x - skipping rc.heartbeat (file already exists)' else echo 'x - extracting rc.heartbeat (text)' sed 's/^X//' << 'SHAR_EOF' > 'rc.heartbeat' && #!/bin/sh # Update the heartbeat sessionid. # This should be done before starting cron. su heartbeat -c /usr/local/heartbeat/update.sessionid SHAR_EOF $shar_touch -am 0122221197 'rc.heartbeat' && chmod 0555 'rc.heartbeat' || echo 'restore of rc.heartbeat failed' shar_count="`wc -c < 'rc.heartbeat'`" test 142 -eq "$shar_count" || echo "rc.heartbeat: original size 142, current size $shar_count" fi # ============= update.sessionid ============== if test -f 'update.sessionid' && test X"$1" != X"-c"; then echo 'x - skipping update.sessionid (file already exists)' else echo 'x - extracting update.sessionid (text)' sed 's/^X//' << 'SHAR_EOF' > 'update.sessionid' && #!/usr/bin/perl # Update sessionid for heartbeat, creating new sessionid file. # This should be run at boot time. X my $sessionidfile = "/var/run/heartbeat.sid"; my $heartbeatdir = "/var/log/heartbeat"; X open SESSIONIDFILE, $sessionidfile or X die "Couldn't open <$sessionidfile> for read"; X my $sessionid = ; close SESSIONIDFILE; chomp $sessionid; X if ($sessionid !~ /^[a-zA-Z]*[0-9]{4,}$/) { $sessionid = "boot0000"; } X $sessionid ++; X open SESSIONIDFILE, ">$sessionidfile" or X die "Couldn't open <$sessionidfile> for write"; X print SESSIONIDFILE "$sessionid\n"; close SESSIONIDFILE; X my $heartbeatfile = "$heartbeatdir/$sessionid"; X open HEARTBEATFILE, ">$heartbeatfile" or X die "Couldn't open <$heartbeatfile> for write"; X my $message = <<$heartbeatfile> failed after open; fs full? stopped"; X close HEARTBEATFILE; X Xexit 0; SHAR_EOF $shar_touch -am 0122211997 'update.sessionid' && chmod 0755 'update.sessionid' || echo 'restore of update.sessionid failed' shar_count="`wc -c < 'update.sessionid'`" test 1045 -eq "$shar_count" || echo "update.sessionid: original size 1045, current size $shar_count" fi exit 0

2 Cent Tip for xdm

Date: Sun, 5 Jan 1997 21:28:02 -0600 (CST)
From: Andrew Dyer,

here are several ways you can dress up an xdm login screen:

  1. use the 'Xbanner' program available on sunsite
  2. run a program like xearth or xfishtank that writes to the X login screen background
  3. use a static image display program like 'xv' to put up a simple bitmap
I use xv to put up an image - to do this add a line like the following to the file /usr/X11R6/lib/X11/xdm/Xsetup_0 (at least that's where is is in my system (Caldera)):

/usr/X11R6/bin/xv -rmode 1 -nc 64 -quit /home/adyer/pics/arcade.bmp

This line will run 'xv' to put the image file at the end of the command line onto the background window in 'root tiled' mode, dithers the image to only use 64 colors (to preserve colormap slots on my 256 color display), and tells xv to exit after doing this.

Note that if you run a program like xearth it will continue to run after you have started the session and will contiinue to run by default until the session is exited. See the 'xdm' man page for more details.

!!!!!!!!!!!!! !! WARNING !! !!!!!!!!!!!!!

programs run by xdm are usually run as root, and so pose a potential security risk if they are not specifically designed for this. You have been warned :-)

Andrew M. Dyer

Two 2 Cent Tips -- syslog & X Color Depth

Date: 13 Jan 1997 10:33:29 +0100
From: Marco Melgazzi,

Dear sirs

Here's two 2c tips for your wonderful Linux Gazette. Note that all the lines ending with \ have to be joined on one line.

1. :::: Syslog fun (oh no, not again) :::::

Everybody seem to like to put a line like the following in their syslog:

        *.*  /dev/ttyx
this way every message is printed on an unused tty and the curious ( or worried ) user can switch to it and see what's going on. This approach has a big advantage ( it doesn't use any system resource ) and a couple of disadvantages ( notably you have to switch to text mode to read the messages and then you don't have scrollback ). So I have this little workaround: in /etc/syslog.conf put something like
        *.*                     /var/adm/current_session_log
In rc.local or whatever file is called before starting syslog
        /bin/cat /dev/null > /var/adm/current_session_log
In fvwm you can add something like this:
Style "tail" NoTitle, NoHandles, Sticky, WindowListSkip
Style "tail" StaysOnTop, CirculateSkip

*GoodStuff              S-Log   telnet-sm.xpm           Exec "rxvt" \
                        rxvt -geometry 132x45-0+0 -sl 1200 -font fixed \
                        -e tail -n 1200 -f /var/adm/current_session_log &
So when you press the goodstuff button named 'S-log' you get a big rxvt with a nice scrollback buffer that displays exactly what's going on in the system. If your linux system stays up for weeks at a time you'll probably have to set up a CRON entry that trims this file every once in a while but this is left as an exercise for the reader ;-)

To pop down the rxvt a simple Ctrl-C is more than enough. By the way, this approach will surely save a lot of stress to the monitor electronics: in fact switching from text mode to hires a) takes time b) involves quite a lot of non-trivial adjustments in the monitor circuitry so it could likely acceelerate its ageing process.

2. ::::: How to use X with more than one color depth ::::::

I normally use X in 8bit ( since my board is not VRAM based 1152x864 at 70Hz slows down things considerably ) but, since when I hacked my XF86_S3 to let me use higher clocks in 16bit mode :), occasionally I need to switch to the 16bits depth (notably when using the oh-so-amazing 'The Gimp').

Since leaving two servers up and running all the time via xdm seemed a waste of memory, by tinkering with manual pages and articles from the net I came up with a viable alternative.

Let me first tell you one thing: in this way, when the second server is running, you get both :0 (in 8bit) that is managed by xdm and :1 that has been started on-demand. Since I don't usually use :1 while I'm online I didn't took the time to provide MIT-MAGIC-COOKIE authorization for it: this is a thing you -should- do if you plan to use this on the net.

Here there are a couple of my scripts:

::: ----------------------------------------------------------------
::: ----------------------------------------------------------------
xinit ~/.x_rc_for_1_16  -- /usr/X11/bin/X16 :1 vt8 &

::: ----------------------------------------------------------------
::: ----------------------------------------------------------------
exec -bpp 16 ${@+"$@"}

::: ----------------------------------------------------------------
::: ----------------------------------------------------------------
# $XConsortium: xinitrc.cpp,v 1.4 91/08/22 11:41:34 rws Exp $


export PATH= .... path ....

# merge in defaults and keymaps

if [ -f $sysresources ]; then
    xrdb -merge -display :1 $sysresources &

if [ -f $sysmodmap ]; then
    xmodmap -display :1  $sysmodmap &

if [ -f $userresources ]; then
    xrdb -merge -display :1  $userresources &

if [ -f $usermodmap ]; then
    xmodmap -display :1  $usermodmap &

misc other variables

exec fvwm -f .fvwmrc_for_1_16

::: ----------------------------------------------------------------
::: in ~/.fvwmrc_for_1_16 I have this: I'm not sure this duplication
::: is necessary but in my configuration it is. YMMV
::: ----------------------------------------------------------------
Function "InitFunction"
    Exec    "I"     xrdb -display :1 -merge ~/.Xresources &
    Exec    "I"     xmodmap -display :1 ~/.Xmodmap &
        Module  "I"             GoodStuff
        Exec    "I"         emacs &
In this way when you execute the 1open16 script you will get a 16bit screen on :1 at the default resolution you put in your system XF86Config for 16bit depth.

Things get a little more hairy if you want to open the new screen with a different set of resolutions: unluckily ( I guess for security reasons ) XFree lets you use a new XF86Config -only- if you are root. So to play Quake on :1 you have to do the following...

::: ----------------------------------------------------------------
::: in ~/.fvwmrc ( this is nice for password requests, I use it all the
::: time, just put the word 'Password' in the rxvt that you need and use
::: the supplied style. I use it for going online, to access netscape &
::: other net stuff ( I'm paranoid so I created a user named -net- that
::: I use for all internet related stuff, I hate live-data trojans etc.)
::: you get the point.)
::: ----------------------------------------------------------------
Style "*Password" NoTitle, NoHandles, Sticky, WindowListSkip,StaysOnTop

::: in a menu entry
Exec    "Quake (normal)"                exec rxvt -fn \
        "-b&h-lucidatypewriter-medium-r-*-*-*-180-75-75-*-*-*-*" \
        -geometry 40x1+1-1 -T \"Quake Password" -e \
        su root -c "/home/marco/bin/qk" &

::: ----------------------------------------------------------------
::: /home/marco/bin/qk. The redundant su is needed if you plan to launch
::: this file from the command line too.
::: ----------------------------------------------------------------
cd /home/marco/quake
su -c "xinit ./xf86quake  -- /usr/X11/bin/X -bpp 8 :1 vt8 -xf86config \
Of course /home/marco/lib/XF86Config.quake will contain only the resolution that I usually play quake at ( that is 400x300 or 512x384 ). In this way you can play quake without hassless even if you usually run at 1000-or-so x 800-or-so at whatever depth. Now if only Linus released the updated 1.06 xf86quake ;-) (in 1.01 you can't use a custom heap, you have the fixed 8mb one :( ).

Hope you'll like these tips!

Marco Melgazzi

X Windows Color Depth

Date: Fri, 17 Jan 1997 08:38:20 -0500 (EST)
From: Aaron B. Dossett,

>I have recently been messing with my x-server, and have managed >to get a depth of 16, ie 2^16 colors. This works >really nice with Netscape, but some programs (doom, abuse, and >other games) wont work with this many colors. Do >you know of a fix? I have tried to get X to support multiple >depths--to no avail. The man-page suggests that some >video cards support multiple depths and some don't. How do I know >if mine does.
Well, if your video card has enough RAM and you've got enough modes defined in your XF86Config file then you can specify the bit depth from the command line. If you have a link called X to the server then the command
  X -bpp 8 or X -bpp 16 or X -bpp 24
can be used. I like to alias the commands X8, X16, and X24 to the above. For this to work best you should have your XF86Config file setup so that each mode uses the maximum resolution possible.

Aaron Dossett,


This page maintained by the Editor of Linux Gazette,
Copyright © 1997 Specialized Systems Consultants, Inc.

"Linux Gazette...making Linux just a little more lovable!"

News Bytes


News in General

 Linux Gazette Italian Edition

Date: Fri, 10 Jan 1997 14:42:52 +0100
The first issue of the Italian Edition of the Linux Gazette, is now available on our site, It is in the spirit of helping italian Linux users and, naturally, this italian edition is under the copying license of your original Linux Gazette.

Bye (and many many thanks!)
Francesco De Carlo,
CICCIO-X, LUGBari Coordinator

 Linux Advocacy mini-HOWTO

Date: Sat, 11 Jan 1997 11:53:19 +0100 (MET)
This is the Linux Advocacy HOWTO and is intended to provide guidelines and ideas to assist with your Linux advocacy efforts. -- authored by Paul L. Rogers,

Related Links:
Lars Wirzenius also has some thoughts about Linux advocacy.

The Linux Advocacy Project's goal is to encourage commercial application developers to provide native Linux versions of their software.

 Linux in the News

Linux was chosen by PC Week as part of its list for the top ten products of 1996. See the December 16, 1996 issue. The same issue has a related article about Linux and the Internet.

 Linux Sites to Check Out
This site contains anecdotal references about the commercial applications of Linux. Example uses of Linux in various industries, fulfulling various tasks are listed. Includes form / CGI script that visitors can use to enter data about their own commercial Linux sites.
-- Idan Shoham,
The Linux Applications and Utilities List is an organized collection of pointers to the WWW home pages of over 600 different Linux compatible application programs, system admin tools, utilities, device drivers, games, servers, programming tools, file, disk and desktop managers, internet apps, and more. The January 8 edition has added links to over 80 new programs, as well as corrections to numerous existing listings. -- Bill Latura,
This site is a Linux Support, Information, and general purpose Linuxer Hangout Site -- a meeting place for people interested in learning more about Linux, providing help to other Linuxers, and promoting Linux!!! -- Peter Lazecky,

 PNG Article (see issue13) Update

Apparently Netscape has finally committed to supporting PNG in Navigator and actually made public statements to that effect at its Internet Developers' Conference last October, although there's no indication of it anywhere on their web site. The only question is when: Navigator 4.0 has a fixed release date, and PNG support may not be ready by then.
-- Greg Roelofs,

 Rochester, Revised OS Seminar Series Schedule

Date: Sun, 12 Jan 1997 02:36:18 GMT
Computer Science House at Rochester Institute of Technology Presents: an Operating System Seminar Series Wednesday evenings at 8:00PM. Attendance is free of charge and is open to the public.

For additional information, directions, comments or if you would like to be a guest speaker, e-mail .
Computer Science House, ,

 Linux CD Giveaway List

Date: Mon, 13 Jan 1997 05:16:52 GMT
If you have a spare Linux CD to give away, you can list your email address at

Interested parties will contact you, then send in a self-adressed stamped envelope and you send them the CD.

If you would rather (or in addition) lend a Linux CD locally, you can now specify that as well.

For additional information:
Axel Boldt, ,
Univ of California at Santa Barbara, Dept of Mathematics

 Linux Browser Project - A New WWW Browser for Linux

Date: Tue, 14 Jan 1997 06:34:56 GMT
Announcing the Linux Browser Project -- a group of developers developing a world wide web browser for Linux and other platforms. The goal of this project is to develop a web browser which consists of a modular program architecture based around a small, fast kernel which would load necessary modules on demand.

The project is in its early stages, and we are announcing the project at the moment to make ourselves known to the rest of the Linux community. If anyone would be interested in helping us out in any way, please feel free to join the mailing lists or visit the web site and let us know that you are willing to help. For additional information:
See the Linux Browser Project home page at
Jason A. Miller, Project Coordinator,
The Linux Browser Project Team

Software Announcements

 Xfmail 1.0 - mail program for X

Date: Sun, 05 Jan 1997 00:59:12 GMT
Xfmail 1.0 is finally out! XFMail is an X-Windows application for sending and receiving electronic mail. It uses the XForms GUI library toolkit by T.C. Zhao and Mark Overmars.

It has a user-friendly interface and online help to make it easy to use. It implements most of the mail functionality in one program and it does not require any additional tools.

You can ftp XFMail at:

For additional information:
Jacek Bochenek,
Organization: COIG S.A.

 ImageMagick 3.7.9 ELF binaries - general image manipulation tool

Date: Sun, 05 Jan 1997 00:59:19 GMT
ImageMagick (TM), version 3.7.9, is a package for display and interactive manipulation of images for the X Window System.

ImageMagick supports also the Drag-and-Drop protocol form the OffiX package and many of the more popular image formats including JPEG, MPEG, PNG, TIFF, Photo CD, etc.

You will also need the package libIMPlugIn-1.0-elf to get it working. Here are the locations you can get the packages from:

Site: /pub/Linux/X11/xapps/graphics 942k ImageMagick-3.7.9-elf.tgz 1k ImageMagick-3.7.9-elf.lsm 886k libIMPlugIn-1.0-elf.tgz 1k libIMPlugIn-1.0-elf.lsm
For additional information:
Alexander Zimmermann, ,
Organization: Universitšt Passau

 Visual Tcl 1.07 Beta

Date: Sat, 11 Jan 1997 02:42:27 GMT
Visual Tcl 1.07b is a quality application development environment for UNIX, Windows and Macintosh platforms. Visual Tcl is written entirely in Tcl/Tk and covered by the GNU General Public License.

Please choose the location nearest you since my connection can become saturated at peak times.

Home Site: Australia: United Kingdom: Germany: US East: US Mid:
For additional information:
Stewart Allen,

 NExS 1.3-BETA X-Windows spreadsheet now available

Date: Mon, 13 Jan 1997 05:16:23 GMT
X Engineering Software Systems (XESS Corp.) announces the immediate availability of the BETA version of the NExS 1.3 spreadsheet for Linux and UNIX workstations.

NExS, the Network Extensible Spreadsheet, is a full-featured, graphical spreadsheet developed specifically for UNIX and the X Window System. NExS has more than 237 built-in business and scientific functions, allows user-customized functions, displays data using 2 and 3 dimensional graphs, and imports and exports data in a wide variety of formats (including HTML tables).

Demonstration copies and additional conNExions plug-ins may be downloaded from NExS is priced at $149 for the Personal Edition, and $249 if a floating license is desired. For addtional information:

Vnet Internet Access, Inc. - Charlotte, NC.

 PHT Releases Red Hat 4.0

Date: Tue, 14 Jan 1997 06:35:52 GMT
Pacific HiTech is proud to announce the release of our newest Linux product for the i386 architecture:

Turbo Linux: Red Hat 4.0

It features a modular 2.0.18 kernel, better networking, more packages, and, of course, the floppy-less install. The second CD contains the entire contrib/ directory from (the Live Filesystem was scrapped in order to put the contrib/ directory on, which we felt would be more useful for more people).

The 2 CD set is only $19.95 plus s/h. If you want more details on the product, visit

For additional information:
Scott M. Stone,
Chief Linux Developer/UNIX SysAdmin for Pacific HiTech, Inc.

 PHT Releases MkLinux DR2

Date: Tue, 14 Jan 1997 06:35:56 GMT
Pacific HiTech is proud to announce our newest Linux offering for the PPC architecture:

MkLinux DR2 is the latest pre-release version of MkLinux, and it is MUCH MUCH better than DR1 - more stable, more hardware support, and a much smoother installation. It was uncompressed from the FTP distribution and burned as a Macintosh HFS format CD - you don't need to decompress the files onto your hard drive, you can just put in the CD and GO.

It's only $19.95 plus s/h. See for ordering information, or email

For additional information:
Scott M. Stone,
Chief Linux Developer/UNIX SysAdmin for Pacific HiTech, Inc.


This page written and maintained by the Editor of Linux Gazette,
Copyright © 1997 Specialized Systems Consultants, Inc.

"Linux Gazette...making Linux just a little more lovable!"

The Answer Guy

By James T. Dennis,


 Netscape Mail Block

Date: Sun, 15 Dec 1996 23:16:10 -0800 (PST)

hi... mitch here in mobile, alabama...
i need to refuse to accept email from a particular person... how can i configure netscape and/or cnd1.0 to bounce the person's mail back to them?

 I'd use procmail. CND uses procmail as your "local delivery agent" (by default). This means that sendmail passes any mail to a local account to procmail and lets procmail due the final delivery to your mail box (/var/spool/mail/$YOUR_LOGIN_NAME).

However, when procmail does this, it checks for a .procmailrc file in your home directory (and does some ownership and permissions checks on it for you).

procmail is a little programming language specifically for processing mail.

Your .procmailrc file can have a variety of settings and clauses (which are called "recipes" by the author). You can also modularize this by using a variety of INCLUDE directives. Here's a simple example that should get you started.

:0 hr
* ^From.*
* !^X-Loop: ${USERNAME}@`hostname`"
| (formail -r -A"X-Loop: ${USERNAME}@`hostname`" \
   -A"Precedence: junk" ;\
   echo "Your mail is not welcome here."
   echo "Please don't mail me again."
   cat ~/your.signature.or.flame
The :0 marks this as a new recipe (so each new recipe starts with a :0 line). The 'h' on that line is one of several flags to procmail about what parts of the message to hand to your action line (which comes up later). 'h' says: give me the header 'r' says: treat the incoming data as "raw" (so his failure to put a blank line at the end of his message won't cause your response to fail).

The four "star" lines after that are conditions -- the first specifies that the header indicates that the message be "from" your spammer (or unwanted sender). This will actually match any "from" or "From:" line that contains your targets e-mail address. The next two lines try to ensure that you don't respond to daemons and mailers (mailing lists). The next one (which you should fill in with your username and hostname) makes sure that your don't respond to your own response.

Those three conditions are to protect your script from being tricked into doing bad things. Consider them to be the minimum overhead on any autoresponders that you write.

The next line (starting with a "|" pipe character) is the action to take.

In procmail there are three types of actions. A filename simply specifies an mbox (elm, pine, or mailx compatible) folder to file this away in. A directory name specifies an mh or mmdf folder to store the message in (mh and mmdf use different naming schemes for the messages in their folder directories -- you don't need to worry about this unless you use on of these mail user agents). A '!' (bang) line specifies an e-mail address to which to bounce the message. A '|' (pipe) line specifies that the message should be filtered through a local program.

formail is a program that comes with the procmail package. It "formats mail headers." This particular formail command formats a "reply" (-r) header and adds two additional header lines -- a standard "Precedence: junk" line and a personal "X-" line (which the RFC822 spec allows you to use to embed custom information into a header). This is where your message adds the line that would prevent an attack by routing your response back into your script (a mail loop).

The echo and cat statements after the formail line just provide output that is appended after the mail header. This becomes the body of your response. You can add additional echo lines -- or you can create a file and just 'cat' it here.

If you are new to procmail (which is almost certain given your question -- autoresponders are some of the first things procmail'ers learn) you may be nervous about 'breaking' something and losing some of your mail. So -- to protect yourself from that you might want start your .procmailrc with the following simple recipe:

        :0 c
Which (if it is the *first* recipe) simply appends a copy of every incoming message to a file (in your ~/Mail directory by default) named fallback. You can compare the contents of that folder to your inbox until you're confident that things are working as you expect.

Please read the procmail and procmailex (examples) man pages for more details. The author Stephen van der Berg, has also written an automated mail list management package called SmartList -- which is highly regarded among people who've tried it. I like SmartList *much* more than majordomo.


 Dealing with e-mail on a pop3 server

Date: Tue, 28 Jan 1997 04:02:06 -0800 (PST)

From Moe Green:

Is there any way (or any program out there) which will not only get my email from a pop3 server off of one account, then distribute it to multiple users on my system by either the from: or subject: lines???

Example: Perhaps popclient could get the mail and save to temp, then is there a program which would go through and say, hmmm...this mail is from and it goes to root...then the next message is from and it goes to dave???

Thanks for your time, keep up the good work.
-Moe Green,

 It is possible to write procmail scripts that can do this sort of thing. However I don't recommend this approach at all.

The current version of 'popclient' is called 'fetchmail' (because it supports IMAP and some other mail store and forward protocols).

It's default is to fetch the mail from your POP or IMAP server and feed it to the smtpd (sendmail) on your local host. This means that any special processing that would be done by the aliases or .forward files (especially any processing through procmail scripts) will be done automatically.

It is possible to over-ride that feature and feed the messages through a pipe or into a file. It is also possible, using procmail or any scripting language, to parse and dispatch the file. Using anything other than procmail would require that you know *alot* about RFC822 (the standard for internet mail headers) and about e-mail in general.

I did write an article on procmail this month -- but may have submitted it too late for inclusion into this month's Linux Gazette. The gist of it is available on my own mail server (send mail to with a subject of ``procmail'' or ``mailbot'').

The reason I don't recommend all of this is that it violates the intentions and design of internet e-mail. A better solution is to find a provider of UUCP services (or at least SMTP/MX services). UUCP is the *right* way to provide e-mail to disconnected (dial-up) hosts and networks. It was designed and implemented over 25 years ago and all of the mail systems on the Internet know how to gateway to UUCP sites.

As for SMTP/MX services for disconnected hosts/networks. Various ways of hacking sendmail and DNS configurations have been developed in the last few years -- with a variety of shell scripts and custom programs to support them. All of these provide essentially the same services as mail via UUCP over TCP -- but without conforming to any standard (meaning that whatever you learn and configure with one ISP probably won't work with the next one).

Glad I could help. I hope that article on procmail helps.


 Security Problem

Date: Tue, 28 Jan 1997 04:02:06 -0800 (PST)

From Jay:

Recently a cracker got into my linux system on the internet. He didn't do a lot of damage but he did turn off system logging. I guess so I couldn't see what he'd done. Now I can't get it working again....

  1. I've made sure that the syslogd program is running using 'ps'
  2. I've read the syslogd.conf file to make sure it's logging everything, and where it's going to.
  3. I've checked permissions on the log file
  4. I did a 'kill -HUP' on the syslogd process and it writes 'restart' to the log
  5. 'logger' does nothing when I run it (no log entry, no error)
  6. All my C programs that wrote to syslog don't anymore
Anyone have any good ideas what to do from here?


 I do but they are rather too involved for me to type up tonight.

I really recommend that you reinstall the OS and all binaries from scratch whenever you think that root has been compromised on a system. I realize that this is a time-consuming proposition -- but it is the only way to really be sure.

I also recommend tripwire ( in the COAST archive -- and it's mirrors).

Please feel free to write me if you continue to have system security problems.

Sorry to take so long to respond. I've been literally swamped all month.


 More on Security Problem

Date: Tue, 28 Jan 1997 18:56:22 -0800 (PST)

From Jay:

>>> Recently a cracker got into my linux system on the internet.
>> Did you restart the whole system?
>> I would consider replacing syslog from your CD's and
>> restarting your system.
I found that the cracker had replaced my syslogd with a packet sniffer. I think he had copied the syslogd code and replaced parts of it with his sniffer. It seemed to have some functionality but not a lot...

I also found a SUID version of bash in my /tmp directory. My thought is that this is how he originally got root access.

 Not too surprising. He was probably using a 'rootkit.' However he obviously didn't do a very good job of covering his tracks.

You should consider all passwords for all of the systems on the local net to be compromised. Force password changes across the board and consider installing ssh or stelnet (secure, encrypted replacements to rlogin/rsh and telnet respectively).

He probably got in through the "Leshka" sendmail bug (allowing any shell user to create a root owned SUID shell in /tmp/ on any system with an SUID root copy of sendmail (version ~8.6.x to 8.7.x ???) using a bug in sendmail's handling of ARGV[0] and it's subsequent SIGHUP handling.

Everyone using earlier versions of sendmail should upgrade to 8.8.3 or later ( for details).

How important are this system and the other systems on the same LAN segment to your business?

I'd seriously consider hiring a qualified consultant for a full day risk assessment and audit. Unfortunately you'll probably pay at least $125/hr for anyone that's worth talking to and many of the "security consultants" out there are snake oil salesmen.

I personally trust Peter Shipley ( and Brent Chapman ( (co-author of the O'Reilly Firewalls book) Strat Rose ( and Dan Farmer ( (co-author of SATAN). Most of them are live in the SF Bay Area (silicon valley) and most of them aren't available most of the time (Brent is working on a large project to integrate the SGI and Cray WAN's; Strata has accepted a full-time position at, etc).

I only consider myself to be a student, at best an apprentice, at data security. I'm willing to help -- but I can offer a list of satisfied clients for RASA services and I have no official "credentials."


 Dial-up Problem

Date: Tue, 28 Jan 1997 22:56:35 -0800 (PST)

From Seth Vidal:

I was reading your answer in LG(#13) to the individual who had slow rate problems with ppp. Something which he did not mention that might be of help is the MTU. Some isp's set the mtu or have ppp do the negotiation. NOT all. Some of the newer ones have not quite figured out that a 14.4 or 28.8 is not going to get a packet size over 576 very often. If he sets his mtu to 576 (or even 296 for a 14.4) he may be able to force the provider's setting down. I have found that in a standard (slackware or redhat) linux distribution that the mtu defaults to 1500 which will result in slow downs and problems if your modem encounters errors frequently. I know what ppp is "supposed to do" when set up correctly. But he cannot control the ignorance of his ISP and therefore it would be to his behest to give that a try. If you'd like to pass the information along to the individual who wrote the message feel free. I hope this helps him and any others.

Seth Vidal,

 X Window Problem

Date: Tue, 28 Jan 1997 04:02:06 -0800 (PST)

From: Chris Lee,

1.) X Windows I got a Cirrus 5434 1mb video card, whenin 640x480x8bit the video is *fine* not great, I get little specs once in awhile on the screen, they go away with a simple [refresh] but still... When in 800x600x8bit I get lines, not specs anymore, alomst allways horizontial, and about 3pixels high, and allways croos the entire screen, not the virtual screen though, and they also go away with a simple [refresh] thses line occur alot more then the specs did. My vid card works fine in DOS/Windows. Any suggestions ?

 You can look for the SuperProbe utility that comes with most recent distributions. This will provide info that can be autodetected about your video card.

Frankly XWindows configuration under XFree86 is black magic. A few people are really good at it and mere mortals (such as I) just plug along and hope for the best.

The new XFree86 3.1.2 release seems to be better about this but I'm sure that I'm not getting the optimal color and clock settings from my various X installations either.

2.)Is there any Linux or X-Windows mailing-lists ? would help alot for me.

There are many Linux mailing lists -- and some of them and some independent ones cover XFree86 (which is used by Linux, FreeBSD and the rest of the free BSD derivatives (NetBSD and OpenBSD).

The three best web sites for information about Linux seem to be:

I don't know much about X Windows and the XFree86 project but I think they maintain a web site -- probably at

It's an often overlooked fact that there are competitors to Linux in the field of freely available Unix for PC's. You can look at, and for some of those.

Thanks for your time :)
Chris Lee, Computer Science
P.S. You Linux people are great, so much out there, so many people helping you, nothing like this for DOS/Windows

DOS heralded the "sharing" of software (shareware) while Linux and the GNU project has promoted a *giving* of software -- and support.

I think one is largely and extension of the other.

Personally some of the best news I've heard for die hard PC users in the last year is the announcement that Caldera purchased DR-DOS and intends to release the sources as soon as the clean up the code enough to compile cleanly in a sane production environment. Look at for details about that.

OpenDOS will be one of the final pieces in the puzzle of how we (PC users, IS managers, and others) can truly protect the investment we've made in our legacy software. (Currently, with dosemu -- the BIOS emulator, you have to install a copy of DOS unto your system in addition to installing and configuring the Linux interface to your DOS programs -- which is want dosemu provides).

-- Jim

Copyright © 1997, James T. Dennis
Published in Issue 14 of the Linux Gazette


"Linux Gazette...making Linux just a little more lovable!"

CLUELESS at the Prompt: A New Column for New Users

By Mike List,

I'm sure you've heard it before, but Welcome to Linux! You've heard the stories, your friends told you "Don't do it" but the allure of an operating system with at least the power of NT that can run on 4 MB of RAM on the same disk, even on the same partition with your DOS/Windows installation, was too big to be ignored. So you went on a FTP spree or bought a Red Hat or Slackware CD, installed it and you are confused, things don't work the way you expected, the man pages seem to be written in another language, and the people on the USENET keep telling you to RTFM and belittling you.

That's why I decided to ask if I could write this column, it happened to me. Actually, when I got into computers (less than a year ago,) my friend Trippy told me to learn DOS before trying Windows. Thanks Trippy, you saved me a lot of trouble. So when I read about Linux, I thought -WHOA COOL!!, and downloaded the mini-linux distribution from Sunsite."HEY!Wait a minute, how come the keyboard doesn't work right?" Turns out the key table is Portuguese and requires file editing to be usable by us Yanks. Thanks to SGK from the Debian group, I got that squared away, so I decided to go with Debian, but with my small disk and no CD-ROM, Debian's Compatibility/Conflict Resolution was too much for me. So I got a second disk, 100 MB but it was still too small. So I decided to give Slackware a try. That's what I'm running now.

The point is, I'm not a college educated computer expert but I still ended up(for now) with a running linux box. You can too, if you are willing to tinker (hack later, tinker now).I made every possible mistake, I thought until I saw some of the questions in the news groups.

But enough about me, what do you think about me?;-)

The first things you need to know after you install Linux are the most common commands. Here I'm going to assume that you have at least some DOS background. The following list will attempt to correlate Linux commands:

Linux DOS
ls /directory/name cd\directory\name -- dir
ls /directory | more
ls " " | less
dir | more
cat /file type \file
cat " " | more
less /file
" " | more
cp /file /file /to copy \file \to
cd /directory cd\directory
mkdir /directory mkdir \directory
rm /file del \file
This list is not nearly complete, there are many more commands in both OS but these are very likely the most commonly used ones. For command help in DOS type: help :in linux type: man (command, substitute the command name): Both of these help utilities give options or switches that change the nature of the command. You can see that there are similarities in the command line operation of both OS, historically they share a common ancestry. In fact, to use a oversimplified view, at the command line linux could be thought of as SUPERDOS. In fact this SUPERDOS can actually be used to run MS Windows - check into WINE and WABI home pages on the Internet.(More on those later, maybe.)

One of the next things you will need to do is find out how to write or change file contents with an editor.I used to think elvis was the easiest editor, until Konrad Rokicki told me about pico, which comes with the pine mail server. If you used MS Write or Notepad, you'll find it very easy to use. Save Emacs for another day unless you are a good typist, I found the keyboard commands to be confusing for my two-fingered style. If you don't have pico installed, try elvis in the input mode, by typing: input filename, it's pretty easy too, except watch out for command mode and input mode (type: man elvis :and read the page.If you have a CD version of Linux, you either have pico installed or can have it if you choose.

If you're like me one of your priority projects will be to to do is use an Internet protocol to connect to your Internet Service Provider. My ISP uses PPP so that's what I used, and the following descriptions are for PPP.

The first thing you will need to confirm is that your kernel supports PPP, either in the kernel or by loadable modules. Type: pppd :and hit enter. If your kernel doesn't support PPP, you'll get a negative message, if you get a prompt you can assume for now that it's supported.

Next you will need to type: ls /usr/sbin | more :and hit enter. Look for files called ppp-on and ppp-off. Next, type: ls /etc | more : and hit enter. Here you will be looking for a file called resolv.conf. Then type: ls /etc/ppp : you can skip the: | more :this time, since it's a small directory,and hit enter. You'll be looking for files called options and ppp-on-dialer.

Edit your /etc/resolv.conf to look something like:

Naturally you will have to change the name and numeric to match that of your ISP .

Next, edit your /etc/ppp/options file to look something like this:

38400       # at this line you could substitute 19200, 57600, 115200

These two files are necessary to either of the methods I am going to describe.

Now you can use minicom to dial up your ISP. Type: minicom :, and when it loads, type: ATDTYOURISPNUMBER :hit enter. When the remote modem answers you will be prompted for your username and password. When you have responded with this information, a string of garbage characters will run across the screen. Type: ctrl(key)a :then: Q :which will let you out of minicom without hanging up the modem. Then immediately type: pppd :then hit enter. Type: ping YOURISP'SNUMERIC :you will get a message that will inform you if you are connected. If you get a message that says in part "network not reached" try again. If no luck after a couple more tries, check to see that the files you edited have the correct information. Try changing your connection speed in /etc/ppp/options to 19200 and try again. If you connect this time, then one at a time try the faster speeds until you can't connect, then drop back to the fastest speed that worked.

There is an easier method using the script /usr/sbin/ppp-on, that involves editing that file to give your ISPdialup number, username, and password and optionally your connection speed. It is commented to help you figure out how to change those lines that you need to change. When that is done correctly, you can dial up by typing: ppp-on : Pretty cool, huh? If these methods don't work for you, start by reading the PPP_HOWTO in your /usr/doc/faq/howto directory, then respond by e-mail to, telling me any error messages, and I'll try to square you away.

There is another method using the chat program, but I haven't had much luck there, yet. Future installments, if any will fill you in on that if it seems that it's wanted. Personally, ppp-on is just fine for me so far.

you will want to get an e-mail program and a browser, if you don't already. I recommend lynx. It's fast and you don't need X installed to use it. There probably is a lynx binary in your distribution, but if not you can get one from sunsite or other ftp.Pine is a good mail program, and it includes the pico editor, as noted above.

NOTE TO LINUX EXPERTS- I would be glad to accept reasonable criticism of this article and the information therein. I don't really want to put up with heavy fire, if you can help the new user better than me, write an article yourself, there are plenty of avenues where such information would be of great service.

Next Time- e-mail me and ask, otherwise I'll just write about what gave me trouble and how I got past it.

TTYL, Mike List

Copyright © 1997, Mike List
Published in Issue 14 of the Linux Gazette


"Linux Gazette...making Linux just a little more lovable!"

The Cracraft and Lijewski DIRED Programs

By Grant B. Gustafson

The directory navigator and program launcher called "DIRED" in the original incarnations of EMACS has two stand-alone Unix clones. Mike Lijewski's "dired" 2.2 is written in C++ (1996). The original "dired" was written in C by Stuart Cracraft (1980), available as version 3.05 (1997).

Historically, shortly after emacs "dired" appeared in the TECO implementation, a stand-alone version was written by Stuart Cracraft (1980). The emacs version and the C version have not kept up with one another.

Lijewski wrote "dired" in 1990, while at Cornell University Theory Center, without any knowledge of Cracraft's "dired". The Theory Center ran on IBM VM/CMS, under which there is a utility call "file manager". This program manages the flat VM/CMS file system and represents the main user interface into files. The creation of "dired" eased the transition from VM/CMS to Unix.

Lijewski's "dired" has the advantage of hindsight and C++ program development so it promises to be written in modern syntax and very maintainable. Cracraft's "dired" was rewritten in 1996 in ANSI C. It suffers with flaws in both design and readability, but the features are there.

Common features of Cracraft's and Lijewski's "dired"

Minor differences exist in the implementation of these features. Cracraft's dired supports split screen. Lijewski's dired supports scrolling by half-page. Deletes in Cracraft's dired are done in batch whereas Lijewski's dired does them immediately.

Curiously, the common features of the two direds also account for the most often used dired commands.

The differences between Lijewski's "dired" and Cracraft's "dired" in 1997 appear below. Many features commonly exist in both versions, so only the superficial differences are discussed. Strengths and weaknesses of each are also listed.

Unique features of Lijewski's "dired"

Strengths: Weaknesses:

Unique features of Cracraft's Dired 3.05

Strengths: Weaknesses:

Misfeatures of both versions of "dired"

The program tends to be used for browsing and deleting files; users find the other features too obtuse for daily use. Too many commands. Its hard to remember what key does which command.

How to Get Dired

Find at Or email to for location of recent version.

Find Lijewski's c++ dired by sending email to for location of the recent version. If you want to see it on sunsite, then let Mike hear about it!

Copyright © 1997, Grant B. Gustafson
Published in Issue 14 of the Linux Gazette


"Linux Gazette...making Linux just a little more lovable!"

Directory Trees in Outline Format

By James T. Dennis

Since I frequently post messages to various Unix and Linux newsgroups and mailing lists I often get technical questions mailed to me ``out of the blue.''

I recently received a request for a script to produce the following sort of output:


Here was my quick and dirty solution:
        find . | awk -F/ '{for (x=1;x<NF;x++) { printf "\t"}; print $NF}'

... which only does about 80% of the job. The only problem is that the directory entries don't end with the ``/'' to indicate their file type. It was late -- so that's what I sent him.

Here's how that works:

find . just prints a list of full paths (using GNU find). Some non-Linux users may have to using 'find . -print' to accomplish this (or update to the GNU version on their systems).

awk is a text processing language/utility.

The -F (capital ``f'') sets a field separator to the '/' (slash character). Awk defaults to parsing it's input into records (lines) of fields (whitespace delimited). Using the -F allows me to tell awk to treat each record (still just lines) as a group of fields that are separated by slashes -- allowing me to deal with each directory element as a separate element very easily.

The next parameter to awk is a short program -- a for loop (like the C for() construct). It iterates from 1 to NF.

NF in awk is the ``number of fields'' for each record. This, among many other values, is preset by awk as it parses its input.

Awk defaults to reading it's input from a pipe or from each file listed after it's script on the command line. We're supplying it with input through the pipe, of course.

In the body of my awk 'for' loop I simply print a tab for each directory named in that line. This has the appearance of "wiping out" all of the leading directory names and indenting my line as desired.

Finally, after the end of the for loop I simply print the last field ($NF). Note how the printf takes a string similar to C's printf -- and it doesn't assume a newline. I could put C-like format specifiers like %s and %f in there -- and I'd have to supply additional parameters to the printf call if I did.

By contrast the awk print command (no trailing ``f'') does add an ORS (output record separator) character to the end of its line and doesn't treat its first argument as a format specification.

This evening I happened to be cleaning up my home directory (while procrastinating on doing paying work and cleaning the house) I happened across a copy of this and decided to fix it.

                find . | { while read i ; 
                           [ -d $i ] \
                           && echo $i/  \
                           || echo $i 
                           done } \
                           | awk -F/ '
                                /\/$/ { for (x = 1; x < NF -1 ;x++) {  
                                                printf "\t" }; 
                                        print $(NF-1) "/";
                                { for (x = 1; x < NF; x++) {  
                                        printf "\t" } 
                                  print $NF }' 
Note that the original script: 'find ....| awk -F/ ...' is mostly still there. But the script has gone from one line to eleven -- all to get that silly little slash character on the end of each directory name.

(If anyone as a shorter program -- I'd like to see it -- there's probably a fairly quick way to do this using perl and find2perl)

The main thing I've added is the while loop which works like this:

find's output is piped into a group of commands (that's what the braces are for). That group of commands starts with a bash "while... do" loop. The bash "" loop works like this:

                                some command returns no error
                                some commands
'done' Note that, unlike C or Pascal programming the ``condition'' for the while loop is actually any command (or group of commands -- enclosed in braces or parentheses). The fact that programs return values (called errorlevels in DOS and some Mainframe OS) makes all commands implicitly ``conditions.'' (Actually C allows a variety of function calls within conditionals -- but we won't go into that).

Note that some commands might not return values that make any sense -- so those would not be suitable for use with any of the conditional contexts in any shell.

The command I'm using is bash' internal ``read'' command which just takes a variable name as an argument. Note that I don't say ``read $i'' -- the shell would then fill the value of $i into the command (i.e it would ``dereference'' it) and the read command would have no arguments. If you give the read command no argument it simply reads a value and throws it away (no error).

When you set values in bash (or Bourne shell, or zsh etc) you also don't ``dereference'' it. $i=foo would be an error unless you actually wanted to set the value of some variable -- whose name was currently stored in $i to be set to foo.

Back to our script. When the find command stops printing filenames into the pipe, the 'read i' command will fail to get any value -- so the body of the do loop will be skipped.

The 'do' keyword just marks the end of the list of commands in the conditional section and the beginning of the body of the loop (big surprise -- huh?).

The next three lines of the script are another common shell construct --

  1. [ is really an alias for or link to the 'test' command.

  2. -d is a parameter to 'test' that is true if the next parameter ($i) is a directory.

  3. That line ends with a ``\'' (backslash) to mark a continuation character. This causes the shell to treat the next line as an extension of this one.

    I could certainly have put all of this one line. However, for readability I broke it up and formatted it with leading tabs -- otherwise *I* couldn't read it, much less expect anyone else to do so.

    The next line (continuation) starts with the '&&' operator. In bash and related shells you have things like the familiar ``|'' (pipe) and ``;'' semicolon which are called operators. This operator means ``if that last command was O.K. -- returned no error -- then ...''

    You can think of the '&&' operator as do this ``and'' to that (in the *conditional* sense of the the word and).

    The next line uses the '||' operator -- which is, as you might expect, similar to the '&&' operator except it means -- ``if the last command executed returned an error then ...'' This is roughly analogous to the English ``or'' (again, it the conditional sense).

    Of course I could have wrapped this in an 'if ....; then ....; else...' construct -- but I'm used to the '&&' and '||' as are most shell programmers.

    So far all we've done is added a ``/'' character to the end of each directory.

    Now I'm left with a print out of full paths with directories ending in ``/'' (slashes) and other files printed normally -- back to replacing all but the last thing with tabs -- so we pipe the 'while' loop's output into the same awk script we were using before.

    Ooops! Well, almost the same script -- it turns out that awk -F is happy to consider the trailing slash as a blank field on the end of a line. Hmm. O.K. we add an extra condition to the awk script.

    An awk script consists of condition-action pairs. The most common awk ``conditions'' are patterns. That is so say that they are regular expressions (like the things you use grep to search for). A pattern is usually delimited by slashes (a mnemonic to the users of ed, later upgraded ex, later upgraded to vi) although you can also ``match'' against strings that are enclosed in quotes.

    Actions in awk are enclosed in braces.

    Awk is an extremely forgiving language. If you leave out the ``condition'' or ``pattern'' it will execute the action on that line for every record (line) that it comes across. That's what my first script did.

    If you leave off the action (i.e. if you have a line that consists just of a condition) then awk will simply print the record. In other words the default action is {print}.

    When I was a regular in the comp.lang.awk newsgroup (and alt.lang.awk that preceded it) I used to enjoy pointing out that the shorted awk programs in the work are:

    (The first one just prints every line it sees since ``1'' is a ``true'' condition; the second program (a dot) prints every line that has at least one character -- since that is the regular expression for ``any character''. The second program actually does filter out blank lines since awk doesn't count the record separator as part of the line).

    So, the modification of my awk script for this purpose is to add a condition that handles any record that *ends* with a slash. In those cases I convert all *but* the next-to-last field to a tab, and print that ``next-to-last'' field. I also have to add the ``/'' character to the end of that since awk doesn't consider the field separator to be part of any field.

    Finally I add a 'next' command which tells awk not to look for any more pattern-action pairs with *this* record. If I didn't do that than awk would execute the action for each ``directory'' line -- and also execute the other action for it (i.e. it would print a blank line after printing each directory line).

    Is the extra 10 lines of code worth it just to add a slash to the end of the directory names in our outline? Depends on how much your customer is willing to pay -- or how much grief it causes you, your boss or your users.

    Mostly I decided to work on this as a training example. I think there are some neat constructs that every budding shell programmer might benefit from learning.

    The ``find .... | {while read i .... do ... done}'' construct is well worth remember for other cases. It allows you to do complex operations on large numbers of files without resorting to writing a temporary file and having to clean up after it.

    When you write scripts that explicitly create temporary files you suddenly have a host of new concerns -- what do I name it? where do I put it? don't forget to remove it! do I have enough space for it? what if my script gets interrupted? etc.

    To be sure there are answers to each of these. For example I suggest ~/tmp/$0.`date +%Y%m%d`.$$ for a generic temporary filename for any script -- it gives the name of your script, the date in YYYYMMDD format and the process ID of the current instance of your script as the filename. It puts that into the temporary directory under your home (which no one else should have access to). There is virtually no chance of a name collision using this scheme (particularly if you change the date format to +%s which is the total number of seconds since midnight on Jan. 1, 1970). You can use the 'trap' command to ensure that your temp files are cleaned in all but the most extreme cases etc.

    However, as I've said, it's worth understanding how to avoid temporary files -- and usually your scripts will execute faster as a result.

    The [ ... ] && ... || ... construct is absolutely essential to any Unix sysadmin. Many of legacy scripts (particularly those in /etc/rc.d/ -- or it's local equivalent) rely on these operators and the test or '[' command.

    Finally there is 'awk'. I've heard it argued that awk is a dinosaur and that we should convert all the awk code to perl (and presumably most of the Bourne shell and sed code with it). I won't argue that point here. Suffice it to say that anything you learn how to do in awk will just make learning perl that much easier when you get to it. awk is a much simpler language and is phenomenally easy to integrate into shell scripts (as you can see here).

    Jim Dennis, Starshine Technical Services

    Copyright © 1997, James T. Dennis
    Published in Issue 14 of the Linux Gazette

    [ TABLE OF CONTENTS ] [ FRONT PAGE ]  Back  Next

    "Linux Gazette...making Linux just a little more lovable!"

    Welcom to the Graphics Muse
    Set your browser to the width of the line below for best viewing.
    © 1996 by

    Button Bar muse:
    1. v; to become absorbed in thought
    2. n; [ fr. Any of the nine sister goddesses of learning and the arts in Greek Mythology ]: a source of inspiration
    Welcome to the Graphics Muse! Why a "muse"? Well, except for the sisters aspect, the above definitions are pretty much the way I'd describe my own interest in computer graphics: it keeps me deep in thought and it is a daily source of inspiration.

    [Graphics Mews] [Musings] [Resources]
    indent This column is dedicated to the use, creation, distribution, and dissussion of computer graphics tools for Linux systems.
          Last month I had promised to do a review of Keith Rule's new book on 3D File Formats this month. I'll also said there would be a section on adding fonts on Linux in last months colums. Ok, I'm a liar. First, I decided that although Keith's book deserves some examination I felt that another book, Mark Kilgard's OpenGL text, had a more direct bearing on Linux users. I'll consider taking a look at Keith's book some time in the future.
          Second, I had quite a bit of other material for January's column so had decided to move the font discussion to February's column. However, I forgot to update the introduction in January's column to reflect this change. My apologies.
          Now for the bad news: I had a major system crash on the 16th of January which first of all caused me over a week of grief trying to recover and second caused the loss of a large number of files. No, I wasn't doing backups. So shoot me. I managed to recover an earlier copy of this months Muse column from a laptop I have, but I lost a good portion of what I'd already done. Now, as I write this, I have 3 days to get the column done and uploaded. The result is that the book review and a number of other items will have to be put off till another time.
          So, does anyone have a decent tape backup system that can run on ftape drives?
          In this months column I'll be covering, along with how to add fonts to your system:
    • a GIF Animations update: the MultiGIF program
    • some Printer info I gathered in the past month
    • tkPOV V2.0 - a graphical front end to POV-Ray 3.0

    NOTE: I lost all my old email and mail aliases when my system went down. If you have been in touch with me in the past and want to stay in touch ! I'm particularly interested in hearing from Paul Sargent, who was helping me with my look into BMRT. I lost your email address Paul, along with all the messages we'd exchanged on the BMRT article series! Write me (or if you know Paul, please have him contact me)!

    Graphics Mews

          Disclaimer: Before I get too far into this I should note that any of the news items I post in this section are just that - news. Either I happened to run across them via some mailing list I was on, via some Usenet newsgroup, or via email from someone. I'm not necessarily endorsing these products (some of which may be commercial), I'm just letting you know I'd heard about them in the past month.

    xfig 3.2.0 Beta available

          Xfig is a menu-driven tool that allows the user to draw and manipulate objects interactively in an X window. The resulting pictures can be saved, printed on postscript printers or converted to a variety of other formats (e.g. to allow inclusion in LaTeX documents).
          xfig is available on in /contrib/applications/drawing_tools/xfig. You also need a JPEG library, which can be found in /contrib/libraries. and TransFig version 3.2.0-beta1. TransFig contains the postprocessor needed by xfig to convert fig files to one of several output formats, such as PostScript, pic, LaTeX etc. The TransFig package is in the directory /contrib/applications/drawing_tools/transfig.
    indent indent

    Alexander Zimmermann has uploaded another update to his ImageMagick package.

          ImageMagick (TM), version 3.7.9, is a package for display and interactive manipulation of images for the X Window System. The package has been uploaded to as:
    • ImageMagick-3.7.9-elf.lsm
    • ImageMagick-3.7.9-elf.tgz

          ImageMagick supports also the Drag-and-Drop protocol form the OffiX package and many of the more popular image formats including JPEG, MPEG, PNG, TIFF, Photo CD, etc.
          You will also need the package libIMPlugIn-1.0-elf to get it working. These can be retrieved from

    World Movers, the first VRML 2.0 Developer Conference

          I received the following information via email (unsolicited, but its probably the first time I got something I found really interesting via a blind email post). Note that I have nothing to do with this conference, other than I wish they'd invite me to go - expenses paid, of course:

          World Movers, the first VRML 2.0 Developer Conference, will be held on January 30 and 31 at the ANA Hotel in San Francisco, CA.       At World Movers you will:      

    • Select from sessions in three key tracks over two days
      • Content Creation
      • Business Applications of VRML
      • Future Directions and Current Technologies
    • Learn how to create great VRML 2.0 content and applications
    • See and learn about real applications that use VRML
    • Find out about the latest tools for VRML 2.0

    With a pan-industry advisory board and a wide array of hosts and participants, World Movers will give you a complete picture of VRML 2.0 content and applications from all perspectives.

    Register by calling (800)488-2883 or (415)578-6900, or go online at


    PNG Magick Plug-in 0.8

          There is a new plug-in for Unix/Linux versions of Netscape called PNG Magick Plug-in 0.8. This plug-in supports the following file formats: PNG, XPM, TIFF, MIFF, TGA, BMP, PBM, PGM, PPM, PNM, PCX, FITS, XWD, GIF, JPEG, WAV and MPEG-1. It is reported to support Drag and Drop capabilities as well.
          For MPEG-1 support you need the Xew library which doesn't seem to work well with the Linux version of this plug-in.
          PNG Magick Plug-in 0.8 is published under the GNU General public License and is available at
    indent indent

    TkFont v1.1

          There is a new tool for viewing fonts on Linux. I haven't tried this yet so I don't know how well it works. It has been uploaded to in the /incoming directory. The file-name is `tkfont-1.1.tar.gz'.

    Version 0.1.8 of Lib3d is now available from Sunsite.

          Lib3d is a high performance 3d C++ library distributed under the GNU LGPL. Lib3d implements sub-affine texture mapping, Gouraud shading and Z-buffer rasterization, with support for X11, DGA, SvgaLib and DOS.
          Lib3d is available from
          For more information:

    CFP: ACM SIGGRAPH 97 Sketches Program

    Deadline: April 16, 1997
          The following was posted in a number of places. I got it via a friend on the Gimp User mailing list. I have no association with SIGGRAPH (unfortunately) so can offer no other details than the following:

          SKETCHES are live, 15 minute presentations that provide a forum for unique, interesting ideas and techniques in computer graphics. Sketches allow the presentation of late-breaking results, works in progress, art, design, and innovative uses and applications of graphics techniques and technology. Sketch abstracts will be published in the Visual Proceedings.
          Sketches are a fun, educational, high-profile way to show your work and creations. We are seeking submissions in four areas:

    • Animations
    • Applications
    • Art and Design
    • Technical
          For more information, see the SIGGRAPH 97 Call for Participation, send email to , or for the latest, most comprehensive information on how to submit to Sketches and other SIGGRAPH 97 programs, including supplemental documents, please go to:

    To request a copy of the Call for Participation, contact:
      SIGGRAPH 97 Conference Management
      Smith, Bucklin & Associates, Inc.
      401 North Michigan Avenue
      Chicago, Illinois 60611 USA
      +1.312.321.6876 fax

          16 April 1997
          5 pm Eastern Daylight Time
          Final Sketch proposals

    To discuss your concepts and ideas for Sketches, contact:
      David S. Ebert
      SIGGRAPH 97 Sketches Chair
      University of Maryland Baltimore County
      CSEE Department ECS-210
      1000 Hilltop Circle
      Baltimore, Maryland 21250 USA
      +1.410.455.3969 fax

    Did You Know?

          The VRML 2.0 Specification, Moving Worlds from SGI, provides for "spatial audio"? This is a definition of how sound is played in relationship to your point in space and distance from an object which has a sound attached to it. The O2 system from SGI has a VRML browser which was demonstrated on Part 2 of PC-TV's series on Unix which covered commercial Unix options. Part 3 of this series started airing at the end of January and is devoted to our favorite OS - Linux!

          There is a wonderful description on using color palettes with Web pages at The page is a reprinted article by Lisa Lopuck from Adobe Magazine and is quite detailed. Check it out!

          Have you been thinking about using POV-Ray 3.0's new caustics feature? Are you unsure exactly what it does? Want to learn all about it? Then check out The Caustic Tutorial for POV. This is a very detailed explanation on what caustics are and how to use them. Briefly,

    caustics are formed when light is either focused or dispersed due to passing through media with different indices of refraction. Bright spots in the shadows are where light is focused and dark spots are where the light has been dispersed.
    Thanks to for this description (taken from the IRTC-L mailing list).

    Q and A

    Q: What is displacement mapping?

    A: Displacement mapping is not only the perturbing of the surface normal of an object, like a bump maps do, but in fact a distorting of the object itself. You can think of it as a height field over an arbitrary surface. The latest version of BMRT is reported to support displacement maps. Few other publicly available renderers provide this feature.

    Q: I have just downloaded the complete batch of plug-ins from the "Plug-in Registry", and noticed that the "interpolate", "lightest" and "darkest" plug-ins appear to do the same thing as the "blend", "add" and "multiply" channel ops respectively. Is this correct, or is there some difference under certain circumstances?

    A: Not exactly. Blend uses integer values and restricts you to interpolation. Interpolate/Extrapolate uses floating point values and does not restrict the range of the blending value --- you can do extrapolation, too (look at my home page for some examples):

    Lightest and Darkest pick the lightest and darkest pixels from two images. It is not the same as add and multiply except for bilevel images.

    Both of these questions were answered by Mena Quintero Federico, aka Quartic, on the Gimp User mailing list.



    GIF animations update: MultiGIF

          After my first column (Linux Gazette, issue 12), Greg Roelofs wrote me to tell me about another tool for creating animated GIF images. Andy Wardley's MultiGIF allows the use of sprite images as part of the animation. Sprite images are like small sections of an image. Instead of creating a series of GIF images that are all the same size and simply appending each one at the end of the other (as WhirlGIF does) the user can create an initial image along with a series of smaller images that are positioned at offsets from the upper left corner of the full image.
          By using sprites (I'm not completely sure what a sprite really is, but Greg used this term and it appears similar to other uses I've seen - someone correct me if its not the correct use of the term) the GIF animator can reduce the file size anywhere from a factor of two to a factor of 20 in size. As proof, Greg offered his animated PNG-balls, which went from 577k to 233k in size. Another animation, a small horizontally oscillating "Cylon eyes" (referring to the old Battlestar Gallatica metal menace), provided a savings of a factor of 20.
          MultiGIF comes with C source code and is shareware. Andy only asks that you provide a donation if you find you are using it frequently. There is also a utility called gifinfo which can be used to identify GIF files, including multiframe GIF animations.
          Both WhirlGIF and MultiGIF come with fairly decent documentation describing how to use the various command line options. About the only thing that might be missing is why you would use one option over or in conjunction with another, but thats a minor point. I find the use of sprites with MultiGIF and its smaller output files more useful to me. However, new users who are not quite familiar with how to create sprites (including transparency) with tools like the Gimp might prefer the simpler WhirlGIF.

    Adding Fonts to your system

          Fonts are used extensively for creating graphics images. Many of the graphics on my Web pages and in the Graphics Muse use fonts I've installed from collections of fonts on commercial CDs. Fonts are also used for ordinary text in X applications, from the fonts in your xterm to the title bars provided by your window manager to the pages displayed by xman. The difference is hard to distinguish, but whether used for ordinary text or to create outrageous graphics, adding fonts to your system and letting your X server know about them is the first step .
          Just so you know: nearly all X applications accept the "-fn" and/or "-font" command line arguments. This is a feature built into the X Windows API. How this is used depends on the application. For xterms, just use "-fn " to specify the font used in the xterm window. This does not specify what font to use for the xterm title bar. That is controlled by the window managers X resources.
          To know what fonts are available on your system you can look under the font directories for fonts.alias files. There is supposed to be one of these in each directory under /usr/X11R6/lib/X11/fonts, but whether there is or not depends on the distribution you're using. The name to use is the name on the left. For example, under /usr/X11R6/lib/X11/fonts/misc, in the file fonts.alias there is the following line:
    5x7 -misc-fixed-medium-r-normal-
    To use this font with xterms I would do:
           xterm -fn 5x7
    You can actually use the string on the right, but unless you understand how fonts are defined you probably don't want to do this.
          I don't want this to turn into an X Windows column. There are other places for such discussions, and I'm sure LG could use a regular columnist for X. But this column is about computer graphics so this is all I'm going to say about using fonts in X applications from the X resources standpoint. In any case, since the X server is being used to handle the fonts, adding fonts to your system is the same whether you use them for graphics or as X resources.
          Suppose you had a font called westerngoofy that you wanted to use in the Gimp as the start of some neat title graphic for a Web page. By default there isn't an entry in any of the fonts.alias files for westerngoofy, so when you use the text tool in the Gimp it won't show up in the list of available fonts. There are 3 steps to making this font available for use with the Gimp:
    • Grab the fonts and place them in a local directory
    • Configure that directory for use as a font directory
    • Tell the X server about this new font directory
          The first part is simple - grab a copy of the font file and put it in some directory. Make sure you've uncompressed it if the archive you retrieved the file from compresses the fonts. Most X servers don't understand compressed fonts (some do, but all understand uncompressed fonts). The directory can be owned by anyone. It does not have to be a directory under the system fonts directories (generally these are under /usr/X11R6/lib/X11/fonts). On my system I have a "src/X11"

    -Top of next column-
    indent indent indent
    directory under my home directory. Under this I created a "fonts" directory where I put new fonts that I find. If you are the owner of your system and have root access you might want to put the fonts under /usr/local/fonts or someplace similar.
          Note that since TrueType fonts are not supported by default by most X servers we won't concern ourselves with how to use them here. The font format you should be using are Type1 fonts. There are plenty of places to get these, including numerous CD-ROMs available from any decent computer software stores. Some online resources are listed in the Linux Graphics mini-Howto under the "Other Topics" section.
          Next you need to configure your new fonts directory so that the X server can provide you FontName-to-File mappings. To do this you need to get hold of a little Perl script called type1inst, which is short for "Type 1 Install". This script is easy to use and comes with documentation explaining what you about to do. Basically, you run the script to create a couple of files, fonts.alias and fonts.dir, which the X server uses to associate a fonts name to the font file. You can also use mkfontdir, but I like type1inst better. mkfontdir doesn't always seem to be available on all platforms and finding a binary version (or even source) has never been easy for me (I think its buried in the X11 source tree, which I really don't want to download just for one program).
          The last step is to let the X server know about the new font directory. The xset command allows a user to configure a number of options for the X server. One of these options is the paths to search for font files. The format of the command is as follows:

            xset fp+ <path>

    The fp option is used to modify the font path. The plus sign is used to add a font path. Because the plus sign is after the fp the font path specified will be appended to the current list of paths, if any. Using +fp would prepend the new path to the front of the current list. There are other possibilities. Running

            xset -?

    will provide a thorough list of options. The man page for xset also contains good descriptions of the options.
          Now that the server knows where to look, it has to be told to go ahead and check for fonts in the new directories. The rehash option to xset does this. Simply run

            xset fp rehash

    and your new fonts are ready for use!
          Of course, once you've installed the fonts in a directory and run type1inst you can put the xset commands in your .xinitrc file so they are run every time you start up your X environment (such as with the startx script). This is what I do so that I always have access to the set of fonts I've installed from CD-ROMs or from font archives from the net.
          Thats all there is to it. You should now be able to use your fonts with tools like the Gimp or XPaint in order to create lots of interesting logos for Web pages. Enjoy!


    The following links are just starting points for finding more information about computer graphics and multimedia in general for Linux systems. If you have some application specific information for me, I'll add them to my other pages or you can contact the maintainer of some other web site. I'll consider adding other general references here, but application or site specific information needs to go into one of the following general references and not listed here.

    Linux Graphics mini-Howto
    Unix Graphics Utilities
    Linux Multimedia Page

    Some of the Mailing Lists and Newsgroups I keep an eye on and where I get alot of the information in this column:

    The Gimp User and Gimp Developer Mailing Lists.
    The IRTC-L discussion list (I'll get an address next month).

    Future Directions

    Next month:

    Copyright © 1997, Michael J. Hammel
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Linus Torvalds to Receive Annual UniForum Award

    By Richard Shippee,

    Fri, 31 Jan 1997
    Linus Torvalds, considered the "Father of the LINUX Operating System", has been selected by the UniForum Board of Directors to receive The UniForum Award. The Award will be presented to Torvalds on Thursday, March 13th, as part of the morning Keynote Session at UniForum '97, being held at the Moscone Convention Center in San Francisco.

    The UniForum Award, presented annually since 1983, goes to individuals or groups whose work has significantly advanced the cause of open systems over time, or has had an immediate and positive impact on the industry with long term ramifications. The UniForum Board of Directors considered a number of nominees for this year's awards, and voted unanimously in their selection of Linus Torvalds for his breakthrough work on the LINUX kernel and for his pioneering efforts in making his work available at little or no cost to anyone wishing to develop on it.

    Linus Torvalds is the creator and chief architect of the Linux operating system. At the University of Helsinki in the spring of 1991, frustrated with the price of Unix operating systems, Torvalds began writing some software code to handle certain computing chores on the 386. "I noticed that this was starting to be an operating system," he says. Since then, he has traveled all over the world promoting Linux. Although developing Linux has been almost a full-time job for him, he recently accepted a job at Transmeta in Santa Clara, California. He and Tovi Monni recently celebrated the birth of their baby daughter, Patricia Miranda Torvalds.

    The UniForum Board also selected a second Award winner this year: James Gosling of JavaSoft, and his development team, for their work on Java. Gosling will receive his Award at the Wednesday, March 12th Keynote session at UniForum '97.

    The Award presentation to Linus Torvalds, at the Thursday Keynote session, is open to all free of charge but requires attendees to register for UniForum '97. Registrants may also visit the exhibits floor which features booths from a number of LINUX vendors including Comtrol, LINUX International; SSC, publishers of Linux Journal; Red Hat Software and Work Group Solutions. To view the entire UniForum '97 Conference and Trade Show brochure, and to register on-line, please go to

    For additional information contact:
    Richard Shippee, Director of Communications, UniForum 408-986-8840, ext 17,

    Copyright © 1997, Richard Shippee
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Linux Security 101

    By Marsala,

    You can jump down to the section on tcpd
    Or take a peek at the other stuff you need to keep an eye on.

    Ok. You've got Linux beat. You finally got AfterStep set up the way you want it, you've managed to set up ip masquerading for your home LAN, you've managed to set up a cool issue for people to see when they log in, you managed to convert a couple over to the One True OS, and chicks really dig you because, as we all know, Linux geeks are sexy.

    One night as you're peeking at /var/adm/messages, you notice that someone from some place you've never heard of before tried to make 5 ftp connections, 6 telnets, and even an nntp connection. What's up with that?

    Well, Linux (and all Unix type OS's in general) were designed to be a programmer's paradise. The same qualities that makes Linux such a wonderful networking and hacking operating system also expose a few security holes. There are a few programs that you probably rely on or use daily that can be used to gain root access (which is a Bad Thing). What's worse, the commercial distributions that many Linux users depend on have these programs with security holes inside packages that are installed as part of the base system.

    That's the bad news. The good news is that we can make it tougher for the Bad Guys to do their dirty deeds. By checking the Linux ALERTS page, you can find out what the holes we know about are, and how to temporarily plug them up or even fix them up for good. There is also a nice little tool that is probably on your system that we can use to keep them from even having access to our machine.

    And that's what I'm going to focus on. My belief here is that if we can keep the Remote Bad Guys (people who don't have legitimate access to our machines) out, then we only have to worry about the Local Bad Guys (if any). Plus it gives us a chance to fix anything on our machine that is a security hole the RBG's can use.


    There's a daemon that's probably been installed on your machine that you don't know about. Or at least, you're not aware of what it can do. It's called tcpd, and it's how we shut off access to some of the basic services that the Bad Guys can use to get on our system.

    Since tcpd can be pretty complex, I'm not going to go into all the details and tell you how to do the fancy stuff. The goal here is to keep the mischievous gibbons from knocking down what it took so long for use to set up.

    tcpd is called into action from another daemon, inetd, whenever someone tries to access a service like in.telnetd, wu.ftpd, in.fingerd, in.rshd, etc. tcpd's job is to look at two files and determine if the person who is trying to access the service has permission or not.

    The files are /etc/hosts.allow and /etc/hosts.deny. Here's how it all works:

    1. Someone tries to use a service that tcpd is monitoring.
    2. tcpd wakes up, and makes a note of the attempt to the syslog.
    3. tcpd then looks hosts.allow
      • if it finds a match, tcpd goes back to sleep and lets the user access the service.
    4. tcpd now takes a look at hosts.deny
      • if it finds a match, tcpd closes the user's connection
    5. If it can't find a match in either file, or if both files are empty, tcpd shrugs, guesses it's OK to let the user on, and goes back to sleep.

    Now, there are a couple of things to note here. First, if you haven't edited hosts.allow or hosts.deny since you installed Linux, then tcpd assumes that you want to let everyone have access to your machine. The second thing to note is that if tcpd finds a match in hosts.allow, it stops looking. In other words, we can put an entry in hosts.deny and deny access to all services from all machines, and then list ``friendly'' machines in the hosts.allow file.

    Let's take a look at the man page. You'll find the info you need by typing man 5 hosts_access (don't forget the 5 and the underscore).

           daemon_list : client_list
           daemon_list is a list of one or more daemon process  names
             or wildcards
           client_list  is  a  list  of  one or more host names, host
             addresses, patterns or wildcards  that will  be matched
             against the remote host name or address. 
           List elements should be separated by blanks and/or commas.

    Now, if you go take a look at the man page, you'll notice that I didn't show you everything that was in there. The reason for that is because the extra option (the shell_command) can be used to do some neat stuff, but *most Linux distributions have not enabled the use of this option in their tcpd binaries*. We'll save how to do this for an article on tcpd itself.

    If you absolutely have to have this option, get the source from here and recompile.

    Back to business. What the above section from the hosts_access man page was trying to say is that the format of hosts.[allow|deny] is made up of a list of services and a list of host name patterns, separated by a ``:''

    You'll find the name of the services you can use by looking in your /etc/inetd.conf...they'll be the ones with /usr/sbin/tcpd set as the server path.

    The rules for determining host patterns are pretty simple, too:

    And finally, there are some wildcards you can use:

    Ok. Enough technical stuff. Let's get to some examples.

    Let's pretend we have a home LAN, and a computer for each member of the family.

    Our home network looks like this:

    Now, since no one in the family is likely to try and ``hack root,'' we can assume they're all friendly. But....we're not so sure about the rest of the people on the Internet. Here's how we go about setting things up so people on have full access to our machine, but no one else does.

    In /etc/hosts.allow:

    # /etc/hosts.allow for

    And in /etc/hosts.deny

    # /etc/hosts.deny for
    ALL : ALL

    Since tcpd looks at hosts.allow first, we can safely deny access to all services for everybody. If tcpd can't match the machine sending the request to ``*'', the connection gets refused.

    Now, let's pretend that Mom has been reading up on how Unix stuff works, and she's started doing some unfriendly stuff on our machine. In order to deny her access to our machine, we simply change the line in hosts.allow to:

    ALL: except

    Now, let's pretend a friend wants to get something off our ftp server. No problem, just edit hosts.allow again:

    # /etc/hosts.allow for
    ALL: except

    Things are looking good. The only problem is that the name server for is sometimes down, and the only way we can identify someone as being on is through their IP address. Not a problem:

    # /etc/hosts.allow for
    ALL: except
    ALL: 192.168.1. except

    And so on....

    I have found that's it's easier to deny everybody access, and list your friends in hosts.allow than it is to allow everybody access, and deny only the people who you know are RBG's. If you are running a private machine, this won't really be a problem, and you can rest easy.

    However, if you're trying to run a public service (like an ftp archive of Tetris games for different OS's) and you can't afford to be this paranoid, then you need shouldn't put anything in hosts.allow, and just put all of the people you don't want touching your machine in hosts.deny

    You might also want to take a look at the next section.

    Other things to keep in mind

    Security holes in software

    Like I said earlier, a lot of the software that comes standard in CD-ROMs have security holes in them which could let local or even remote users execute commands as root on your system. Keep an eye on Linux ALERTS to find out about problems we know about and how to fix them.

    What services you offer

    Check to make sure that the services you have running on your machine are what you really want to offer. For example, most of us don't have a need to run in.nntpd, yet it's got an entry in /etc/inetd.conf. Do you really want everyone on the Internet to have access to in.fingerd? Do you really need to let everyone on the Internet have access to your ftp server?

    Find what you don't need (or don't want to offer to any passing stranger who might happen across your machine) and either shut it down or deny outside access to it.


    Yeah, yeah, yeah. Everyone's heard the speech about passwords, but they are pretty important. Especially if you're not restricting access to your machine. Remember, if they can get to your machine, they can get on your machine. And if they can get on your machine, they can get root access.

    In case you haven't heard the speech, here's the condensed version:

    1. Make the passwords at least 6 characters long.
    2. Mix the case of the passwords.
    3. Use at least one numeral.
    4. Use at least one non-alphanumeric character.
    5. Change the passwords on a regular basis. About once every
      two months should do for the casual user.
    I have found that using "k-rad" or "leet-speak" helps when you need to make up a password. For example, instead of using the password "foobar", try using "f00b4R!".

    Also, get and install shadow passwords. You might have to recompile a few services, but it's worth the extra protection.

    Finally, it is important to note that only the first 8 characters of the password get used under Linux's login. In other words, if you have a password that looks like abcdefghijklmnopqrstuvwxyz, you will only need to enter abcdefhg in order to gain access to the account. This holds true whether you are using shadowed passwords or not.

    [ Thanks to Olav Wölfelschneider for pointing that out. ]

    File Permissions

    Many of the security holes that exist are because the files are "setuid". That means that a non-root user can execute the files as root. Remove this permission from any files that don't need it. Like mount. It really isn't that much of a hassle to keep one of your virtual consoles logged in as root, and flip over to it when you need to get something done.

    Also, if you have stuff sitting somewhere that you don't want anyone else to see, don't give them world rwx permission on the dir.

    Keep an eye on the syslog

    At least once a day, you need to go check the syslog and see what's been happening. You can find it /var/adm/syslog, and I'd also recommend taking a peek at /var/adm/messages. You'll want to look for multiple connections coming from places you don't know in a short period of time. If they look suspicious, then don't hesitate to slap an entry for the domain into /etc/hosts.deny

    Who you trust

    This is just common sense. It's not a wise idea to give out your root password to someone you just met on IRC 5 minutes ago who claims they can get Apache up and running on your system if you just tell them the root password.

    Set up a guest account with limited read, write, execute abilities and let them use that.

    It's also not wise to let people just log in and fiddle around on your machine. Despite common belief, it is possible to create Unix ``viruses,'' and all you really need is the knowledge, the will, and an opportunity. For more information, see the paper on The Plausibility of Unix Virus Attacks

    Final Word

    To be completely honest with you, the only way to be 100% sure your machine can't be compromised is to physically deny access to it. That means get rid of the modem and ethernet card, fill up any hole in the computer's case with cement, and buy a big, mean pit bull to guard it while you are asleep.

    Well, maybe that's going a bit far. But the point is, if they can't get to your machine, they can't do anything to it. If you think your machine has been compromised, disconnect it from the network, look through the syslog, try to find out how it was compromised, fix the problem, set all new passwords for your accounts, and then reconnect it.

    We might not be able to make the machine 100% secure, but we can make it hard for the Bad Guys to do their thing.


    Copyright © 1997, Marsala
    Published in Issue 14 of the Linux Gazette

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    The Mutt Mailer


    Michael Elkins is a programmer who at one time was involved in the development of the venerable mail-client, Elm. He had some ideas which he would have liked to include in Elm but for whatever reasons the other Elm developers weren't receptive. So he struck out on his own, creating a text-mode mailer which incorporates features from a variety of other programs. These include other mailers such as Elm and Pine, as well as John Davis's Slrn newsreader. As an indication of the program's hybrid nature he has named it Mutt. Although the mailer began as an amalgamation of features from other programs, it has begun to assume an identity of its own.

    Mutt has been in beta-testing for several months now and new versions have been released regularly. Lately I've noticed that binary packages have been appearing in the Sunsite incoming directory, which I take as a sign that the program is now deemed ``suitable for a general audience.'' I have found that it compiles cleanly and works dependably.

    Distinguishing Characteristics

    The composition of messages has always been a thorn in the side of developers of mail clients. After all, a usable mailer is the goal, not a text editor. The typical approach has been to include a simple message composition editor (such as Pico in Pine) and allow the option of starting an external editor of the user's choice. This has certain drawbacks. If in the middle of a message you need an editing function not included by the internal editor, it can be distracting and awkward to switch boats in midstream, so to speak.

    This minor dilemma is neatly side stepped by Mutt; there is no internal editor included. All message composition is done with a familiar editor, preferably a text-mode one so that Mutt can be run at the console as well as under X-windows. As an example, I've set Mutt up to use Vile with a message-specific rc-file (sets word-wrap, etc).

    Mutt can be compiled with a feature unusual in text-mode mail clients: it can fetch mail from a POP server, a duty which is more commonly assigned to an external agent such as Popclient. Compile-time support is also available for PGP-encrypted messages, though theoretically this is only available for US citizens.

    A few of Mutt's other features include:

    Mutt can be run from the command line, if you just want to mail a quick message without having to load your mail-spool file. Incidentally, Mutt uses the mailx (single-file) message format, so the transition from Pine or Elm is painless.

    If you've ever used the Jed editor or Slrn the appearance of Mutt will be familiar. Like these programs Mutt is easy on the eyes, and the amount of coloring used is easily controlled. The documentation supplied with Mutt is very complete, but this isn't one of those programs which takes long to learn.

    Obtaining Mutt

    Binary versions of Mutt are available from the Sunsite archive site, currently in pub/Linux/Incoming. I recommend obtaining the source from the Mutt home site, where the latest versions will first appear. Compiling it yourself allows the program to be tailored to your needs; there are several compile-time options.

    The non-export version, which contains PGP/MIME support, is export-controlled; U.S. citizens can read the file README.US-only and follow the directions to access the files. The non-export version has been exported anyway (against the author's wishes), and can be obtained from the following sites:

    Why not give it a try? The source file is small, and compilation and installation just takes a few minutes. I think you'll like it.

    Last modified: Fri Jan 24 18:54:25 CST 1997

    Copyright © 1997, Larry Ayers
    Published in Issue 14 of the Linux Gazette

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    Window-Manager News

    Window-managers seem to be unique to unix-derived operating systems. Rather than assuming all windowing/GUI tasks, the X-server confines itself to the basic grunt-work of facilitating communications between the graphics hardware and the kernel. This is typical unix behavior, in which complex tasks are broken up into sub-tasks performed by separate programs. This is beneficial to the end-user. If something goes wrong in such a system it is easier to place blame and isolate the problem; flexibility and configurability are also much greater than in systems in which the graphic interface duties are intertwined inextricably with basic kernel functions.

    The end result of this is that if you start the X-server ``bare'' (without a window manager) you will see borderless windows on a gray and black stippled background. Few people want this appearance, so over the years a wide variety of window-managing software has been developed. Some are proprietary, but in the free software world there are several active projects, a few of which I'll discuss in this article.


    The F(?) Virtual Window Manager is, for several good reasons, the most commonly used Linux window manager. It was originally an offshoot of an early manager called Twm, but has evolved considerably in recent years.

    Rob Nation, who was also partially responsible for top and rxvt, was the maintainer of the 1.xx versions of Fvwm. This series reached a developmental plateau a few years ago and a new group of developers adopted the program and initiated the 2.xx series. The 1.xx versions are stable and reliable and are still being used by many people, though they aren't actively maintained.

    I won't go into the basic features of Fvwm, as this topic has been well-covered (by John Fisk and others) in past issues of the Gazette. Since those articles appeared there have been many new features and modules added to Fvwm, a few of which I'll describe.

    By the way, don't be put off by the beta status of the 2.xx versions; since about version 2.0.37 the program has been relatively easy to compile and free of any but very minor bugs. Version 2 is asymptotically approaching a major release which will be version 2.1.

    New Features

    I can't help but think that the developers working on Fvwm2 are keeping an eye on the upstart Afterstep window-manager, which is based on Fvwm2 code. The newest Fvwm2 release (as of Jan 24,1997) is 2.0.45; patches have been incorporated which give Fvwm2 some of the nicer decorative features of Afterstep. These include tiled pixmaps for window-borders and title bars, as well as gradient-shading of the title bar from one color to another. Another addition is the ability to use mini-icons for title bar buttons. If you're not interested in such decorative elaborations they can be easily disabled by editing the fvwm.tmpl file before compilation. The new release is worth obtaining even if you don't care about the new visible features, as many bugs have been fixed. The man-page has also been expanded and updated to cover these changes.

    It's now possible to write Fvwm modules in either Perl or Python. Several examples of each are included in the distribution, which is available from this Hawaiian site.


    If you are fond of the appearance of the NExtstep operating system, you'll probably like Afterstep. This is an offshoot of Fvwm2 development which has attracted much attention recently in the Linux community, to the point where it is being included (despite its beta status) in some newer distributions.

    Afterstep pioneered the use of pixmaps and mini-icons in borders and title-bars, as mentioned in the Fvwm2 section above. But the major difference is the Wharf module, a very configurable tool bar which uses larger-than-normal icons (64x64). The supplied icons are very stylish, and can be configured to have gradient-shaded backgrounds. As with the Fvwm2 Buttons module, the Wharf (NExt calls it a ``dock'') can ``swallow'' applications and other modules. Lately modules designed to be swallowed by the Wharf have become available from the Afterstep web-sites. Among these are a PPP dialer, a CD-player, and a mixer. Check out the Afterstep Home Page for the latest news and releases.


    Possibly as a reaction to the growing number of unnecessary features in the other window-managers, has written a minimalist window-manager called Wm2. This small and fast window-manager was inspired by the Plan 9 manager, which is part of the experimental Plan 9 operating system. There are no icons, virtual desktops, or configuration files, in stark contrast to the other managers discussed here, just nicely framed windows and a simple menu which starts an xterm and lists active and hidden windows. The windows are framed in a distinctive manner, with no top title bar. Instead a shaped tab protrudes from the top of the left side of the window with the title displayed vertically.

    Rather than include a screen shot of Wm2 in action, here are links to the Wm2 web page which has links to both a screen shot and the source itself:

    The Wm2 Page (local)

    The Wm2 Page (WWW)

    Wm2 is still relatively new; I have noticed that it stresses the X-server more than would be expected of such a small application, possibly because of its use of the shaped-window X-extension. Screen refreshes seem to be slow. Nonetheless in this third version it seems to be stable, and it provides a refreshing contrast to the complexity of the other window-managers. The only configuration involved comes before compilation of the source. The various colors and preferred terminal emulator can be set in the Config.h file; after installation the only way to change these settings is to re-edit and recompile.

    If you'd like more information on these as well as several other window-managers, visit
    this excellent site, which has many links and screen shots.

    Last modified: Fri Jan 24 19:11:42 CST 1997

    Copyright © 1997, Larry Ayers
    Published in Issue 14 of the Linux Gazette

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    Shells For The End User

    My first shell, though I didn't know it by that name, was in DOS. It couldn't do much more than simply execute commands, but it served my needs at the time. Later on I discovered the commercial DOS replacement 4DOS, by JP Software. This came as something of a revelation to this novice computer user. Suddenly I could do file-name completion, use aliases, and change to a directory on a different drive with simple keystrokes. Wow, I thought, how did those programmers at JP Software think of so many clever command-line functions and options!

    I later learned that 4Dos (and its OS/2 sibling, 4OS/2) were influenced and inspired by the various shells used on unix systems. When I first began using Linux I was able to learn the rudiments of the Bash shell fairly quickly because of past experience with the JP Software products.

    The ``Bourne-Again'' Shell

    New users of Linux are encouraged (in part by distribution defaults) to use the GNU Bash shell. Bash has been polished over the years to the point that any remaining bugs probably affect only the skilled users who make use of its more arcane functions. Bash, and its reduced-function alias sh, work well as agents for executing shell scripts. As a command shell in a console or an xterm Bash provides many labor-saving shortcuts and functions, most of which beginning users don't use. Reading the voluminous Bash documentation I began to realize that using Bash the way most users do, i.e. as the default login and command shell, touches only a small fraction of its capabilities. O'Reilly has published a three-hundred-page book detailing Bash shell programming and usage !

    Recently Chet Ramey, the maintainer of Bash, released version 2.00 to the FTP sites. After reading the list of changes and bug-fixes I concluded that advanced users will be more appreciative of the release than will common end-users, like myself. It's an odd feeling to learn of a feature by finding out that bugs have been fixed in it! The documentation for Bash is extensive; the man pages are available now in HTML format (in a separate file called bash-doc-2.0.tar.gz). Bash can be obtained both from Sunsite and its mirrors (in /pub/gnu) and from the main GNU site.

    I remember the first time I navigated my way through the Slackware installation menus; being offered the option to install tcsh and zsh made me realize how little I knew. What were these alternative shells? Evidently some users preferred them to bash, but why?

    All of the shells discussed in this article are extensively documented, but that very feature, as helpful as it is to advanced users, can make it difficult to get a rough idea of why one shell might be preferable to another. Luckily it isn't hard to install another shell just to try it out. Edit the file /etc/shells (logged in as root) and add a line with the path to the new shell. Then execute the command chsh; a default choice will be offered to you. Ignore it and type in the name (with path) of the new shell. You'll have to log out and log back in to activate the new shell.


    In issue 12 of the Gazette wrote a good introductory article about Tcsh; this article also shows how Jesper's program Dotfile Generator can be used to help write Tcsh resource files without spending many hours reading the manual. Since that article appeared a new version of the Dotfile Generator has been released which includes a module to generate Bash resource files. I highly recommend this program, which is available from this site. The Dotfile Generator won't overwrite your existing files; it writes to another filename (such as .bashrc-dotfile) This file can then be edited; I usually transplant sections to my original files to try things out. The Dotfile Generator allows you to try various features of your shell without having to learn the precise rc-file syntax first. 1

    A little resource-file editing will be necessary to change over to Tcsh. The aliases which you have defined can be transplanted from your ~/.bashrc to ~/.cshrc without alteration, but the environment variables are another matter. Bash (and other ``Bourne-compatible'' shells, such as Zsh) uses a different format for this than Tcsh. As an example, export INFODIR=/mt/info in the ~/.bash_profile would have to be changed to setenv INFODIR /mt/info in ~/.tcshrc. I recommend going to the trouble of transferring aliases and environment variables if you want to give Tcsh a try. If you don't you'll be continually distracted by commands which don't work, and you will tend to blame the shell.

    The one feature which really stands out (if you're accustomed to Bash) is the spelling-correction. When either a filename or command is misspelled the shell pops up a suggested correction. If you tend to type commands quickly and press ``enter'' without rereading what you've typed you'll love this. Sometimes the shell is wrong, though, but pressing n rather than y will force the shell to try and execute what you actually typed.


    After using Tcsh for a while, you may find yourself thinking, ``I really don't want to switch completely to Tcsh; if only Bash had that spelling correction built in!'' Zsh might be what you want.

    Zsh is a Bourne-compatible shell like Bash but with several csh-like features added. It also resembles the proprietary Korn shell as well as Pdksh, a free Korn-shell clone. It's not at all difficult to adapt Bash configuration files so that Zsh can use them as the syntax is nearly identical. ~/.zshenv is analogous to ~/.bash_profile, while ~/.zshrc corresponds to ~/.bashrc.

    The first thing you notice when using Zsh for the first time is the prompt, which by default looks like this:

    <machine-name>#                               /usr/local/src

    As you can see, the current directory is on the right hand side of the screen, giving more room for a command before the line breaks. When a typed command reaches the path on the right the path disappears to make room.

    The spelling correction behavior seems to be identical to that of Tcsh. As with Bash and Tcsh, completion of paths and filenames is bound to the tab key. Zsh has an elaborate implementation of programmable completion, in which file-type specific behavior for completions can be set in the resource-files.

    One helpful aspect of Zsh's completion behavior deserves notice. Often there will be a filename and a subdirectory with the same prefix, say if a file called sample-2.01.tar.gz is unarchived into the directory in which it resides, creating in the process a new subdirectory called sample-2.01. Try the command cd sam<TAB> with some shells and you will be asked if you want to change directory to sample-2.01.tar.gz or to sample-2.01. Zsh is smart enough to realize that directories don't normally have a tar.gz suffix, and changes to the directory without comment or question.

    The Zsh distribution contains extensive help-files which are in the Info format, allowing them to be browsed from within Emacs or with a stand-alone Info reader. After reading these documents I came away with the impression that Zsh probably rivals Bash in the number of arcane features and programming abilities. If you would like to see examples of the complexity possible in Zsh configuration, take a look at The Next Level, a package of Linux configuration files with explanation which has become a part of recent Red Hat distributions. The Next Level's author, Greg J. Badros, has included an elaborate set of Zsh resource files. I found them to be quite informative as an example of what's possible with this shell.

    Zsh seems to be under active development; version 3.00 was released last year, and there have been minor releases since then. There is a Zsh home-page here which can serve as a good introduction.


    These shells certainly aren't hard to find; most distributions I've seen include preconfigured packages for all three of them. One caveat: if you decide to settle on Tcsh or Zsh as your login shell don't remove Bash, or its symlink /bin/sh. Many shell scripts rely on /bin/sh in order to run properly. Some packages, such as the Andrew User Interface System, like to have csh available, so if you have the disk-space Tcsh, along with its symlink /bin/csh may as well be retained even if it's not your login shell.

    The choice of shells reminds me of the eternal debate between vi-users and emacs-users. A decision depends more on working-style and personality than logic; try them all and see which one fits!

    Last modified: Fri Jan 24 23:34:09 CST 1997

    Copyright © 1997, Larry Ayers
    Published in Issue 14 of the Linux Gazette

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    Novice Bash Tip -- Edit command-lines "joe-style"

    By Joel Wilf,

    If like me, you come from the world of DOS and WordStar, you feel right at home with the joe editor, which uses WordStar keystrokes.

    But as soon as you exit joe, you're back in the land of bash, where command-lines are edited "emacs-style." Soon, your fingers are confused. Before you know it, you're pressing <control>-d to move the cursor, only to find your command-line disappearing.

    But why use one set of keys to edit text and another to edit commands? The beauty of Linux is that you can customize it to your heart's content. Here's how to make bash act like our old friend, joe:

    Step 1: define keys with .inputrc:

    The bash command-line is handled by the GNU readline library. So it's not surprising that bash uses the same keystrokes as GNU emacs. Luckily, you can change these key-bindings simply by setting new values in the file .inputrc.

    The first step is to go to your $HOME directory and open or create a text file named .inputrc. Then add the following lines, which tell bash to use the basic joe keystrokes:

    "\C-d": forward-char "\C-s": backward-char "\C-f": forward-word "\C-a": backward-word "\C-g": delete-char "\C-t": kill-word "\C-y": kill-whole-line
    You can also add the following lines, which fix the behavior of the <home>, <end>, <delete>, and <backspace> keys:
    "\e[1~": beginning-of-line "\e[3~": delete-char "\e[4~": end-of-line DEL: backward-delete-char
    Finally, you can use .inputrc to modify any one of the dozens of keystrokes and variables that control bash. (Among other things, you can get bash to stop beeping at you!) Check the READLINE section of the bash man page for details.

    Step 2: fix terminal settings with stty:

    An experienced Linuxer will see that the changes we made to .inputrc has created a problem. We set <control>-s to it's WordStar meaning. But the Linux terminal uses <control>-s to send the "stop" signal. Pressing <control>-s freezes the terminal until you type <control>-q, the "start" signal.

    The easiest way to fix this is to tell the terminal to use a different "stop" key. To reassign "stop" to <control>-p, type the following line (and put it in your .bashrc to make it permanent):

    stty stop '^p'
    You can prove this works by pressing <control>-p then <control>-q. It's also a good idea to check your terminal configuration -- especially if you change other keys with .inputrc. Type:
    stty -a
    This will display your terminal settings. If you reassigned the "stop" key as shown above, you should see "stop = ^P".

    Now you're home free. All you have to do is exit and log in again. And you can edit commands "joe-style."

    Copyright © 1997, Joel Wilf
    Published in Issue 14 of the Linux Gazette

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    Pick an Editor, Any Editor

    By Jens Wessling,

    im (VI iMproved)

    One day I realized that I seem to spend an inordinate amount of time in front of a computer screen and more precisely with a text editor in front of me. This should hardly have been a surprise to me considering I work with computers for eight to ten hours a day and then I go home and spend several more. I guess that this obvious fact finally struck home with me. I would guess I spend about 20-30 hours a week in a text editor alone. With some quick calculations I realized that this adds up to over 1000 hours a year. That is over 40 solid days of my life every year in an editor. (That is a conservative estimate.) This realization spurred me to try to optimize the time I spend in my editor.

    The first step I took was to try and find the best editor around. I started asking around to see who used what and to try to find out what the important qualities of an editor were. Don't make this mistake. Editors are one of the most religious beliefs a programmer holds. Every programmer is convinced that there's is the best. My office-mate uses PICO, some of my co-workers use EMACS, VI, SlickEdit, or any one of an unending list. Every person I talked to insured me that their selection was by far the best. When I inquired about the differences, they were primarily insignificant. That was when I learned the horrible truth. Most editors are essentially equivalent. No matter how hard people insist, most editors have more features than any user will ever use. (Except PICO). In the Linux community, these selections basically fall in to one of two categories. VI clones, or Emacs. My recommendation is that everyone learn one of these well. It doesn't really matter which one, just pick one, stick with it and use it. (Religiously if you must.)

    I have gone to great lengths to learn VIM, a VI clone. And certainly if not THE best, one of the top contenders. Many features are shared among VI clones, basically the VI subset. The additional features are basically individual to each clone. VIM comes with most, if not all, Linux distributions. The home page for VIM is VIM is in active development and is getting better by the day. Syntax highlighting should be out, if not by the time you read this, then soon thereafter.

    I will assume that most people know the basics of VI and want to change it from a simple tool to a powerful one. I will share some of the handy tips and tricks I use.

    Programming, Tabs, and Tags.
    ctags is a marvelous utility for C and C++ Programmers. ctags comes with the VIM distribution. What this utility does is create a list of all the subroutine names in the files you specify and allow you to jump to the given subroutine while in you editor with just one keypress. The way you run ctags is simple.


    ctags *.c or ctags *.cpp

    Then, crank up your editor and move to wherever it is you call any subroutine from and press [CTRL]-]. This will take you immediately to wherever the routine is, even if it is in a different file.

    File Switching
    I frequently work with several files concurrently and I need to switch between these files continually. The command to switch to another file in VIM is ":e fn". The shortcut to switch to the last file edited is ":e #". This is fine for normal use, but I switch files often, and 4 keystrokes seems like a bit much. This is where VIM's key mapping comes in. VIM like most editors has an rc file. It is called .vimrc, what a shock. 8) In this file I have the following command.


    " Save and switch to other buffer. map N :w [CTRL]-M

    This command lets me switch buffers with a single keypress. The other nice feature in VIM for switching between files is tab completion for file names. The way tab completion works is to take whatever letters you have typed in so far on for the file name and find all of the files that could possibly match. Hitting tab will scroll through the list of files until you find the one you want. If no beginning letters are specified for the file name, it will scroll through them all.

    I do a LOT of coding and I find that I often need to comment out blocks of lines. I have developed 2 macros for handling this with a minimum of effort.

    map C 0i/*[CTRL-ESC]A*/[CTRL-ESC]j map T 0xx$xxj

    If you examine the first line, you will see that it does the following.
    The second line does the following. I can type "12C" in command mode and it will comment out the next dozen lines. and "12T" will uncomment a dozen lines that were commented by "C".

    Keep in mind that when you remap keys, they lose there original values. In this case, "C" was an odd Delete until end of line and next several lines into a given buffer, and "T" was a command I can't really figure out from the documentation. I don't really miss these two but be careful that you don't map "i" or "x" or anything else you might need later.

    Have fun with this. I hope to have more later.
    jEnS Wessling

    Copyright © 1997, Jens Wessling
    Published in Issue 14 of the Linux Gazette

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    A Philosophy for Change from DOS to Linux

    By R. Frank Louden

    Unavoidable Confusion

    On the surface, changing from a MS DOS/MS Windows user to a Linux user is not such a major change. After all, to change directories in Linux, you use the ``cd'' command and that is the same as DOS. Linux provides X windows as a GUI and there are a number of similarities with MS Windows.

    So maybe all that is necessary is to learn a few different commands and you are off and running. Well, right and wrong.

    You might find yourself in the situation I was in when I first decided to install Linux. I had never had any experience with Unix or Linux or much of anything else outside of the realm of Microsoft.

    The Intel/Microsoft consortium had given me a false sense of command over my PC. I had no idea of the ``behind the scenes'' activity that went on when DOS booted and Windows came up with it's attractive colors and cute little icons. I began to learn a bit when I tried to setup some software that wasn't MS applications. At work I learned that it was necessary to occasionally contact an equipment manufacturer to get the appropriate drivers for MS Windows. But all-in-all I was successful in almost every attempt. Little did I know...

    Fools Rush IN...

    As you may have deduced, I work with computers and less obvious (but it'll get even less obvious as we go along, I'm sure!) I have some schooling in the computer field. So it won't be too surprising to find that I was beginning to feel somewhat stifled by the MS environment. I knew there were more colors, more sounds, more ways of doing things than I saw on the shelf (at a rather high $$ amount, I might add) in my local computer store and in the pages of my favorite computer magazines.

    One day, a friend mentioned Linux to me. She was quite an Internet fan. She spent hours in IRC channels and had heard about some of the Unix applications from the I-net dinosaurs (Unix users). So one day, while browsing through the computer books shelves at my favorite bookseller's, I noticed a copy of ``Linux Unleashed'' published by Sam's Publishing. I bought it thinking I'd just see what all the fuss was about.

    Time Wounds All Heels

    I couldn't wait. When I opened the pages and began reading I was intrigued. The complexity and yet the continuous assurances that it *could* be done had me all fired up to try out this ``experimental'' OS.

    Lucky me! A CD was glued inside the back cover of the book. My problem was, all I owned was a 386SX with 2 MB of memory and a 65 MB hard-drive. Not enough! So I bought a new PC.

    I ordered a Micron with 16 MB of memory and a 1.6 GB hard drive and a CD-ROM drive. A heck of a lot of machine to my way of thinking! When it arrived, it came pre-loaded with MS Win95 (doesn't everything?)

    I decided to use FIPS to do a ``non-destructive'' repartition of my new hard-drive. Well, it worked but the problem is the FIPS program took every bit of empty space on the drive, I couldn't write a single file in Win95 and I wasn't ready to completely forsake my old OS. So, having already made a backup (yeah, right!) I did a complete reformat of my C drive. I split the drive into 4 logical partitions and saved one of them for Linux exclusively.

    Even for someone with a fair amount of PC experience, there is room for mistakes, doing what I was doing, and I made 'em. One thing I didn't do (I didn't know about this at the time) was to also create a small partition to use as Linux swap space. I did this a couple of months later when I re-installed to upgrade to Slackware 3.1.

    So here is a warning...

    Take your time and learn about that machine and the wondrous things it is capable of doing for you. If later (and probably MUCH later) you find it is boring doing the Microsoft Word cut-and-paste shuffle, and Doom starts putting you to sleep, and you've invested in a class or two in Computer Science at your local community college, Linux might be just the thing.

    A Coincidence?

    While I was typing away on this article, the phone rang. It was my friend Ben and he had just hooked up his brand new P166 last evening. First thing he said was, ``I got this new computer last night and I need help before I throw it out the window.'' I got up and drove over to his place. (Coldest day of the year so far! Brrrrr!) I looked at his machine. Pre-loaded with Win95 (aren't they all?) He didn't know what to do once the system booted and displayed the new GUI. I showed him a couple of things and then told him not to install Linux. He's definitely not ready!

    Who Is Ready?

    None of us who are migrating from MS dominance. It's that simple. But don't let that discourage you. If you know a bit more about PCs than the occasional, at work, or gaming user and if you are as fascinated by computing concepts and advances (Java, SMP, Graphics rendering, etc.) as I am. If you LIKE to program or if you want to set up as an ISP, then Linux is for you. And be prepared, Linux is a whole different animal!

    Time Heals All Wounds

    Learning takes time and in time you will learn. I started with Linux in March of 1996. In the last ten months, I have installed Linux (Slackware at home and Debian at work) about eight times. I have learned something every day. I will say that while Linux is priced right, I have spent more on books in the last ten months than I had in the last 5 years.

    Here are some of the things I have accomplished...

    I have setup...

    I am learning... And there are many, many other places to go.

    Let me say that ``setup'' is not truly the best word to use. In many instances the setups I mentioned above required only that I tweak a configuration file or adjust a Makefile. In some instances the program refused to work and I had to read and study and yes, I had to ask a couple of questions from the newsgroups too.

    Out of the box, my printer didn't function so I had to read the Printing HOWTO. Of course, it might have worked but how would I know since I didn't have any idea about how lpr was used to queue up a print job. Then I needed to get a SLIP or PPP connection functioning so I could ask those questions on the newsgroups. I had been taught some Ada when in school and when I saw GNAT was available, I wanted to have it so I might refresh my skills there. I had to wait for InfoMagic's September ``Linux Developer's Resource'' before I was able to get a GNAT installed that would compile anything.

    Just last week I got Pov-Ray up and running and I have been enthusiastic about ray-traced images since I first saw a ringed planet scene created with it. But I had to wait...and tinker...and wait...and read...and make mistakes...and start all over again. There are times when, like my friend Ben, I feel like throwing the PC out the window and I have learned to move on to something else. And whenever I move on, I learn more.

    Linux Yes!

    So I am sold! I have not as yet taken the MS partitions off of my machine but 95% of the time I am working within the Linux environment. Although sometimes my frustrations run high, I can honestly say that I have not had as much fun with a computer since I first started my Pascal classes back a few years ago.

    So here I am, somewhere between a novice and a guru, lost in the Linux OS Wonderland. I'm having a great time...why don't you join me?

    Copyright © 1997, R. Frank Louden
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Procmail Mini-Tutorial:

    Automated Mail Handling

    by , Proprietor, Starshine Technical Services

    Converted to HTML by

    procmail is the mail processing utility language written by of Germany. This article provides a bit of background for the intermediate Unix user on how to use procmail.

    As a "little" language (to use the academic term) procmail lacks many of the features and constructs of traditional, general-purpose languages. It has no "while" or "for" loops. However it "knows" a lot about Unix mail delivery conventions and file/directory permissions -- and in particular about file locking.

    Although it is possible to write a custom mail filtering script in any programming language using the facilities installed on most Unix systems -- we'll show that procmail is the tool of choice among sysadmins and advanced Unix users.

    Unix mail systems consist of MTA's (mail transport agents like sendmail, smail, qmail mmdf etc), MDA's (delivery agents like sendmail, deliver, and procmail), and MUA's (user agents like elm, pine, /bin/mail, mh, Eudora, and Pegasus).

    On most Unix systems on the Internet sendmail is used as an integrated transport and delivery agent. sendmail and compatible MTA's have the ability to dispatch mail *through* a custom filter or program through either of two mechanisms: aliases and .forwards.

    The aliases mechanism uses a single file (usually /etc/aliases or /usr/lib/aliases) to redirect mail. This file is owned and maintained by the system administrator. Therefore you (as a user) can't modify it.

    The ".forward" mechanism is decentralized. Each user on a system can create a file in their home directory named .forward and consisting of an address, a filename, or a program (filter). Usually the file *must* be owned by the user or root and *must not* be "writeable" by other users (good versions of sendmail check these factors for security reasons).

    It's also possible, with some versions of sendmail, for you to specify multiple addresses, programs, or files, separated with commas. However we'll skip the details of that.

    You could forward your mail through any arbitrary program with a .forward that consisted of a line like:

    "|$HOME/bin/your.program -and some arguments"

    Note the quotes and the "pipe" character. They are required.

    "Your.program" could be a Bourne shell script, an awk or perl script, a compiled C program or any other sort of filter you wanted to write.

    However "your.program" would have to be written to handle a plethora of details about how sendmail would pass the messages (headers and body) to it, how you would return values to sendmail, how you'd handle file locking (in case mail came in while "your.program" was still processing one, etc).

    That's what procmail gives us.

    What I've discussed so far is the general information that applies to all sendmail compatible MTA/MDA's.

    So, to ensure that mail is passed to procmail for processing the first step is to create the .forward file. (This is safe to do before you do any configuration of procmail itself -- assuming that the package's binaries are installed). Here's the canonical example, pasted from the procmail man pages:

    "|IFS=' '&&exec /usr/local/bin/procmail -f-||exit 75 #YOUR_USERNAME"

    This seems awfully complicated compared to my earlier example. That's because my example was flawed for simplicity's sake.

    What this mess means to sendmail (paraphrasing into English) is:

    This complicated line can be just pasted into most .forward files, minimally edited and forgotten.

    If you did this and nothing else your mail would basically be unaffected. procmail would just look for its default recipe file (.procmailrc) and finding none -- it would perform its default action on each messages. In other words it would append new messages into your normal spool file.

    If your ISP uses procmail as its local delivery agent then you can skip the whole part of about using the .forward file -- or you can use it anyway.

    In either event the next step to automating your mail handling is to create a .procmailrc file in your home directory. You could actually call this file anything you wanted -- but then you'd have to slip the name explicitly into the .forward file (right before the "||" operator). Almost everyone just uses the default.

    Now we can get to a specific example. So far all we've talked about it how everything gets routed to procmail -- which mostly involves sendmail and the Bourne shell's syntax. Almost all sendmail's are configured to use /bin/sh (the Bourne shell) to interpret alias and .forward "pipes."

    So, here's a very simple .procmailrc file:


    This just appends an extra copy of all incoming mail to a file named "mail.backup" in your home directory.

    Note that a bunch of environment variables are preset for you. It's been suggested that you should explicity set SHELL=/bin/sh (or the closest derivative to Bourne Shell available on your system). I've never had to worry about that since the shells I use on most systems are already Bourne compatible.

    However, csh and other shell users should take note that all of the procmail recipe examples that I've ever seen use Bourne syntax.

    The :0 line marks the beginning of a "recipe" (procedure, clause, whatever. :0 can be followed be any of a number of "flags." There is a literally dizzying number of ways to combine these flags. The one flag we're using in this example is 'c' for "copy."

    You might ask why the recipe starts with a :0. Historically you used to use :x (where x was a number). This was a hint to procmail that the next x lines were conditions for this recipe. Later, the option was added to precede conditions with a leading asterisk -- so they didn't have to be manually counted. :0 then came to mean something like: "count them yourself."

    The second colon on this line marks the end of the flags and the beginning of the name for a lockfile. Since no name is given procmail will pick one automatically.

    This bit is a little complicated. Mail might arrive in bursts. If a new message arrives while your script is still busy processing the last message -- you'll have multiple sendmail processes. Each will be dealing with one message. This isn't a problem by itself. However -- if the two processes might try to write into one file at the same time they are likely to get jumbled in unpredictable ways (the result will not be a properly formatted mail folder).

    So we hint to procmail that it will need the check for and create a lockfile. In this particular case we don't care what the name of the lock file would be (since we're not going to have *other* programs writing into the backup file). So we leave the last field (after the colon) blank. procmail will then select its own lockfile name.

    If we leave the : off of the recipe header line (ommitting the last field entirely) then no lockfile is used.

    This is appropriate whenever we intend to only read from the files in the recipe -- or in cases where we intend to only write short, single line entries to a file in no particular order (like log file entries).

    The way procmail works is:

    It receives a single message from sendmail (or some sendmail compatible MTA/MDA). There may be several procmail processing running currently since new messages may be coming in faster than they are being processed.

    It opens its recipe file (.procmailrc by default or specified on its command line) and parses each recipe from the first to the last until a message has been "delivered" (or "disposed of" as the case may be).

    Any recipe can be a "disposition" or "delivery" of the message. As soon as a message is "delivered" then procmail closes its files, removes its locks and exits.

    If procmail reaches the end of it's rc file (and thus all of the INCLUDE'd files) without "disposing" of the message -- than the message is appended to your spool file (which looks like a normal delivery to you and all of your "mail user agents" like Eudora, elm, etc).

    This explains why procmail is so forgiving if you have *no* .procmailrc. It simply delivers your message to the spool because it has reached the end of all its recipes (there were none).

    The 'c' flag causes a recipe to work on a "copy" of the message -- meaning that any actions taken by that recipe are not considered to be "dispositions" of the message.

    Without the 'c' flag this recipe would catch all incoming messages, and all your mail would end up in mail.backup. None of it would get into your spool file and none of the other recipes would be parsed.

    The next line in this sample recipe is simply a filename. Like sendmail's aliases and .forward files -- procmail recognizes three sorts of disposition to any message. You can append it to a file, forward it to some other mail address, or filter it through a program.

    Actually there is one special form of "delivery" or "disposition" that procmail handles. If you provide it with a directory name (rather than a filename) it will add the message to that directory as a separate file. The name of that file will be based on several rather complicated factors that you don't have to worry about unless you use the Rand MH system, or some other relatively obscure and "exotic" mail agent.

    A procmail recipe generally consists of three parts -- a start line (:0 with some flags) some conditions (lines starting with a '*' -- asterisk -- character) and one "delivery" line which can be file/directory name or a line starting with a '!' -- bang -- character or a '|' -- pipe character.

    Here's another example:

    * ^From.*

    This is a simple one consisting of no flags, one condition and a simple file delivery. It simply throws away any mail from "someone I don't like." (/dev/null under Unix is a "bit bucket" -- a bottomless well for tossing unwanted output DOS has a similar concept but it's not nearly as handy).

    Here's a more complex one:

    * !^X-Loop:
    | $HOME/bin/my.script

    This consists of a set of negative conditions (notice that the conditions all start with the '!' character). This means: for any mail that didn't come from a "daemon" (some automated process) and didn't come a "mailer" (some other automated process) and which doesn't contain any header line of the form: "X-Loop: myadd..." send it through the script in my bin directory.

    I can put the script directly in the rc file (which is what most procmail users do most of the time). This script might do anything to the mail. In this case -- whatever it does had better be good because procmail way will consider any such mail to be delivered and any recipes after this will only be reached by mail from DAEMONs, MAILERs and any mail with that particular X-Loop: line in the header.

    These two particular FROM_ conditions are actually "special." They are preset by procmail and actually refer to a couple of rather complicated regular expressions that are tailored to match the sorts of things that are found in the headers of most mail from daemons and mailers.

    The X-Loop: line is a normal procmail condition. In the RFC822 document (which defines what e-mail headers should look like on the Internet) any line started with X- is a "custom" header. This means that any mail program that wants to can add pretty much any X- line it wants.

    A common procmail idiom is to add an X-Loop: line to the header of any message that we send out -- and to check for our own X-Loop: line before sending out anything. This is to protect against "mail loops" -- situations where our mail gets forwarded or "bounced" back to us and we endlessly respond to it.

    So, here's a detailed example of how to use procmail to automatically respond to mail from a particular person. We start with the recipe header.


    ... then we add our one condition (that the mail appears to be from the person in question):

    * ^

    FROM is a "magic" value for procmail -- it checks from, resent-by, and similar header lines. You could also use ^From: -- which would only match the header line(s) that start with the string "From:"

    The ^ (hiccup or, more technically "caret") is a "regular expression anchor" (a techie phrase that means "it specifies *where* the pattern must be found in order to match." There is a whole book on regular expression (O'Reilly & Associates). "regexes" permeate many Unix utilities, scripting languages, and other programs. There are slight differences in "regex" syntax for each application. However the man page for 'grep' or 'egrep' is an excellent place to learn more.

    In this case the hiccup means that the pattern must occur at the beginning of a line (which is its usual meaning in grep, ed/sed, awk, and other contexts).

    ... and we add a couple of conditions to avoid looping and to avoid responding to automated systems


    (These are a couple more "magic" values. The man pages show the exact regexes that are assigned to these keywords -- if you're curious or need to tweak a special condition that is similar to one or the other of these).

    ... and one more to prevent some tricky loop:

    * !^X-Loop:

    (All of these patterns start with "bangs" (exclammation points) because the condition is that *no* line of the header start with any of these patterns. The 'bang' in this case (and most other regex contexts) "negates" or "reverses" the meaning of the pattern).

    ... now we add a "disposition" -- the autoresponse.

    | (formail -rk \
    -A "X-Loop:" \
    -A "Precendence: junk"; \
    echo "Please don't send me any more mail";\
    echo "This is an automated response";\
    echo "I'll never see your message";\
    echo "So, GO AWAY" ) | $SENDMAIL -t -oi

    This is pretty complicated -- but here's how it works:

    Most of the difficulty in understanding procmail as nothing to do with procmail itself. The intricacies of regular expressions (those wierd things on the '*' -- conditional lines) and shell quoting and command syntax, and how to format a reply header that will be acceptable to sendmail (the 'formail' and 'sendmail' stuff) are the parts that require so much explanation.

    The best info on mailbots that I've found used to be maintained by Nancy McGough (sp??) at the Infinite Ink web pages:

    More information about procmail can be found in Era Eriksson's "Mini-FAQ." at

    I also have a few procmail and SmartList links off of my own web pages.

    Copyright © 1997, James T. Dennis
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Utilizing the US Robotics Pilot with Linux
    by James McDuffie,

    Why the Pilot?

    There are a lot of Personal Digital Assistants available on the market these days. These include the Newton, Windows CE machines, and Psion. But the PDA being discussed here is the US Robotics Pilot. Before purchasing a PDA I thought carefully about a number of issues. These included cost, portability, and how well it could be expanded.

    The are a couple reasons why I purchased the Pilot. For one thing the Pilot is not very expensive. The Pilot comes in two different versions, called the Pilot 1000 and the Pilot 5000. These are the exact same except for the amount of memory they have loaded. The Pilot 1000 has 128k of memory while the Pilot 5000 has 512k of memory. What I did was purchase a Pilot 1000 and a 1 MB upgrade chip at the same time. This way I saved money in the long run than if I had purchased a Pilot 5000 and then later upgraded to 1 MBB of memory. The Pilot is considerably cheaper than other PDAs. Such as the Newton which is priced as under $800. The Pilot 1000 can be found for as low as $224 and the Pilot 5000 for as low as $269. The 1 MB upgrade chip can be found for as little as $89. Prices such as this make the Pilot a cost effective solution.

    Another issue was how portable the Pilot is. Carrying around a heavy PDA all day is not very comfortable. But the Pilot is very portable. It measures 4.7 x 3.2 x .7 inches, small enough to fit comfortably in your hand. The Pilot only weighs 5.7 ounces, with batteries. Because of this the Pilot can fit comfortably in your shirt pocket or your pants pocket. The Pilot's power supply is two 2 triple A batteries. These batteries can last you up to a month if you use the Pilot moderately. After all a PDA is supposed to help you, not burden you down by being bulky and heavy.

    The Pilot is very expandable too. Such is the case with the 1 MB upgrade chip that can be purchased from varies places. I find that 1 MB of memory is more than enough memory for my needs. The Pilot is also expandable in that you can upload any of numerous shareware or commercial applications for the Pilot. There is even a program that allows you to hook your Pilot up to a modem and dial into your ISP and then check your POP mail! These applications are very small. The average application made for the Pilot runs about 10k. With a 1 MB chip you could theoretically have 100 10k apps on the Pilot. The Pilot features a RS-232 serial connector on the bottom of it. The connector is used for syncing the Pilot with your desktop computer or for other uses. Other uses include hooking up a modem or hooking up a soon to be release wireless modem and pager. The Pilot can grow as your need for it grows.

    Using the Pilot with Linux

    Right now there is software available for use with the Pilot and Linux and other Unix flavors. You can obtain the software for use with Linux from:
    This software is still in development, but is highly usable. To use this software all you have to do is get the latest pilot-link package and untar/ungzip it. Once you have it expanded all it takes is to run the configure script and then do a make. You will then have about 16 programs depending on what version you have. I suggest that you install all of these programs into their own directory. I have mine installed in /usr/local/pilot and have included this directory in my path statement. This will make it easier for you to play around with the software. If you want to run the software as any user other than root, you will have to set them suid root. I have done this but restricted their execution to a group that only my login is a member of. This allows the software to execute the serial port.

    The software is simple enough to use. You simply supply supply the program name, the serial port and other information such as a filename. The pilot-xfer program allows you to install programs or data files that programs use into the Pilot. To install program all you would have to do is use the command pilot-xfer /dev/cua?? -i [program name]. After entering this your press the hot-sync button on the Pilot cradle and the Pilot installs the program. The program is then available for immediate use. Or if you wanted to install a text file into the memo you would simply enter install-memo /dev/cua?? [file name]. There are plenty of other programs that help you transfer information with other applications such as the date book, the address book and the to do list.

    For me, the name of these programs are pretty long and with typing the serial device name it gets tedious fast. So I set up a couple of aliases to speed up things. Some of my aliases are:
    alias pxi='pilot-xfer /dev/cua2 -i'
    alias im='install-memo /dev/cua2'
    These are the functions I use the most, because I hardly ever download applications from my Pilot since I already have them on my hard drive. The same goes for memos I install. But for the information that I create in the Pilot I use the sync-memodir program. It puts every memo in a separate fill. But the down side is that does not put the files in categories as they are on your Pilot. The up side is that the Windows software is not required.

    What to do if you do not have a free serial port

    One problem I encountered was that I did not have a free serial port. My mouse is on cua0 and my modem on cua1. For a while I had to switch the Pilot cradle with my modem. This was highly annoying because I could not use the modem while I was playing with my Pilot. I solved this with a $29 dollar ISA card I found at a local computer story, local as in locally owned and operated. The card is called the COM-5 card and is manufactured by Mouse Systems.

    The card is useful because if COM1 and COM2 are in use then COM3 and COM4 are not available. A COM port is simply a label that identifies a specific IRQ and address. COM1 and COM3 share the same IRQ as does COM2 and COM4. But this card allows you to add another serial port at any combination of IRQ and address that you desire. I have mine set on IRQ 12 and address 238. To get this to work with Linux all I had to do was tell Linux to map this specific address and IRQ combination to the device /dev/cua2. The following command does this:
    setserial /dev/cua2 port 0x238 irq 12 autoconfig
    It tell Linux where the serial port is available and to what device to map it. With this working I was able to play around with my Pilot while using my modem. Also I now have an extra serial port should I need it for other tasks.

    Logging in to a Linux computer via the Pilot

    Logging into a Linux computer via the Pilot is possible. It is not really that hard once you have the correct software. All you need is the application called Simple Term which can be obtained from Adam's Software Archive listed in the links section. Install the software on the Pilot and then make sure the Pilot is hooked up to the serial port. Run agetty on the serial device such as with this command:
    /sbin/agetty 19200 cua2 vt100
    And then put the Pilot in the cradle and hit online. You should then be able to talk with your Linux computer. The reason this works with the cradle is because the cradle is basically just a null modem hook up to the computer. Because of this a null modem adapter put on the cradle will allow you to use the Pilot on a modem, because of the fact that it reverses the null modem feature of the cradle. Logging into your Linux computer via the Pilot is not the most useful thing in the world since the program does not contain any terminal emulation. But it is possible which makes it fun.


    US Robotics Pilot Page
    Scott's Pilot Page
    Adam's USR Pilot Software Archive
    Aslan's Pilot PDA Links

    These links should be enough to learn about the US Robotics Pilot and how to use them. I hope this information will be helpful. If you have any questions what so ever, please contact me.

    Pilot-Unix Mailing List

    The pilot-unix mailing list is for discussion and idea-sharing for those interested in using the US Robotics Pilot PDAs with UNIX systems. This includes people who are interested in helping to develop tools to allow the Pilot to operate with UNIX, and possibly to develop an SDK for the Pilot for Unix.

    All postings to the list should be sent to the address

    Commands, such as subscribe or unsubscribe requests should be sent to the address

    Note that there are two list modes - normal (you receive each message as it is sent) and digest. The default mode is digest mode. To subscribe to the digest, send an email message with the single word "subscribe" in the message body to "". To subscribe to the normal list, use the word "subsingle" in the message body. You can also get a list of commands which the list server understands by sending mail with the single word "help" in the body to the -request address.

    If you have administrative questions or requests which require the intervention of a person, please send those to

    Copyright © 1997, James McDuffie
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Stronghold : Undocumented Fun

    By James Shelburne,

    Disclaimer: Secure Socket Layer technology is a pretty touchy legal matter. There's lots of money riding on it for a relatively small number of companies. Therefore keep in mind that what I say in this article may not be correct. If you plan to use Stronghold/Netscape (or any other SSL server/client pair) for inter-office communication get legal advice, or make sure you know what you're doing.
    Also I won't go into some of the knowledge that I think you already have, like the basics of public key cryptography or the fact that SSl URLs are https:// instead of http://.

    If you've looked for affordable ways to incorporate Secure Socket technology into your intranet you've probably run into Stronghold. Although Stronghold runs on platforms other than Linux it's a great, low resource intensive way, to use a spare Linux box for providing encrypted/authenticated document transfers over the Internet. This is perfect if you need to "network" separate offices over the Internet without worrying about prying eyes looking in on your document transfers.
    The main problem you face when trying to use Stronghold for inter-office communication is the lack of good documentation. Stronghold is mainly intended for companies who want to receive credit card orders on-line. As such, the installation scripts and documentation don't go into much detail about setting up Certificate Authorities (more on this later) and the features that allow you to not only have server authentication, but also client authentication as well. To clarify things a bit I'll give you a short "tutorial" on Secure Socket features. Since Netscape is the only browser that currently has a decent Secure Socket Layer (or SSL from here on out) implementation, I'll use that.

    Netscape Security

    Start up Netscape (3.0) and select Options -> Security Preferences. Click on the tab that says Site Certificates. This dialog box contains information about what Certificate Authorities your browser currently recognizes and what level of trust you have assigned to each. To illustrate this, select United States Postal Service CA and click the button that says "Edit Certificate..."
    Now you should see another dialog box pop up which contains various information on that particular certificate. Notice the two fields: "This certificate belongs to:" and "This certificate was issued by:". In both cases it contains the same information. This means that the certificate has been "self-signed" by the certificate owner.
    A little further down in the dialog box you'll see a pair of "radio buttons" that allow you to either accept or deny connections from secured Web sites that have been certified with this key. In other words, if you allow connections from sites whose keys have been signed by the USPS you're telling Netscape that you trust the USPS enough to certify SSL-enabled Web servers and that no further proof of a server's identity is needed. In reality, the USPS doesn't publicly certify keys (at least that I know of), we're just using that as an example. The final check-box tells Netscape to warn you before a secure connection is established to a Web server that has been certified by this key. Click "Cancel" to exit this dialog box.
    If you connect to a site that has not been certified by one of the CAs listed, all is not lost; you can still accept the individual site's key as an individual "Site Certificate."We won't worry about this method too much, but if you want to see which, if any, site certificates are installed in Netscape then select Site Certificates from the drop-down list above the "Site Certificate" list box. Note that, for some reason, Certificate Authority certificates are considered "Site Certificates."

    What you've looked at here is enough for basic electronic commerce. In other words, if you want to send sensitive information to a Web site, all you really need to know is that the site is who it claims to be. The Certificate Authorities listed provide this level of security. If you want to use your Web server to distribute sensitive information to select individuals, Server Authentication doesn't do you much good. Client Authentication gives you the ability to authenticate the clients who connect to your SSL Web server.

    Client Authentication

    Client Authentication of one of the neatest features of Netscape. In the previous screen, select the tab that says Personal Certificates. If you installed any Client Certificates (doubtful) they'll be here. If a server requests Client Authentication, Netscape can perform one of three actions:

    1. Automatically decide which Client Certificate to send the server.
    2. Let the user decide which Client Certificate to send to the server.
    3. Send a particular Client Certificate to the server.

    You can tell which action you want Netscape to perform by selecting the appropriate option from the drop-down list in the "Personal Certificates" dialog box.
    Client certificates can be purchased from various Certificate Authorities. This can get to be expensive if you want to certify multiple client browsers, not to mention a hassle. Luckily Stronghold comes with the basic tools that will allow you to create your own small-time certificate authority that you can use to certify clients who connect to your server and even other servers on your intranet.

    A look at the files

    There are lots of relevant files that Stronghold works with. I'll list the main, non-HTTP-specific ones. I'll also assume you have installed the program in the default directory (preferred).

    /usr/local/ssl/private/YOUR-SERVER.key This is your server's *private* key and should not be world-accessible at all. The way Stronghold installed the directory "private" is chmod 700 root.

    /usr/local/ssl/certs/YOUR-SERVER.cert This is where your servers *public* key is located. This should be world-readable, and in fact your server won't work in secure mode if it is not.

    /usr/local/ssl/CA/rootcerts.pem This file contains the public keys from the various CAs who issue Client Certificates. When your server wants to check that a Client Certificate is actually issued by a valid CA it looks in this file. This can be changed, but more on that later.

    /usr/local/ssl/CA/cacert.pem When you start your own CA this file will contain your public key. Note: This is not your server's public key.

    /usr/local/ssl/CA/private/cakey.pem The private key for your CA is stored here. As with all private keys, only root (or whatever username you administer your CA under) should be able to see or change it.

    /usr/local/ssl/CA/ssleay.conf AND /usr/local/ssl/lib/ssleay.conf For one reason or another, Stronghold has two separate configuration files. There is only a slight difference between them and Stronghold seems to want to use them both so I'll describe the files as if they were one and point out the differences as we come to them.

    The ssleay.conf file

    ssleay.conf is the main configuration file for Stronghold's key processing tools. It's relatively complex but fairly well commented out so I won't go into the whole thing, just a general overview and extra explanation where I think it's necessary.

    The thing that makes this configuration file different from what we've come to expect from Linux (and UN*X in general) is the way it's subdivided. If you've done much MS Windows programming you'll notice that it is divided into key=value pairs and most sections also have an "application name," for instance:

    [ policy_match ]
    countryName             = match
    stateOrProvinceName     = match
    organizationName        = match
    organizationalUnitName  = optional
    commonName              = supplied
    emailAddress            = optional
    In this section policy_match is the "application name" and the rest are standard key=value pairs. Here the whole section can be referenced by the label "policy_match"

    Selected fields (from ssleay.conf):

    default_crl_days: This "CRL" stumped me for a while. Apparently it has to do with Certificate Revocation Lists, a feature that is not really implemented in the SSleay toolkit (the package that was used to give Stronghold it's SSL capabilities). Actually that's not completely true, the CRL capability is there but CRL handling utilities aren't.

    policy: The "policy" field lets you select which policy you want to sign keys under. You probably won't need to mess with this since, in most cases, you will check and sign keys by hand. If you want to use a specific policy (check the Stronghold docs, what there is of them ;) ) change this field to "policy_match" and edit the policy_match section below to reflect your chosen policy. The two possible values: policy_match and policy_anything are "application names" of the sections of the configuration file that define who you will and will not sign keys for, or your "policy."

    distinguished_name: There is only one difference between the two different configuration files that Stronghold's key management tools use, and this is it. This key=value pair will point to one of two different "application names": req_distinguished_name or makeca_distinguished_name. The only time it will point to makeca_distinguished_name is when you are creating your own Certificate Authority, the rest of the time it will point to req_distinguished_name.

    [makeca_distinguished_name]: This and the next entry are not key=value pairs, but rather "application names" that define particular groups of information.
    The makeca_distinguished_name section of the file is only really referenced when you first create your CA. Also you do not need all of the fields that are included under this heading. For instance, when I made my CA key pair I removed both "organizationalUnitName" and "commonName." Because we aren't dealing with slick commercial software, it may object if you start altering this configuration file heavily.

    [req_distinguished_name]: This section of the config file is where information on machines to certify is kept. When you create a key-pair/signing request for your SSl server with genkey, default information is looked up here. Feel free to change some of the fields if you don't want this much info in your keyfile. Beware, some commercial key signers (i.e. RSA or whoever) may object to altered request formats. As before, your CA may choke if it gets a request that has been highly altered. One field to especial watch out for is "commonName," this is where Netscape looks to see if a web server is using an appropriate keyfile for it's domain name. For example, if Netscape tries to make a secure connection to and the keyfile that the server sends says it belongs to, you'll get a little dialog box warning you about a possible security problem. If no "commonName" is supplied, Netscape fails to connect and gives an error-message.

    The programs

    genkey:Genkey is the program that is used to generate an initial key-pair for your secure server and send out a signing request certificate to your chosen CA. Before you run genkey make sure and create backup of both your private and public keys for your Web server. After you make backups, delete the original keys as genkey won't operate if it finds that a key-pair already exists. Run the program like this:


    This will create a key-pair for your server and send out a Certificate Signing Request (or CSR). Since we are going to create our own CA and sign the key for the Web server with that, make sure that the CSR is sent to your own e-mail address and not Verisign. Now you have generated an initial key-pair and CSR. Get the CSR from your e-mail and save it for later.
    Also note that the defaults for genkey are had from the req_distinguished_name section of /usr/local/ssl/lib/ssleay.conf, if there are fields you don't want included in your keyfile remove them from this section.

    makeca: Makeca is the program that is used to actually create your Certificate Authority. This program gets it's default information from the file /usr/local/ssl/CA/ssleay.conf in the makeca_distinguished_name section (assuming you have installed everything in the default locations).
    Makeca is executed without any arguments and is actually pretty intuitive. As before, if there are entries that you don't want in your CA's keyfile just remove their entries from the makeca_distinguished_name section of the relevant configuration file.

    ca: Ca is the actual program that you will use to perform Certificate Authority functions. This includes signing other Web server keys and Netscape's client keys. Assuming that you have been following along up till now I'll assume that you have already used genkey to create a key for your Web server and that you have mailed the CSR to yourself. To sign your Web server's CSR save it as /tmp/csr and type the following:

    ca -config /usr/local/ssl/lib/ssleay.conf -in /tmp/csr

    ca will check the indicated configuration file to see what, if any, policy has been defined for signing keys and ask you for your CA password. After the key is signed it is stored in /usr/local/ssl/CA/new_cert/. New certificates are not stored by name but by serial number, with the newest cert having the highest number.
    The cert is stored in PEM (Privacy Enhanced Mail) format and as such, can be included in e-mail as is.

    getca: Once you have a signed certificate for your Web server you are ready to install it. Getca is the program for this and is called with:

    getca YOUR_SERVER_NAME < /tmp/cert

    We are assuming that /tmp/cert is your signed keyfile in PEM format.
    One of the odd things about getca is that the input file must be "piped" into the program.
    If this went correctly your Web server should now have a public key signed by your CA. Now for the tricky part...

    Making Everything Work

    Even though you now have a signed key certificate for your Web server you still can't use it. This is because Netscape isn't aware of your CA, this is to say that your CA isn't in the list of Site Certificates that we looked at earlier. To add your CA to that list follow these steps:

    1. Since the only (easy) way to install a key certificate in Netscape is through a Web server you'll have to add a new MIME type. I added mine to the mime.types file by adding a line like this:
      application/x-x509-ca-cacert       cacert
      There are other ways to add MIME types that don't involve messing with config files but I like the direct approach. Adding this MIME type tells Stronghold that every file that ends with a .cacert extension should be sent as a Certificate Authority's public key.

    2. The public key for your Certificate Authority is located in /usr/local/ssl/CA/cacert.pem. The only problem here is that it in in PEM format and Netscape expects CA keys to be in DER format. Luckily changing the format is pretty painless, simply move into the same directory as cacert.pem and type the following:
      x509 -outform DER < cacert.pem > cert.cacert
      Like getca, x509 requires input and output to be "piped." In any event your key is now in proper format and can be moved into one of your Web server's document directories.

    3. Now point Netscape at your freshly converted CA certificate (cert.cacert). Since you've added the appropriate MIME type Netscape will know that it is accepting a CA certificate and will lead you though the process of installing it.

    With that out of the way you should now see your CA's key when you look in Netscape's Site Certificates dialog box. Now, when you connect with your Web server, Netscape will find the CA who signed the server's key and try to locate it in it's database of CA certificates. Since we've just installed your CA's certificate, Netscape should accept encrypted connections from any site that has been signed by your CA.

    Client Certificates

    Creating Client Certificates for Netscape is a pretty complex task, and one of the least documented features of SSL. All of Netscape's Client Certificate functions work through a WWW interface, and as such you'll need two special files: a HTML and a CGI, here are both:

    open(TEST, ">/tmp/client_csr");
    $input =~ s/\+/ /g;
    $input =~ s/&/\n/g;
    $input =~ s/%2B/\+/g;
    $input =~ s/%2F/\//g;
    $input =~ s/%3D/=/g;
    $input =~ s/%0A//g;
    print TEST ("$input");
    print("Content-type: text/html\n\n$input\n");
    <TITLE>Make akey</TITLE></HEAD><BODY>
    <FORM ACTION="/cgi-bin/key_req.cgi" METHOD=POST>
    E-mail: <br>
    Common Name: <br>
    Organization Name:  <br><INPUT TYPE="TEXT" NAME="O"><br>
    Organization Unit:  <br><INPUT TYPE="TEXT" NAME="OU"><br>
    Locality:           <br><INPUT TYPE="TEXT" NAME="L"><br>
    State or Province:  <br><INPUT TYPE="TEXT" NAME="SP"><br>
    Country (2 letter): <br>
    <KEYGEN NAME="SPKAC" CHALLENGE="testkeygen"><br>
    <INPUT TYPE="submit" VALUE="Generate Key"></FORM>
    These files may need a little modification to work on your system, but they should work like this:

    keygen.html This is the actual HTML that Netscape needs to process a key request. Like many things in Stronghold's SSL key management utilities, you can omit just about whatever fields you want. For instance you might want to only create keys that have an e-mail address and a name, for this you would just remove everything except those two fields. This HTML was snagged from the SSL user mailing list archive at

    key_req.cgi This is the CGI program that will take Netscape's key request and format it into something that your CA can understand and sign. The script outputs two copies of the key request, the first goes to /tmp/client_csr and the second is echoed back to Netscape as text.

    Making A Signed Client Certificate

    To create a Client Certificate signed by your CA follow these steps:

    1. Assuming you have correctly installed both the CGI and HTML, load the HTML form into Netscape. From the drop-down list select the key-size that you want. If you are using the export version of Netscape you won't be able to choose a key size any larger than 512 bits. Fill in the fields with the desired information and select Generate Key. Netscape will lead you through the steps of creating your key. When you see the text of the client_csr echoed to the screen, you'll know that the script has been completed.

    2. Go into your CA directory and type:
      ca -spkac /tmp/client_csr -out /tmp/clientcert.der
      You'll be asked for your CA password and, if all goes well, a signed Client Cert will be output into /tmp/clientcert.der.

    3. As with installing CA certificates Netscape needs a special MIME type telling it that a particular file is a Client Certificate. Install this MIME type just like you installed the previous one:
      application/x-x509-user-cert              der
      This will tell Stronghold to use this MIME type for every file that ends in the .der extension.
      Whenever you change the configuration files you will have to restart the server so that the changes will take effect. Stronghold comes with a script called reload that does this for you.

    4. Move clientcert.der into a directory of your Web server and point your copy of Netscape at it. Netscape will then guide you through installing your new Client Certificate.
      As you do this keep in mind that you won't be able to make a key with one copy of Netscape and install the signed certificate in another. This is because every time Netscape makes a key it keeps various information in a database file. Because it is in a file you don't have to worry about creating the key and installing it in one session. You can even shut down Netscape and install the key the next day without running into any problems.

    After the certificate is installed select Options -> Security Preferences and click the Personal Certificates tab. Your new Client Certificate should appear in the listbox.
    If you're not the only person who has access to your machine, or even if you *think* that you are. It's a good idea to password protect your Client Certificate, this way someone won't be able to masquerade as you by simply having access to your computer. In Options -> Security Preferences, selecting the Passwords tab will bring up a dialog box that will allow you to password protect your copy of Netscape. If you set a password here it will will be used to actually encrypt your Client Certificate(s). Loose this password and you're out of luck.

    Client Authentication

    Unfortunately client authentication isn't very advanced with any SSL Web server package as of yet. In the future this will change so we might as well get comfortable with SSL technology now, even though parts can get pretty bumpy.
    First we'll go through the steps to enable reliable Client Authentication with Stronghold:

    1. Open Stronghold's SSL configuration file in a text editor (httpsd.conf).

    2. Enable SSLFakeBasicAuth. This will allow Stronghold to make limited decisions about who should be allowed access to the server from the information it gets from Client Certificates.

    3. Set SSLVerifyClient to 2. This tells Stronghold that it must always verify clients who want to connect to the server. If this isn't set then SSLFakeBasicAuth is pretty much useless.

    4. The SSLCACertificateFile directive tells Stronghold where to look for valid CA certificates for checking signed client keys. Normally this points to the file rootcerts.pem which contains public keys for a number of CAs that sign Client Certificates. It's very important to point this to your own CA's public key file, in this case cacert.pem. Doing this will only allow SSL connections from clients who have had their keys signed by your CA, if you are using this for inter-office work, you will want to do it this way.

    Stronghold handles users in a different and more limited way than what most webmasters are used to. For instance, in my Client Certificate I've only included my Name and e-mail address. This way, Stronghold identifies me with a string like this:

    /CN=James Shelburne/

    If you will look at the source for the HTML form above you'll notice that the "keys" are the same (i.e. CN for CommonName, Email for e-mail address etc.). If I had included other fields in my certificate, Stronghold would identify me by a larger list of "keys and values."

    Using SSLFakeBasicAuth

    To test out SSLFakeBasicAuth insert a line like this in Stronghold's SSL configuration file (Note: this only works in the SSL config file. SSLFakeBasicAuth doesn't work with unencrypted HTTP transfers)

    <Location /TEST_DIR>
    AuthType Basic
    AuthName Secret_Stuff
    AuthUserFile /usr/local/apache/conf/ssl_user_file
    <Limit GET POST>
    require valid-user

    The file /usr/local/apache/conf/ssl_user_file (or whatever file you choose to use) should contain the SSL identifier strings for each person that you want to be able to access your SSL server. If I wanted to set up my server so that I was the only one who would be able to access it, then the only line in my ssl_user_file would be:

    /CN=James Shelburne/

    When I try to make a secure connection to the server, Netscape will send the Client Certificate made earlier. Stronghold will see that SSLFakeBasicAuth is enabled and if I try and access /TEST_DIR, it will check the users in the AuthUserFile to see if I'm there. If I'm in the file I'll be granted access, if not, then access will be refused.

    If you want to control access for a number of different user groups, feel free to have multiple ssl_user_files each containing the identifying strings for the people in that group. You might have ssl_accounting, ssl_sales and etc.

    How do you find the strings that each user is identified by? When SSLVerifyClient is set to 2 and a person tries to access a directory on the server that is protected by SSLFakeBasicAuth the user string comes up in the file /usr/local/apache/logs/ssl/access_log. However, a better way to get the same information is through the use of CGI environment variables, in particular SSL_CLIENT_DN. Here's a short CGI script that when accessed through SSL will display the user's identifying string:

    CLIENT_DN displayer--------------------------------------------------
    print <<EOF
    Content-type: text/html
    <title>Your SSL_CLIENT_DN string</title></head>
    <h3>Your SSL_CLIENT_DN string is:<br></h3>

    There are other CGI environment variables but SSL_CLEINT_DN is the most useful. If you know your way around CGI programming you can automate your site on the basis of the SSL_CLIENT_DN variable.

    Copyright © 1997, James Shelburne
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Usenix/Uselinux in Anaheim

    By Phil Hughes,

    Usenix/Uselinux Photo Album

    Here I am at Usenix at the Mariott Hotel in Anaheim. Actually, it is pleasant to be in nice weather after almost drowning in Seattle. It had rained here the day before so the air was actually clean. But, let me talk about the show instead of the weather.

    Usenix is a five-day show that, this year, has a heavy Linux presence. For those not familiar with Usenix, it has been the "wear a tie and get laughed at" Unix show for years. It is technical and tends to draw a very seriously technical crowd.

    It is broken up into tutorials, a trade show and a technical conference. Well, plus the informal beer drinking sessions and such.

    Tutorial Days

    The first two days are tutorials and I elected to attend an all-day tutorial on the Linux 2.0 kernel presented by Stephen Tweedie. I found it to be excellent and that seemed to be the general opinion of the approximately 125 people who attended.

    In eight hours and 170 overheads, Stephen addressed four specific areas of the kernel: memory management, the scheduler, filesystems and I/O and networking. I feel the goal of the talk, "to be with the design and algorithms behind the Linux kernel and to be able to read the Linux source code with some understanding" was met. While Stephen did not necessarily expect attendees to be familiar with Unix systems programming, the more you knew about Unix the easier it was to understand the presentation. After all, learning all about a new operating system in eight hours is quite a challenge.

    On Tuesday, Ted T'so taught a tutorial on writing device drivers under Linux. This talk was attended by about 60 students. I elected to take Tuesday as a day to catch up on LJ work and make a run to Fry's Electronics to see if they carry Linux Journal. They don't--which makes no sense as Fry's is exactly the kind of place a Linux geek would want to go.

    Tuesday evening started with free food and drink. This is one of the best ways to get geeks talking. The Marriott did a great job with an array of food carts with various choices including fruit, veggies, potato patties, nachos, hamburgers and hot dogs. There were also drink and dessert carts. They even had my drug of choice, Dr. Pepper.

    There were Birds-of-a-Feather sessions scheduled from 6PM to 10PM. The two Linux ones were scheduled at the same time, both at 7PM. As I already know a lot about Caldera Linux I elected to go to the talk on Electronic Design Automation (EDA). Peter Collins, manager of software services for Exemplar Logic, headed the BoF and talked about how his company had done an NT port but now had a Linux port. He pointed out that EDA grew up on Unix-based systems like Suns and the capabilities of Linux were a better fit for current EDA users.

    The Trade Show

    The trade show started on Wednesday. While this was not a Linux-specific trade show, Linux had a large presence. Linux vendors included Caldera, EST (makers of the bru backup utility), InfoMagic, Linux International, Red Hat, Walnut Creek CDROM, Workgroup Solutions and Yggdrasil. Plus, of course, our booth where we were giving away sample copies of Linux Journal. Lots of other vendors came by to talk about Linux and the Linux products they sell.

    Linux interest was very high. While Usenix is a geek conference, these are mostly professional geeks who are making serious technical decisions for real companies. I answered many "It seems like Linux could do this" inquiries.

    Within the trade show I think SSC offered the biggest hit. We just finished our new "fences" t-shirt. We sold out of the shirts in about four hours on the first day. This gave me the feeling that I was at the right show--not one where Microsoft was being honored.

    Linus Talks and Linux Talks

    On Wednesday afternoon we proved how significant the Linux interest/presence was. Linus was scheduled to talk on the future of Linux in a fairly large room, which soon filled up, with standees everywhere--including the hall outside. Usenix quickly offered to move the crowd into a much larger hall.

    The talk went well as Linus explained new features and new ideas. I won't bore you with details. The important thing is that the goal is world domination. To some this sounded like humor. Maybe it was. Only time will tell. In the mean time, building a superior product can't hurt.

    Wednesday evening was a time for more Linux sessions. I attended one called The Classroom of the Future that showed how an experimental program brought the Internet to K-12 schools in Ireland. I also attended another called The Future of the Linux Desktop, missing Greg Wettstein's talk on perceptions. [see Greg's article "Linux in the Trenches" in LJ #5, September 1994--Ed.]

    Thursday was another day of talks and trade show. Peter Struijk, SSC's "head nerd" managed to make it to Victor Yodaiken' presentation on real-time Linux [see LJ #34, February 1997] and a talk on the /proc file system by Stephen Tweedie. In the evening, I hosted a session on embedded, turnkey and real-time systems and intended to make it to Developing Linux-based electronic markets for Internet Trading Experiments but ended up talking with some of the attendees of my session instead.

    The evening ended with a short talk about Linux and reality with Stephen Tweedie and then a trip back to the hotel room to finish up this column. Then, if I run out of things to do I may actually get some sleep.

    Friday offers a day of Uselinux business talks. However, the combination of editorial deadlines and exhaustion mean that you won't get to read about it here.

    What Next?

    It was a great show. Usenix has always been a great show offering high-quality sessions and a really nice mix of "non-suites". Having Usenix/Uselinux made it all the better. I am sure there will be serious cooperation between Usenix and Linux International to continue to make Linux a big part of Usenix.

    If I have one complaint it was that there was too much to do. Add a Linux International board meeting to a schedule that included sessions, talks and BoFs from 9AM to 11PM with parallel Linux tracks plus the normal Usenix tracks and there just wasn't time to breathe or, more importantly, sit down to a beer and talk to fellow kernel hackers, systems administrators or vendors.

    Anyone who wants to get copies of the Proceedings of this conference or find out what the future holds with regard to Usenix, should contact USENIX Association at or check out their web site at or, if all else fails, call 510-528-8649. Oh, and if you don't know what 8649 spells you must be new to the Unix community.

    Copyright © 1997, Phil Hughes
    Published in Issue 14 of the Linux Gazette

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    "Linux Gazette...making Linux just a little more lovable!"

    Welcome to The Linux Weekend Mechanic!

    Published in the February 1997 Edition of the Linux Gazette

    Copyright (c) 1997 John M. Fisk <>
    The Linux Gazette is Copyright(c) 1997 Specialized Systems Consultants Inc.

    Time To Become... The Linux Weekend Mechanic!

    You've made it to the weekend and things have finally slowed down. You crawl outa bed, bag the shave 'n shower 'cause it's Saturday, grab that much needed cup of caffeine (your favorite alkaloid), and shuffle down the hall to the den. It's time to fire up the Linux box, break out the trusty 'ol Snap-On's, pop the hood, jack 'er up, and do a bit of overhauling!

    Table of Contents

    Howdy! Welcome to the Weekend Mechanic

    Phew! It's good to be back!

    So how's everyone doing? How are things going? I had a great semester this past Fall -- got my 4.0 and everything :-) Still, things got rather hectic toward the end of classes and I'm still trying to get myself shoveled out from beneath a pile of backlogged email. I managed to survive six finals, the usual glut of "end-of-the-semester projects", a flight to Washington D.C. and a drive from there to N.Y. with my brother, his wife, and three small boys to visit our parents for Christmas, a new HD installation and complete system re-installation (the story of my life...), AND I actually managed to show my face at work once or twice before classes started again. If you're wondering why you haven't heard back from me, hang in there, I'm coming... :-)

    And is it only me, or does it seem that the 'ol Linux Gazette has really taken on quite a nice face lift since Marjorie Richardson took the helm...? I have to admit, the LG looks GREAT -- new graphics, better organization, a search engine, and so forth. Having worked on the LG in the past I know how much time and effort goes into each issue and I know that Marjorie has worked hard on this. I know that a lot of folks have taken the time to drop a note (the Mail section is as busy as it always was... :-) but if you haven't, you really need to! Here, let me make it easy for all of you with mail-capable browsers...

    See! that wasn't so bad, and the reality of it is that demonstrated interest and ongoing support are what keeps this 'ol ezine going in the first place! Remember: "The masses may vote with their feet, but hackers vote with both hands! (...unless you're able to type with your toes or are gifted with a prehensile tail or something... :-)"

    Anyway, drop Marjorie a note, she'll really appreciate it.

    Supermount for 2.x Kernels!

    I don't know about you, but one of the things that I really missed after doing the kernel 2.0 upgrade was being able to use supermount. For those of you who are unfamiliar with it, supermount is a program (in the form of a kernel patch) written by Stephen Tweedie that, in effect, allows you to insert, take out, and re-insert removable media such as floppies and CDs without going through all the rigmarole of using mount and umount. For those of us who are converts from the DOS era who are perpetually forgetting to umount a floppy before popping it out of the drive, this comes as blessed succor.

    And the good news is: IT'S BACK!

    Actually, it probably wasn't gone all that long, truth be known. I've been periodically checking in at the favorite mirror site and peeking around the /pub/linux/kernel/patches/ subdir for a newer version of supermount. No luck. Then recently, I saw a note posted by Stephen in response to someone's query that the program was available for the 2.0 kernels. To break the suspense, here's the URL:

    There's a patch for kernel versions 2.0.0 and 2.0.23 and a README file that outlines the fairly simple steps to applying the patch, recompiling the kernel (and speaking of forgetting to do things, if you don't do a 'make zlilo' then DON'T FORGET TO RERUN LILO if you install the new kernel), and setting up the needed /etc/fstab entry to start using it. For those of you who've used supermount in the past, you'll be pleased to know that the installation and setup haven't changed since the kernel 1.2.13 version -- you should be able to use your old /etc/fstab (if it's still lying around somewhere) and have things come up working like they did in the Good Old Days!

    Also, I wrote a short article on supermount several months ago for the LG and mentioned that I'd had a lot of trouble getting it to work correctly with the SoundBlaster 2X CD-ROM that I was using at the time. I was able to change CDs but the directory listing simply wasn't being updated correctly. Well, after the system upgrade this past Fall, I've switched to a Toshiba 8X CD and it works fine with this. Which reminds me...

    If you want to use supermount with a CD-ROM, at least with the ATAPI type drive that I've got, then you'll likely want to make a small change to one of the kernel files to allow the CD-ROM drive door to be opened when the drive has been mounted. As most of you probably have noticed, once you mount the CD drive, the door is locked -- you have to umount the drive in order to open it and change CDs. Obviously, this doesn't work well if the point to using supermount is NOT having to do this type of this. So, to disable door locking, and PRESUMING YOU'RE USING AN ATAPI TYPE CD-ROM, then edit the file:


    Look for the following section which is near the beginning of the file:

    /* Turning this on will disable the door-locking functionality.
       This is apparently needed for supermount. */
    #ifndef NO_DOOR_LOCKING
    #define NO_DOOR_LOCKING 0

    Change that '0' to a '1' after the NO_DOOR_LOCKING and you'll be all set. This, as the quick-witted will have already surmised, does what it implies: it disables door locking so you'll be able to change CDs. How about that for easy, eh?

    So, to summarize what you'll need to do, here's the brief rundown:

    1. get your hands on the supermount patch (I'll help you with this one in a minute...)
    2. apply the patch to the kernel:
      $ cd /usr/src/linux
      $ cp "path-to-patch"/supermount-0.4c-for-2.0.diff .
      $ patch -s -p1 < supermount-0.4c-for-2.0.diff
    3. edit the /usr/src/linux/drivers/block/ide-cd.c file to disable door locking
    4. recompile your kernel AND RERUN LILO (ever get the idea that I've forgotten to do this myself once or twice... :-)
    5. edit your /etc/fstab to enable mounting of floppy or CD-ROM drives via supermount
    6. reboot the system to load the new kernel and enable supermount
    7. Enjoy!!

    Now, for the trusting (or merely lazy like myself... :-), here's a copy of the patches and the README file:




    If you're the suspicious or just plain cautious type then go ahead and get the files from the URL above. Also, you might want to check there for updates or newer releases.

    One thing that I've not really tried yet is seeing what happens if the CD-ROM drive is mounted via supermount and you attempt to play an audio CD. I've not had the nerve to try this. In this case, it's probably safe to go ahead and umount the drive, play the CD, and then mount the drive once again -- since there's an entry for the CD-ROM drive in /etc/fstab, all you should have to do is something like:

            mount /cdrom
    presuming that /cdrom is where you normally mount your CD.

    The other thing that I've not tried is using supermount with BOTH ext2 and MS-DOS type floppies. I suspect that it would cause a bit of trouble but, again, I've not been daring (or foolish...?) enough to try this little maneuver.

    Anyway, I hope that give supermount a try! The README file is pretty helpful in terms of answering basic setup and usage questions and he includes a copy of his /etc/fstab file as an example. Hope you enjoy!

    Nashville, TN
    Mon Jan 20 10:26:51 CST 1997

    DOSEMU and WP 6.1 for DOS...

    I hesitate to even bring this up... :-)

    One of the more common USENET postings in almost any of the linux groups these days is some newbee who innocently ventures a question such as "Is there a word processor for Linux like Word for Windows...". After the poor bloke gets flamed to a crisp with ardent admonitions to eschew such lollipop-ware and use a real text-processing system such as LaTeX or GROFF, there usually ensues a heated debate over the virtues of one's favorite system for getting something into print...

    I think I'd like to avoid such debate... :-)

    I would, however, like to humbly offer one possible solution to the need for a word processor under Linux -- especially if you're either unfamiliar with LaTeX or find that it doesn't completely meet your text-processing needs. And that is, using DOSEMU and one of the common word processors available for DOS. Now, if you already have a system working for you then by all means stick with it! However, if you still find yourself rebooting to DOS, OS/2, or Windows to do a bit of word processing then this might be one possible alternative.

    But before I go on...

    Let me quickly mention that I'm well aware that the usual business apps which have long been available for the other OS's -- the word processors, spreadsheets, desktop publishing packages, PIMs, and so forth -- are starting to appear as Linux-native applications! This is great news and I certainly welcome and support such efforts to bring these much-needed tools to the the Linux OS! Thing is, what I've tried so far really hasn't been helpful for me. To wit:

    I really don't want to get mired down in a review of all the possible word processor tools out there -- I mention these in order to say, "I've given them a a try..." Two other applications that really deserve to be mentioned include the Caldera's WordPerfect for Linux and the Applixware Suite available through Red Hat Software. I've not had a chance to try either of these out, although I've read a good deal of pro's and con's about each of them in the linux USENET hierarchy. A buddy at school just got a copy of the academic version of Applixware and I'm pretty interested in seeing this in action. So far, he's been pretty pleased with it, so I definitely need to stop by and give this a try!

    Anyway, what I've found is working quite well for me is a combination of DOSEMU and WordPerfect 6.1 for DOS. If you happen to have an old (or new) copy of WP for DOS available to you, and you're willing to give DOSEMU a whirl, let me urge you to give this a try.

    At this point, I'm going to do something I swore to myself I'd never do -- I'm going to weenie out on you a NOT go through the entire process of setting up DOSEMU. The reason for this is that, although I've gotten it up and running on my own box at home here, I really don't feel terribly comfortable with being able to walk anyone else through the process. I ended up tinkering around with it and, through an admittedly haphazard process of trial & (mostly) error, got the thing to work. There are still several things about it that I don't understand and so I won't inflict my ignorance upon you.

    Still with me... :-)

    Thing is, there's a very helpful little file that comes with DOSEMU called "QuickStart" that goes through the setup process step-by-step. If a Neanderthal like me can get this working, I'm confident that you can too!

    What I would like to do is present a brief synopsis of my experiences with this in the hopes that it might be helpful to someone trying the same things. Again, let me emphasize that this represents strictly my own experiences. As the old saying goes, "your mileage may vary..."

    DOSEMU Setup

    After upgrading to kernel 2.0 I found it necessary to upgrade a number of packages, including DOSEMU. At the time, I picked up the most recent version which was dosemu- The configuration, compilation, and installation were as simple as:

            $ ./configure
            $ make
            $ make install
    This defaulted to including DPMI support, requiring the emumodule and syscallmgr modules to be loaded before being able to use DOSEMU. DPMI support allows you to try your hand at booting up Windows under DOSEMU. Over the past few months I've had mixed success at best in doing this. Also, since this is not currently supported by the DOSEMU folks, you're completely on your own if you want to venture into this! :-)

    After compiling and installing the binaries, I used the QuickStart file as a guide and created the needed /etc/dosemu.conf and /etc/dosemu.users files. DOSEMU comes with a heavily commented configuration file -- dosemu.conf -- that let's you customize in a rational manner. For the curious, here's my current working version of dosemu.conf:

    /etc/dosemu.conf example file

    Let me make a couple comments about this before going on:

    After doing all of this (in an incremental fashion) I found myself with a working version of DOSEMU and a functional WP program!

    I also decided to load the emumodule and syscallmgr modules at boot time so that I could use DOSEMU more easily. To do so, you'll probably want to the use 'insmod' program that gets compiled with the rest of the DOSEMU files. The easy way to do this is to use the '' script in the root DOSEMU directory. I found that by editing the first couple lines of the script I was able to call it from any directory: just add the correct path names at the top:

    and then add a stanza to /etc/rc.d/rc.local such as:
    if [ -x /usr/local/lib/dosemu- ]; then
            echo "Loading DOSEMU 0.63 modules..."
            . /usr/local/lib/dosemu-
    The modules use up very little memory and the convenience of not having to remember to load them is probably worthwhile.

    Installing WordPerfect 6.1 for DOS

    There really isn't an awful lot of startling news here -- if you're used to installing DOS programs then this is pretty much a "no-brainer". The one important point to make, however, has to do with video driver installation. I discovered something quite valuable recently when I re-installed my system over Christmas Break.

    The first time I set up WP 6.1 I installed only the S3 drivers (since I'm using an S3-based Diamond card). I found that doing so provided graphics mode support under DOS in resolutions up to 1280x1024. However, I was keenly disappointed to find that the best graphics-mode resolution I could get under DOSEMU was an abysmal 320x200. No matter how I poked, prodded, wheedled, cajoled, threatened, and messed with it, that's all I got.

    Serious Bummer... :-(

    Over Christmas, when I reinstalled the system, I noticed that one of the video drivers was labeled simply "VESA" and so, on a whim, installed that as well as the S3 drivers. This turned out to be quite fortuitous as although the S3 drivers still did not give better than 320x200 resolution, the VESA driver actually allowed me to get 1024x768 in 8-bit color. On a 17" monitor, this is a very comfortable resolution and provides pretty good WYSIWYG previewing.

    So, the moral of the story is -- if you're in doubt, give the VESA video drivers a whirl.

    Running WordPerfect 6.1 under DOSEMU

    Once I got DOSEMU installed and properly configured (BTW, I also created the /etc/dosemu.users file that simply has the word "all" as the sole word on the first line -- this let's anyone (i.e., me) to execute the program) and WP 6.1 installed, I was quite pleased to discover that nearly all the features available from running it under DOS were also available under DOSEMU:

    The one feature that I haven't yet tried is fax support, although ostensibly it should work.

    A feature of WP that is completely UNAVAILABLE under DOS is that I can be editing a file in WP under DOSEMU and, using Ctrl-Alt-Fn, switch to another virtual terminal and continue to work under Linux. Running X Window concurrently also has shown no signs of causing problems.

    Let me say this again since I get a chill just thinking about it...

    I can run DOSEMU + WP 6.1 in a virtual terminal and have full editing and printing capabilities while at the same time freely switch to another VT or even to X Window and have all these processes running concurrently!!

    This is what makes Linux such a seriously cool OS!!

    This is way too cool... ;-)

    The one caveat I'd mention is that of using WP in graphics mode. I don't know about WP 5.1, but version 6.1 supports a fairly respectable graphics-mode that provides WYSIWYG editing and print preview. On my system, the performance is quite acceptable, although not quite as responsive as under DOS (but then who'd want to run anything under DOS if they didn't really need to... :-) However, switching to a VT or to an X Window session while in graphics mode renders the system completely unusable -- the keyboard AND the console both go into impenetrable lockup which only a cold boot fixes. This has, at least, been my experience. However, I found that if I simply exited back to text mode before switching to another VT then everything worked fine.

    Finally, let me make one last comment about using WP under DOSEMU. One of my ongoing complaints about many (though certainly not all) of the current "word processors" available for Linux is the quality of the printed output. The features that drew me to using WP were the familiarity with the program and the quality of the final output. WP 6.1 supports, among other things, TrueType fonts and having invested in a Corel Draw some time back (and its 750+ TT fonts) I was pretty keen to being able to continue to use these. I've been quite pleased that under Linux I can still do basic word processing in a known environment with predictable output. That was the clincher for me.

    Again, let me quickly add that this might not be at all what you want or you might simply dislike the WP system itself. The thing about Linux is that it give you a choice once again!

    And, for the skeptics out there, those who said, "it can't be done...", here's a screen shot of WP 6.1 running under X...

    screen shot of WP 6.1 running under xdos

    Give this a try! If you like it, keep it. If not, delete it and have a look at something else. Also, if you're looking for something to run under X then you might be well served to give either the Applixware suite or the Linux WordPerfect port a try. DOSEMU will run under X (as xdos) but WP loses some of its functionality -- mouse support and keystroke support can be a bit flaky and graphics-mode support is completely lost. So, if X is where you spend most of your time, you might consider investing in or investigating one of the native X programs.

    Most of all, though...

    Have Fun & Happy Linux'ing!

    Nashville, TN
    Mon Jan 20 13:18:01 CST 1997

    X Window Wallpapering...!

    Well, here's a little nothingburger that comes pretty close to being a bona fide FAQ -- the question arises from time to time as to how to (automatically) wallpaper one's X Window session after starting X. For the impatient, the short answer is:

            xv -quit -root image.gif
    Presuming, of course, that the image that you wanted to use was in fact called "image.gif" the above would use the ubiquitous xv program by John Bradley to tile your root window with the specified window. The "-quit" option causes xv to do its work and then quietly terminate.

    If you're using one of the 1.x versions of FVWM then just add a stanza such as the following:

    Function "InitFunction"
            Exec  "I"  exec /usr/X11/bin/xv -quit -root /usr/gx/image.gif &
    That is, you simply add a stanza for xv to the "InitFunction" and this is done automatically!

    Since I've not upgraded to the newer FVWM 2.x version (nor FVWM-95, or any of the other myriad new window managers) you're rather on your own with this one. However, I suspect that a quick perusal of the manual page or the configuration file should quickly point the way.

    At the moment, I'm using olvwm 4 (with the 3.2 libraries) and added the following to the /var/openwin/lib/Xinitrc file:

    # Xinitrc executed by openwin script to display startup logo
    # and restore desktop setup (saved using owplaces)
    # Hereby placed into public domain by Kenneth Osterberg 1993.
    # Start programs
    exec /usr/X11/bin/xv -quit -root /var/openwin/lib/marbleFlowers.gif &
    exec /usr/local/X11/bin/xcalendar -geometry 240x240+0+160 &
    exec /usr/X11/bin/xclock -geometry 134x127+252+0 &
    exec /usr/local/X11/bin/rxvt -ls -font 9x15 -geometry 80x32+500+195 &
    exec /usr/local/X11/bin/rxvt -ls -font 9x15 -geometry 79x31+252+268 &
    exec /home/fiskjm/bin/syslogtk -geometry +398+0 &
    # Startup the OpenLook window manager
    if [ ! -z "$WINDOWMANAGER" ]; then
            exec $WINDOWMANAGER
            exec $OPENWINHOME/bin/olwm
    This has the identical effect of tiling the root window before olvwm is launched.

    If you're interested in this, there are actually all sorts of nifty things that you can play with along this line. Keep in mind that xv has a plethora of options for setting the root window image interactively. To do so, simply find an image that you'd like to play with, launch xv with the image filename as the argument, and then select the "Root" button. I won't list all the possible options -- try them out and amuse yourself!

    Thing is, to really have a good time you need to have a few images to play with and question is, where to get these little rascals...?


    Here's a couple ideas to get you going:

    Anyway, you get the picture. If you have a scanner, then you're golden :-)

    So let's do a quick walk through on this.

    After I somewhat reluctantly installed Win95 this past Fall (I was taking a Visual Programming class and you can guess as to which Visual language we had to use...) I discovered a few new wallpaper images including one that I really liked -- the Forest.bmp image. I happen to enjoy hiking around in the nearby Great Smoky Mountains and grew up in the pine forests of upstate New York. Anyway, I decided that I'd gotten a bit tired of the 'ol SteelBlue background and was ready for a change. Here's what I did...

    After mounting my Win95 partition and copying the c:\win95\Forest.bmp file to my home directory I used xv to have a look at this rascal and convert it to a GIF image. XV allows you to save an image as any number of different formats and I chose GIF, Full Color. That done, I had a suspicion that this might be a bit of a color resource hog -- a suspicion that was confirmed by another handy little program, xli.

    Xli is a graphics manipulation program that is easily found at any of the sunsite mirrors in the X11 directory under the graphics viewers subdirectory. One of its handy features is the "identification" mode that it can run in. To get information about an image (from the command line) simply type in:

            xli -ident image.gif
    and assuming that the image you were interested was, in fact, named "image.gif" then it would print out a useful one-liner. Doing this to the Forest.gif image that we just created using xv, we find:
    $ xli -ident ~/Forest.gif
    /home/fiskjm/Forest.gif is a 256x256 GIF87a image with 256 colors
    Hmm... the size is OK, but with 256 colors this will definitely burn out my color map quicker than you can say Netscape! Now, enter the next useful program to our arsenal of image tools -- ImageMagick.

    ImageMagick is one of those seriously cool, Must-Have programs if you're playing around with images very often. I recently found the latest version (nicely pre-compiled, thank you...) at the GA Tech sunsite mirror (ImageMagick-3.7.9-tgz) along with the needed libraries (libIMPlugin-1.0-tgz). Installing the precompiled bin's was a no-brainer and I was up and running in no time flat.

    One of the programs that is included with ImageMagick (it's actually a suite of programs) is convert. convert allows you to quickly and easily convert images from one format to another and to optionally set its various attributes. You need to have a look at the manual page (which is included with the binaries) to really appreciate all the things this is capable of doing. For what I was trying to do, all I needed was to set the size of the color map to something a bit more sane.

    Using the "-colors" option I was able to set the "preferred number of colors" to something that was a bit more X friendly:

            convert -colors 32 ~/Forest.gif ~/forest.gif
    Doing this and running xli on it once again, we find that it has, in fact, been stripped down to a more lean 32 colors:
            xli -ident ~/forest.gif
            ~/forest.gif is a 256x256 interlaced GIF89a image with 32 colors
    That's a bit better. Now I suppose that I could have used an even smaller number but 32 colors gave an image that differed visually from the original image very little.

    Anyway, that was it! I now had a 256x256 image with 32 colors that no longer threatened to burn out my entire color map! I added a stanza to the Xinitrc file and voila!, instant wallpaper!

    Keep in mind that this is hardly the only way to do this. There are several other nifty programs out there that provide similar functionality. Try scrounging around in the X11/graphics/ subdirectory of any of the sunsite mirrors or at in its contrib subdirectory.

    Another program that I'll mention before closing this up is the truly awesome xearth program. If you're looking for a truly impressive, animated X wallpaper program, look no further. This is one way too cool program! I don't have a screen shot of it to show you but believe me, it's worth setting it up and giving it a whirl! At the moment, you should be able to find it in the /X11/xapps/graphics/ subdirectory of any of the sunsite Linux mirrors. The file to look for is xearth-1.0.tgz.

    Anyway, hope this gets you going! I admit that it's been a bit of a smorgasbord of suggestions, but you might be able to find something useful here! :-)

    As usual, hope you enjoy!

    Nashville, TN
    Mon Jan 20 21:08:25 CST 1997

    Closing Up Shop...

    Well, as usual, things around here have been busier than I'd hoped and I just don't have the time to do all of the writing that I'd like to. Also, I'm trying to keep this page to a reasonable size :-) (those of you who've been hanging around here for a while might remember those 160K+ size pages...).

    So what has everyone been up to? Found any new toys... :-)

    Over Christmas, I finally started working on something that I'd been promising to do for ages: I've started to learn emacs! I have to say that this has been a bit of a paradigm shift after having used VIM for such a long time. However, I can see why the loyalties run so deep -- Emacs is a seriously cool and indisputably powerful editor. Truth is, however, that I've not taken the purist approach: I have to admit that I'm really using XEmacs. I also got my hands on an xemacs-derivative called infodock which is another way-too-cool and VERY powerful editor.

    I'd hoped to write a bit on my initial experiences and impressions but I guess that will have to wait for another month or so. Thing is, there are actually quite a number of GREAT editors out there to mess around with. And the more that I try out different ones (I've decided that I really am an "editor junkie...") the more I'm convinced that the essence of the editor flame wars that periodically erupt can be summed up in preference.

    Not to throw a wet blanket on anyone's jihad, but...

    Although feature sets, user interfaces, resource utilization, performance issues, and so forth are very valid issues when discussing the various merits and liabilities of one's favorite editor, the bottom line is: you probably use it because you like it! I have to admit that after using VIM for the past couple years, emacs is something of an acquired taste. However, if you've been using emacs for a while, then vi looks a bit stark and your fingers feel bewildered.

    Anyway, there's no accounting for taste and no apologies for it either. The great thing about Linux is that "it restores the choice once again!" Try everything out, use what is useful, keep what you like. And FWIW, those of you using a VI clone like myself might be interested in giving the latest iteration of VIM a test drive. As of a little bit ago, VIM 4.5 source was in the sunsite Incoming directory. It can now be compiled, using the Motif widget set, to have both a console-based and an honest-to-goodness X-based interface. The X version is called gvim (for "Graphical VIM") and I'm using it right now. It has all of the usual keystrokes (for all you ten-fingered typers...) but has nice mouse support for cursor positioning and cut-and-paste operations. It also sports a handsome scrollbar, handles multiple windows with aplomb, and even touts a rudimentary but useful menu bar. It has a very extensive online help system that is vaguely hypertext-like: you can navigate from one "node" to another using a keystroke similar to that with tags: Ctrl-] selects a node and Ctrl-t returns you to the original location.

    With any luck, I'll have some time this next month and will try to put something together -- mostly just chat, nothing terribly profound. I've got a few screen dumps for the visually-oriented. Those of you who are considering taking the leap and learning emacs might well be served to have a look at this rascal. AND, keep in mind that it is NOT just an X Window app -- it'll run in console mode just as easily as under X. Have a look at the XEmacs home page for more info:

    And while you're there, have a peek at the infodock stuff as well. Finally, in this month's Linux Journal there's a very nice article by an old LG regular: Larry Ayers, who has written a review comparing GNU Emacs with XEmacs. For the curious, it's well worth having a look at what Larry's impressions of the two were.

    Well, I've got a bit of work to get one tonight and so I'll wrap this up for the month. I'm still trying to get out from underneath a pile of email. Hang in there... I'm coming!

    Best Wishes and Happy Linux'ing!!

    John M. Fisk
    Nashville, TN
    Monday, January 27, 1997

    If you'd like, drop me a note at:

    John M. Fisk

    Version Information:
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    Copyright © 1997, John M. Fisk
    Published in Issue 14 of the Linux Gazette

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    Copyright © 1997 Specialized Systems Consultants, Inc.
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    About This Month's Authors

    Larry Ayers

    Larry Ayers lives on a small farm in northern Missouri, where he is currently engaged in building a timber-frame house for his family. He operates a portable band-saw mill, does general woodworking, plays the fiddle and searches for rare prairie plants, as well as growing shiitake mushrooms. He is also struggling with configuring a Usenet news server for his local ISP.

    John M. Fisk

    John Fisk is most noteworthy as the former editor of the Linux Gazette. After three years as a General Surgery resident and Research Fellow at the Vanderbilt University Medical Center, John decided to "hang up the stethoscope", and pursue a career in Medical Information Management. He's currently a full time student at the Middle Tennessee State University and hopes to complete a graduate degree in Computer Science before entering a Medical Informatics Fellowship. In his dwindling free time he and his wife Faith enjoy hiking and camping in Tennessee's beautiful Great Smoky Mountains. He has been an avid Linux fan, since his first Slackware 2.0.0 installation a year and a half ago.

    Jim Dennis

    Jim Dennis is the proprietor of Starshine Technical Services. His professional experience includes work in the technical support, quality assurance, and information services (MIS) departments of software companies like Quarterdeck, Symantec/ Peter Norton Group, and McAfee Associates -- as well as positions (field service rep) with smaller VAR's. He's been using Linux since version 0.99p10 and is an active participant on an ever-changing list of mailing lists and newsgroups. He's just started collaborating on the 2nd Edition for a book on Unix systems administration. Jim is an avid science fiction fan -- and recently got married at the World Science Fiction Convention in Anaheim.

    Grant B. Gustafson

    Grant Gustafson is Professor of Mathematics, the University of Utah, Salt Lake City. Besides differential equations, he has an interest in microcomputers (since 1978), compilers, programming languages, system utilities and TeX typesetting.

    Michael J. Hammel

    Michael J. Hammel, is a transient software engineer with a background in everything from data communications to GUI development to Interactive Cable systems--all based in Unix. His interests outside of computers include 5K/10K races, skiing, Thai food and gardening. He suggests if you have any serious interest in finding out more about him, you visit his home pages at You'll find out more there than you really wanted to know.

    Phil Hughes

    Phil Hughes is the publisher of Linux Journal, and thereby Linux Gazette. He dreams of permanently tele-commuting from his home on the Pacific coast of the Olympic Peninsula. As an employer, he is "Vicious, Evil, Mean, & Nasty, but kind of mellow" as a boss should be.

    Mike List

    Mike List is a father of four teenagers, musician, printer (not laserjet), and recently reformed technophobe, who has been into computers since April,1996, and Linux since July.

    R. Frank Louden

    Frank Louden has a degree in Computer Science from Purdue. While working on his degree, he also worked in the Medical center first as a Computer Clerk then as the Systems Manager. He currently works as a Programmer, which "is all the fun and a lot fewer headaches (read: It sounds like a hardware problem to me.)" He first installed Linux last March, so he knows the challenge a convert faces. On the personal side, he lives in a small town in north central Indiana and would love to organize a LUG but thinks it'd be difficult to find any other Linux users out here in the boonies. He has two cats, Mac and Catalina who he says "both know more about Linux than I do...but they never reveal their secrets!"

    James McDuffie

    James McDuffie is a 17 year old high school student who is looking forward to graduating. In college he plans to major in Computer Science and minor in English. He would like to be a writer while still working with computers. James wrote the article Connecting Computers via PLIP which appeared in issue #6 of the Linux Gazette. He has been an avid reader of the Linux Gazette ever since it was just starting out. And wishes that it continues helping the Linux community for some time to come.

    James Shelburne

    James Shelburne currently lives in Waco, Texas where he spends most of his free time working on various Linux networking projects. Some of his interests include Perl + CGI, Russian, herbal medicine and the Ramones (yes, you heard right, the Ramones). He is also a staunch Linux advocate and tries to convert every MacOS/MS Windows/AMIGA user he comes into contact with. Needless to say, only other Linux users can stand him.

    Kelley Spoon

    Kelley Spoon currently studies computer science at the University of Texas, San Antonio. Some of his hobbies include trying to learn how to play the guitar, playing Euchre, laughing at John C. Dvorak, converting pizza into source code, terrorizing villages along the Mexican border, and frightening small childern. He has been a Linux user since August 1995, and still pronounces the name as "luh-eye-nucks". Kelly has written another article for us about tcpd that will appear in issue 15 of Linux Gazette.

    Jens Wessling

    Jens Wessling is a 26 year old Research Scientist working for the Environmental Research Institute of Michigan. He has been playing with Linux since Kernel 1.0.99. He is married and has 2 cats. He is currently working on his Masters Degree in Computer and Information Science at the University of Michigan. Life frequently gets in his way.

    Joel Wilf

    Joel Wilf is a technical writer with a strong interest in computers and multimedia. He is also a screenwriter, whose credits include Supercarrier and Outsiders. Writing a script-formatting utility, under DOS, led him to the richer programming and text-processing environment of Linux. Offline, he enjoys reading and traveling. He lives in Encino, California.

    Not Linux

    Thanks to all our authors, not just the ones above, but also those who wrote giving us their tips and tricks and making suggestions. Thanks also to our new mirror sites. We get new ones every month. I was very excited to have both one in Russia and the new Italian translation site go up this month. (See the Mirror Page.)

    My two favorite holidays are Valentine's Day and Halloween. Not sure I want to know what that little fact may have to say about my psyche. At any rate I hope the animated heart wasn't too annoying. I thought it was quite cute. Thanks to Michael, our web guy, for finding it and the roses to present to our authors.

    Two days after Valentine's on February 16, Riley and I will be celebrating our 5th wedding anniversary. In fact, we're celebrating all weekend -- a long one with the holiday -- by leaving town and telling no one where we are going. Riley is a very special guy, and we've had a great 5 years. I look forward to many more with him.

    February 16 is also the birthday of my nephew Alex Carter. He's 14 and working on his Black Belt in Tae Kwon Do. He's a smart kid and loves playing on his computer. I need to find the time to introduce him to Linux.

    On a professional note, I am now Managing Editor of Linux Journal as well as Linux Gazette. Gary Moore and I have switched jobs--keeps things from getting boring. However, I refused to give up custody of Linux Gazette, it's just too much fun.

    Have fun!

    Marjorie L. Richardson
    Editor, Linux Gazette


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    This page written and maintained by the Editor of Linux Gazette,