You can connect to ASE and perform SQL commands in all common computer languages.
C / C++
Sybase provides client development libraries under the name of Open Client Developer's Kit which is included in their SDK. There is also an Embedded SQL/C precompiler which enables you to add SQL code to your C programs
If you prefer to use free / open source products, there is the FreeTDS project at http://www.freetds.org/. This is a re-implementation of Sybase's Tabular Data Stream (TDS), used for the client-server communication.
Note that Microsoft has modified their SQL Server TDS dialect from their Sybase legacy and you are no longer guaranteed that Microsoft SQL Server clients can communicate with a Sybase server or vice versa. MS SQL Server 6.5 came with a patch to enable Sybase TDS compatibility, later versions (7.0, 2000) do not support the Sybase communication protocol.
Java / JDBC
Sybase ships the jConnect JDBC driver with ASE for Linux in ASE 12.5.0.x and up. There are both JDBC 1.0 and 2.0 implementations, labeled as jConnect 4.x and 5.x respectively. These are Type 4 JDBC drivers, which means they are 100% Java implementations of the TDS protocol.
The FreeTDS project mentioned above also ships a JDBC driver.
For Windows clients, the ODBC drivers are shipped on the "PC Client CD". This used to be a ODBC layer on top of the Open Client runtime libaries, but are being modified to speak TDS directly instead.
There is also an ODBC driver available from FreeTDS. Unfortunately, it appears there is no unixODBC (http://www.unixodbc.org/) driver available yet.
You can use any of DBD::Sybase, DBD::ODBC, DBD::FreeTDS or Sybperl with the FreeTDS libraries. These modules are available from CPAN. You can find lots of details from Michael Peppler's site, http://www.mbay.net/~mpeppler/.
A Python module for connecting to ASE (and documentation for it) can be downloaded from http://www.object-craft.com.au/projects/sybase/
PHP includes Sybase connectivity, based on the Open Client libraries. The PHP manual shows examples on connecting to an ASE server, sending queries and handling the result sets. See http://www.php.net/.
An extension for connecting to ASE from tcl is available from http://www.nyx.net/~tpoindex/tcl.html