FreeTDS (free implementation of the Tabular Data Stream protocol)

FreeTDS is a free implementation of Sybase's db-lib, ct-lib, and ODBC libraries.
FreeTDS builds and runs on every flavor of unix-like systems we've heard of, as
well as Win32 (with or without Cygwin), VMS, and Mac OS X. Failure to build on
your system is probably considered a bug. It has C language bindings, and works
also with Perl and PHP, among others.