Introduction to Tcl/Tk

Pete R. Jemian
University of Illinois at Urbana-Champaign

Tool Command Language (TCL or Tcl) is a software package that can be used to provide a consistent user interface to new or legacy software. Sun Microsystems is dedicated to the maintenance and upgrades of Tcl by hiring its creator, Dr. John Ousterhout. One example of a Tcl application is the Sun Solaris operating system installation software. According to the Sun web page for Tcl (

"The core Tcl and Tk libraries are distributed freely in C source code form, and in binary form for the Macintosh and PC. The libraries run on all UNIX, Macintosh (68k and Power Mac), and Windows (3.1, NT, and 95) platforms."

A version of Tcl for VxWorks has also been found on the WWW. Documentation for Tcl is widely available on the WWW, network news groups, online help documentation, and even commercial bookstores.

Tcl is popular for user group software because it is easy to write and debug the scripts in the Tcl interpreter. Tcl can be embedded into a compiled application to add scripting capability. Alternatively, user's can compile C or C++ functions and add them to a Tcl interpreter. Many examples of the latter can be found on the Tcl contributed archive site (

The most popular Tcl extension is Tk, used for creating graphical user interfaces. Other extensions add interface builders, 2D and 3D charting, WWW browsers and servers, UNIX file browsers, text editors, email readers, games, serial I/O, TCP socket I/O, timeouts, ...

(posted 3-Dec-97 jw)