Tcl is used quite heavily as a command line shell EDA tools. Google "pt_shell tcl" or "ncsim tcl" for examples. Cadence and Mentor Graphic's digital simulation

Tcl is used quite heavily as a command line shell EDA tools. Google "pt_shell tcl" or "ncsim tcl" for examples. Cadence and Mentor Graphic's digital simulation GUIs were built with Tk. Probably a lot more. The big win for Tk in GUIs in the late 90's was it's cross platform support. For all of its limitations - Tk was a huge improvement over Motif! Tcl is also used as a data file format for describing desing rules. Synopsys' SDC (standard design constraints) and Cadence's CPF (common power format) are both just design specific variations of Tcl. Writing a parser for these formats just requires writing command implementations. Tcl takes care of the rest.