is used by scripts for the latex-papersize, ebong and lilyglyphs CTAN modules, these will not work with python3 and are unmaintained. In pythontex there are scripts to invoke python3 or python2 according to the system's version of python. is used by two scripts, one is for pTex (Japanese vertical writing) and the other is match_parens which might be generally useful. The perl module Tk, which needs to be run from an X11 session to run the tests and requires is used by one of the scripts for ptex and is needed for texdoctk (a GUI interface for finding documentation files and opening them with the appropriate viewer). ps2pdf, from , is used by some utilities and scripts.