PySh is a planned roughly POSIX-compliant shell with various built-ins to allow portability of the test suite. It is important that this tool be both simple and relatively self-contained.
Some useful links for getting started:
[http://pyparsing.wikispaces.com/ Pyparsing]: an easy-to-use recursive descent parser as a single Python module.
[http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_10 POSIX shell BNF]: a good starting point for building our shell grammar
[http://pyparsing.wikispaces.com/space/showimage/ebnf.py ebnf.py]: An EBNF->pyparsing converter
Other links:
[http://www.antlr.org Antlr]: An LL(k) recursive descent parser generator which can generate Python.
[http://www.dabeaz.com/ply PLY] - lex/yacc alike framework for Python
[http://dev.modelnine.org/hg/pyrr/ PyRR]: a lexing and parsing toolkit for Python.
[http://ipython.scipy.org/doc/manual/node12.html PySh]: the other Python shell
[http://www.busybox.net/cgi-bin/viewcvs.cgi/trunk/busybox/shell/ash.c Ash]: A maintained slim shell
[http://lists.samba.org/archive/linux/2004-February/009990.html Martin Pool presumes that it is not possible to use BNF to describe the sh grammar]
- - which is ok, because we only want to make a shell usable for the test suite, not a complete sh replacement