Expanding env variables

[gergelyk]

Hey, nice job with this utility :) Have you been considering processing args by os.path.expandvars, so that environment variables can be expanded?

[mwgamble]

I would like to see more customisation available with how commands are processed in general. Python3.6 added a new punctuation_chars option to the shlex class, which allows parsing of multiple commands in the following fashion: cmd1 arg1; cmd2 arg2. However, this module just calls shlex.split() directly with no opportunity to support punctuation_chars at all.