Eryk Sun added the comment:
In Unix, passing an args list with shell=True makes the first element the -c
command. The remaining elements are arguments for the shell itself, which makes
them $N variables. For example:
>>> subprocess.call(['echo $0, $1', 'spam', 'eggs'], shell=True)
spam, eggs
In Windows, subprocess.list2cmdline assumes VC++ rules for creating a command
line from a list. cmd's parsing rules are very different -- e.g. '^' is the
escape character, and double quotes also escape special characters, except not
'%'. (Shockingly there is no way to escape '%' on the cmd.exe command line --
only in batch files by doubling it. If you think '^' escapes it, you're wrong.
cmd looks for an environment variable containing the '^' character. By luck
it's usually not found.) cmd's parsing is convoluted, to say the least. Now
combine that with having to pass command lines for external programs in way
that they survive cmd's parsing without also breaking how the external program
parses its command line. This problem is intractable. Just use a string. For
anything complicated you may have to experiment a few times to figure out some
permutation that works. The best option is to not use the shell at all.
----------
nosy: +eryksun
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue30079>
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