[Python-Dev] subprocess shell=True on Windows doesn't escape ^ character

[Florian Bruhin]

* anatoly techtonik <techtonik at gmail.com> [2014-06-12 02:00:55 +0300]:
> On Thu, Jun 12, 2014 at 1:30 AM, Chris Angelico <rosuav at gmail.com> wrote:
> 
> > Why pass shell=True when executing a single
> > command? I don't get it.
> >
> 
> I don't know about Linux, but on Windows programs are not directly
> available as /usr/bin/python, so you need to find command in PATH
> directories. Passing shell=True makes this lookup done by shell and not
> manually.

As it's been said, the whole *point* of shell=True is to be able to
use shell features, so ^ being escaped automatically just would be...
broken. How would I escape > then, for example ;)

You basically have two options:

- Do the lookup in PATH yourself, it's not like that's rocket science.

  I haven't checked if there's a ready function for it in the stdlib,
  but even when not: Get os.environ['PATH'], split it by os.pathsep,
  then for every directory check if your binary is in there. There's
  also some environment variable on Windows which contains the
  possible extensions for a binary in PATH, add that, and that's all.

- Use shell=True and a cross-platform shell escape function. I've
  wrote one for a project of mine: [1]

  I've written some tests[2] but I haven't checked all corner-cases,
  so I can't guarantee it'll always work, as the interpretation of
  special chars by cmd.exe *is* black magic, at least to me.

  Needless to say this is probably the worse choice of the two.

  [1] http://git.the-compiler.org/qutebrowser/tree/qutebrowser/utils/misc.py?id=dffec73db76c867d261ec3416de011becb209f13#n154
  [2] http://git.the-compiler.org/qutebrowser/tree/qutebrowser/test/utils/test_misc.py?id=dffec73db76c867d261ec3416de011becb209f13#n195

Florian

-- 
http://www.the-compiler.org | me at the-compiler.org (Mail/XMPP)
             GPG 0xFD55A072 | http://the-compiler.org/pubkey.asc
         I love long mails! | http://email.is-not-s.ms/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 836 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/python-dev/attachments/20140612/a6a9dd2c/attachment.sig>