Florian Bruhin <me@the-compiler.org> writes:
* Nikolaus Rath <Nikolaus@rath.org> [2014-06-12 19:11:07 -0700]:
"R. David Murray" <rdmurray@bitdance.com> writes:
Also notice that using a list with shell=True is using the API incorrectly. It wouldn't even work on Linux, so that torpedoes the cross-platform concern already :)
This kind of confusion is why I opened http://bugs.python.org/issue7839.
Can someone describe an use case where shell=True actually makes sense at all?
It seems to me that whenever you need a shell, the argument's that you pass to it will be shell specific. So instead of e.g.
Popen('for i in `seq 42`; do echo $i; done', shell=True)
you almost certainly want to do
Popen(['/bin/sh', 'for i in `seq 42`; do echo $i; done'], shell=False)
because if your shell happens to be tcsh or cmd.exe, things are going to break.
My usecase is a spawn-command in a GUI application, which the user can use to spawn an executable. I want the user to be able to use the usual shell features from there. However, I also pass an argument to that command, and that should be escaped.
You should pass the command as a string and use cmd.exe quote rules [1] (note: they are different from the one provided by `subprocess.list2cmdline()` [2] that follows Microsoft C/C++ startup code rules [3] e.g., `^` is not special unlike in cmd.exe case). [1]: http://blogs.msdn.com/b/twistylittlepassagesallalike/archive/2011/04/23/ever... [2]: https://docs.python.org/3.4/library/subprocess.html#converting-an-argument-s... [3]: http://msdn.microsoft.com/en-us/library/17w5ykft%28v=vs.85%29.aspx -- akira