New submission from David Fraser <dav...@sjsoft.com>:
(from
http://stackoverflow.com/questions/1253122/why-does-subprocess-popen-with-shelltrue-work-differently-on-linux-vs-windows/1254322)
When using subprocess.Popen(args, shell=True) to run "gcc --version"
(just as an example), on Windows we get this:
>>> from subprocess import Popen
>>> Popen(['gcc', '--version'], shell=True)
gcc (GCC) 3.4.5 (mingw-vista special r3) ...
So it's nicely printing out the version as I expect. But on Linux we get
this:
>>> from subprocess import Popen
>>> Popen(['gcc', '--version'], shell=True)
gcc: no input files
Because gcc hasn't received the --version option.
The docs don't specify exactly what should happen to the args under
Windows, but it does say, on Unix, "If args is a sequence, the first
item specifies the command string, and any additional items will be
treated as additional shell arguments." IMHO the Windows way is better,
because it allows you to treat Popen(arglist) calls the same as
Popen(arglist, shell=True) ones.
The strange implementation is actually the UNIX one, which does the
following (where each space separates a different argument):
/bin/sh -c gcc --version
It looks like the correct implementation (at least on Linux) would be:
/bin/sh -c "gcc --version" gcc --version
Since this would set the command string from the quoted parameters, and
pass the other parameters successfully.
>From the sh man page section for -c:
Read commands from the command_string operand instead of from the
standard input. Special parameter 0 will be set from the command_name
operand and the positional parameters ($1, $2, etc.) set from the
remaining argument operands.
This patch seems to fairly simply do the trick, as well as testing it.
----------
components: Library (Lib)
files: current-2.6.patch
keywords: patch
messages: 91492
nosy: davidfraser
severity: normal
status: open
title: subprocess doesn't pass arguments correctly on Linux when shell=True
type: behavior
versions: Python 2.6
Added file: http://bugs.python.org/file14697/current-2.6.patch
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<http://bugs.python.org/issue6689>
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