cpython/Doc/library/commands.rst

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:mod:`commands` --- Utilities for running commands
==================================================
.. module:: commands
:platform: Unix
:synopsis: Utility functions for running external commands.
.. sectionauthor:: Sue Williams <sbw@provis.com>
The :mod:`commands` module contains wrapper functions for :func:`os.popen` which
take a system command as a string and return any output generated by the command
and, optionally, the exit status.
The :mod:`subprocess` module provides more powerful facilities for spawning new
processes and retrieving their results. Using the :mod:`subprocess` module is
preferable to using the :mod:`commands` module.
.. note::
In Python 3.x, :func:`getstatus` and two undocumented functions
(:func:`mk2arg` and :func:`mkarg`) have been removed. Also,
:func:`getstatusoutput` and :func:`getoutput` have been moved to the
:mod:`subprocess` module.
The :mod:`commands` module defines the following functions:
.. function:: getstatusoutput(cmd)
Execute the string *cmd* in a shell with :func:`os.popen` and return a 2-tuple
``(status, output)``. *cmd* is actually run as ``{ cmd ; } 2>&1``, so that the
returned output will contain output or error messages. A trailing newline is
stripped from the output. The exit status for the command can be interpreted
according to the rules for the C function :cfunc:`wait`.
.. function:: getoutput(cmd)
Like :func:`getstatusoutput`, except the exit status is ignored and the return
value is a string containing the command's output.
.. function:: getstatus(file)
Return the output of ``ls -ld file`` as a string. This function uses the
:func:`getoutput` function, and properly escapes backslashes and dollar signs in
the argument.
.. deprecated:: 2.6
This function is nonobvious and useless. The name is also misleading in the
presence of :func:`getstatusoutput`.
Example::
>>> import commands
>>> commands.getstatusoutput('ls /bin/ls')
(0, '/bin/ls')
>>> commands.getstatusoutput('cat /bin/junk')
(256, 'cat: /bin/junk: No such file or directory')
>>> commands.getstatusoutput('/bin/junk')
(256, 'sh: /bin/junk: not found')
>>> commands.getoutput('ls /bin/ls')
'/bin/ls'
>>> commands.getstatus('/bin/ls')
'-rwxr-xr-x 1 root 13352 Oct 14 1994 /bin/ls'
.. seealso::
Module :mod:`subprocess`
Module for spawning and managing subprocesses.