blob: e41a7f550607b4c946aa116a1e8c1f4d23e30aac [file] [log] [blame]
#!/usr/bin/env python
# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
# Backport of subprocess.check_output from python2.7
# Headers for that file are:
# subprocess - Subprocesses with accessible I/O streams
# For more information about this module, see PEP 324.
# This module should remain compatible with Python 2.2, see PEP 291.
# Copyright (c) 2003-2005 by Peter Astrand <>
# Licensed to PSF under a Contributor Agreement.
# See for licensing details.
import subprocess
import unittest
def check_output(*popenargs, **kwargs):
r"""Run command with arguments and return its output as a byte string.
If the exit code was non-zero it raises a CalledProcessError. The
CalledProcessError object will have the return code in the returncode
attribute and output in the output attribute.
The arguments are the same as for the Popen constructor. Example:
>>> check_output(["ls", "-l", "/dev/null"])
'crw-rw-rw- 1 root root 1, 3 Oct 18 2007 /dev/null\n'
The stdout argument is not allowed as it is used internally.
To capture standard error in the result, use stderr=STDOUT.
>>> check_output(["/bin/sh", "-c",
... "ls -l non_existent_file ; exit 0"],
... stderr=STDOUT)
'ls: non_existent_file: No such file or directory\n'
if 'stdout' in kwargs:
raise ValueError('stdout argument not allowed, it will be overridden.')
process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
output, unused_err = process.communicate()
retcode = process.poll()
if retcode:
cmd = kwargs.get("args")
if cmd is None:
cmd = popenargs[0]
raise subprocess.CalledProcessError(retcode, cmd)
return output
class CheckOutputTester(unittest.TestCase):
def test_check_output(self):
check_output, '/bin/false')
check_output, ['/bin/true'], stdout='/tmp/nonexistant')
check_output(['/bin/echo', 'hello']))
echoer = subprocess.Popen(['/bin/echo', 'hello'], stdout=subprocess.PIPE)
check_output(['/bin/cat'], stdin=echoer.stdout))
if __name__ == '__main__':