diff options
Diffstat (limited to 'Lib/subprocess.py')
| -rw-r--r-- | Lib/subprocess.py | 71 |
1 files changed, 59 insertions, 12 deletions
diff --git a/Lib/subprocess.py b/Lib/subprocess.py index ac92185..b47ebb8 100644 --- a/Lib/subprocess.py +++ b/Lib/subprocess.py @@ -104,7 +104,7 @@ appearance of the main window and priority for the new process. (Windows only) -This module also defines four shortcut functions: +This module also defines some shortcut functions: call(*popenargs, **kwargs): Run command with arguments. Wait for command to complete, then @@ -151,6 +151,17 @@ getoutput(cmd): >>> subprocess.getoutput('ls /bin/ls') '/bin/ls' +check_output(*popenargs, **kwargs): + 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: + + output = subprocess.check_output(["ls", "-l", "/dev/null"]) + Exceptions ---------- @@ -166,8 +177,8 @@ should prepare for OSErrors. A ValueError will be raised if Popen is called with invalid arguments. -check_call() will raise CalledProcessError, if the called process -returns a non-zero return code. +check_call() and check_output() will raise CalledProcessError, if the +called process returns a non-zero return code. Security @@ -321,12 +332,15 @@ import signal # Exception classes used by this module. class CalledProcessError(Exception): - """This exception is raised when a process run by check_call() returns - a non-zero exit status. The exit status will be stored in the - returncode attribute.""" - def __init__(self, returncode, cmd): + """This exception is raised when a process run by check_call() or + check_output() returns a non-zero exit status. + The exit status will be stored in the returncode attribute; + check_output() will also store the output in the output attribute. + """ + def __init__(self, returncode, cmd, output=None): self.returncode = returncode self.cmd = cmd + self.output = output def __str__(self): return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode) @@ -364,7 +378,7 @@ else: import pickle __all__ = ["Popen", "PIPE", "STDOUT", "call", "check_call", "getstatusoutput", - "getoutput", "CalledProcessError"] + "getoutput", "check_output", "CalledProcessError"] try: MAXFD = os.sysconf("SC_OPEN_MAX") @@ -410,12 +424,45 @@ def check_call(*popenargs, **kwargs): check_call(["ls", "-l"]) """ retcode = call(*popenargs, **kwargs) - cmd = kwargs.get("args") - if cmd is None: - cmd = popenargs[0] if retcode: + cmd = kwargs.get("args") + if cmd is None: + cmd = popenargs[0] raise CalledProcessError(retcode, cmd) - return retcode + return 0 + + +def check_output(*popenargs, **kwargs): + """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=subprocess.STDOUT. + + >>> check_output(["/bin/sh", "-c", + "ls -l non_existant_file ; exit 0"], + stderr=subprocess.STDOUT) + 'ls: non_existant_file: No such file or directory\n' + """ + if 'stdout' in kwargs: + raise ValueError('stdout argument not allowed, it will be overridden.') + process = Popen(*popenargs, stdout=PIPE, **kwargs) + output, unused_err = process.communicate() + retcode = process.poll() + if retcode: + cmd = kwargs.get("args") + if cmd is None: + cmd = popenargs[0] + raise CalledProcessError(retcode, cmd, output=output) + return output def list2cmdline(seq): |