CODEWITHSUNDEEP
pythonsubprocess
pythoner
pythoner

Reputation: 23

Why the subprocess.check_call commands always return 0?

I want to get path name from another .py file .

I called that .py file like 

xy=subprocess.check_call(["python","/home/emeks/workspace/ex/ex.py"])

print xy

but that print command always print zero ( 0 ) but I wanna get path name .

what should I do

Upvotes: 0

Views: 3374

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1122392

The purpose of subprocess.check_call() is to either return 0 or raise an exception if the exit status of the called process was not 0:

Run command with arguments. Wait for command to complete. If the return code was zero then return, otherwise raise CalledProcessError.

Use subprocess.check_output() instead if you need to read the output of the other command:

Run command with arguments and return its output as a byte string.

The function was added in Python 2.7; if you are using an earlier version of Python, here is a backport:

from subprocess import Popen, PIPE
from subprocess import CalledProcessError as BaseCalledProcessError

class CalledProcessError(BaseCalledProcessError):
    def __init__(self, returncode, cmd, output=None):
        super(CalledProcessError, self).__init__(returncode, cmd)
        self.output = output

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 = Popen(stdout=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 CalledProcessError(retcode, cmd, output=output)
    return output

Upvotes: 5

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