running a command line containing Pipes and displaying result to STDOUT

Question

How would one call a shell command from Python which contains a pipe and capture the output?

Suppose the command was something like:

cat file.log |          


        

Answer 1

Simple function for run shell command with many pipes

Using

res, err = eval_shell_cmd('pacman -Qii | grep MODIFIED | grep -v UN | cut -f 2')

Function

import subprocess


def eval_shell_cmd(command, debug=False):
    """
    Eval shell command with pipes and return result
    :param command: Shell command
    :param debug: Debug flag
    :return: Result string
    """
    processes = command.split(' | ')

    if debug:
        print('Processes:', processes)

    for index, value in enumerate(processes):
        args = value.split(' ')

        if debug:
            print(index, args)

        if index == 0:
            p = subprocess.Popen(args, stdout=subprocess.PIPE)
        else:
            p = subprocess.Popen(args, stdin=p.stdout, stdout=subprocess.PIPE)

        if index == len(processes) - 1:
            result, error = p.communicate()
            return result.decode('utf-8'), error