Function for running a given command with, or without pipes.

pipe.py

from subprocess import Popen
from subprocess import PIPE

# def run(command):
#     '''Run the given command and return its output
#     and exit_code'''
# setting parameter shell=True does the same thing, but, security matters
#     process = Popen(command.split(), stdout=PIPE, shell=True)
#     (output, _status) = process.communicate()
#     exit_code = process.wait()
#     return output, exit_code

def run(command):
    '''Run the given command and return its output
    and exit_code'''
    # for some reason there is a problem if there are double or single quotes in command
    command = command.replace('"', '')
    command = command.replace("'", "")
    if "|" in command:
        command_parts = command.split("|")
    else:
        command_parts = []
        command_parts.append(command)
    i = 0
    pipe = {}
    for command_part in command_parts:
        if i == 0:
            pipe[i] = Popen(command_part.split(), stdout=PIPE)
        else:
            pipe[i] = Popen(command_part.split(), stdin=pipe[i-1].stdout, stdout=PIPE)
        i = i + 1
    (output, _status) = pipe[i-1].communicate()
    exit_code = pipe[i-1].wait()
    return output, exit_code

# com = 'ls'
# com = 'ls -a'
# com = 'fortune | cowsay'
com = 'ls /dev | grep "ttyS2" | grep "ttyS20"'
# com = "ls /dev | grep 'ttyS2' | grep 'ttyS20'"

print run(com)[0]