Python function that calls bash commands

Question

I am trying to make a Python function that will take a bash command (cmd) as an argument, and then execute that command.

But I am having some issues...

This is my program:

import subprocess

def main():
    runCommand("ls")
    runCommand("ls -l")
    runCommand("cd /")
    runCommand("ls -l")

def runCommand(cmd):
    subprocess.Popen(cmd)

It works for commands like "ls" or "who" but when it gets longer such as "ls -l" or "cd /" it gives me an error.

Traceback (most recent call last):
  File "<string>", line 1, in ?
  File "test.py", line 8, in main
    runCommand("ls -l")
  File "test.py", line 14, in runCommand
    subprocess.Popen(cmd)
  File "/usr/lib64/python2.4/subprocess.py", line 550, in __init__
    errread, errwrite)
  File "/usr/lib64/python2.4/subprocess.py", line 996, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

Kasravnd · Accepted Answer · 2014-10-11 17:01:28Z

1

You need to put your command and its option in a list :

subprocess.Popen(['ls','-l'])

answered Oct 11, 2014 at 17:01

Kasravnd

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5 Comments

jean Over a year ago

yes that works, but would you happen to know why (['cd', '/']) gives me a error of: "No such file or directory" ?

Kasravnd Over a year ago

you need to use subprocess.Popen(['cd','/'],shell=True) for that ! but for change directory a better way is using os.chdir

user1277476 Over a year ago

subprocess.Popen(['ls','-l']) works fine for me. No need for shell=True here.

user1277476 Over a year ago

Each subprocess.Popen will start a distinct shell that doesn't live very long. So when you "cd /", and the shell exits, your cd / is lost in the next shell. So if you need to cd around, you'd probably better use something like shell=True and ['cd / && ls -l'].

Kasravnd Over a year ago

yes you are right ,so as i dont knew actually what you want to do with cd / so i just give a common proposition !;)

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