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

Answer 1

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

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

• jean: yes that works, but would you happen to know why (['cd', '/']) gives me a error of: "No such file or directory" ?
• Kasravnd: you need to use subprocess.Popen(['cd','/'],shell=True) for that ! but for change directory a better way is using os.chdir
• user1277476: subprocess.Popen(['ls','-l']) works fine for me. No need for shell=True here.
• user1277476: 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: yes you are right ,so as i dont knew actually what you want to do with cd / so i just give a common proposition !;)