system in Python

system.py

import os
import sys

def my_system(command):
    pid = os.fork()

    if pid == -1:
        return -1
    elif pid == 0:
        os.execv('/bin/sh', ['/bin/sh', '-c', command])
        sys.exit(-1) # in case execv failed

    _, st = os.waitpid(pid, 0)
    return st

if __name__ == '__main__':
    print my_system('ls -lh')
    print my_system('python -c "import this"')
    print my_system('dontexist')