Python Script execute commands in Terminal

import os

os.system("ls -l")

import subprocess
test = subprocess.Popen(["ping","-W","2","-c", "1", "192.168.1.70"], stdout=subprocess.PIPE)

I prefer usage of subprocess module:
from subprocess import call
call(["ls", "-l"])

Reason is that if you want to pass some variable in the script this gives very easy way for example take the following part of the code
abc = a.c
call(["vim", abc])