run os comand and write to a file code example

Example 1: python run command and read output

#!/usr/bin/python
import subprocess, sys
## command to run - tcp only ##
cmd = "/usr/sbin/netstat -p tcp -f inet"
## run it ##
p = subprocess.Popen(cmd, shell=True, stderr=subprocess.PIPE)
## But do not wait till netstat finish, start displaying output immediately ##
while True:
    out = p.stderr.read(1)
    if out == '' and p.poll() != None:
        break
    if out != '':
        sys.stdout.write(out)
        sys.stdout.flush()

Example 2: python run command and read output

>>> subprocess.check_output(['ls', '-l'])
b'total 0\n-rw-r--r--  1 memyself  staff  0 Mar 14 11:04 files\n'