[python] How do you get the process ID of a program in Unix or Linux using Python?

For posix (Linux, BSD, etc... only need /proc directory to be mounted) it's easier to work with os files in /proc

Works on python 2 and 3 ( The only difference is the Exception tree, therefore the "except Exception", which i dislike but kept to maintain compatibility. Also could've created custom exception.)

#!/usr/bin/env python

import os
import sys


for dirname in os.listdir('/proc'):
    if dirname == 'curproc':
        continue

    try:
        with open('/proc/{}/cmdline'.format(dirname), mode='rb') as fd:
            content = fd.read().decode().split('\x00')
    except Exception:
        continue

    for i in sys.argv[1:]:
        if i in content[0]:
            # dirname is also the number of PID
            print('{0:<12} : {1}'.format(dirname, ' '.join(content)))

Sample Output (it works like pgrep):

phoemur ~/python $ ./pgrep.py bash
1487         : -bash 
1779         : /bin/bash