How to check if a user exists in a GNU/Linux OS using Python?

Question

What is the easiest way to check the existence of a user on a GNU/Linux OS, using Python?

Anything better than issuing ls ~login-name and checking the exit code?

And if running under Windows?

Answer 1

This answer builds upon the answer by Brian. It adds the necessary try...except block.

Check if a user exists:

import pwd

try:
    pwd.getpwnam('someusr')
except KeyError:
    print('User someusr does not exist.')

Check if a group exists:

import grp

try:
    grp.getgrnam('somegrp')
except KeyError:
    print('Group somegrp does not exist.')