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

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

Anything better than issuing开发者_开发知识库 ls ~login-name and checking the exit code?

And if running under Windows?

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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.') 

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To look up my userid (bagnew) under Unix:

import pwd
pw = pwd.getpwnam("bagnew")
uid = pw.pw_uid

See the pwd module info for more.

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Using pwd you can get a listing of all available user entries using pwd.getpwall(). This can work if you do not like try:/except: blocks.

import pwd

username = "zomobiba"
usernames = [x[0] for x in pwd.getpwall()]
if username in usernames:
    print("Yay")

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I would parse /etc/passwd for the username in question. Users may not necessarily have homedir's.

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Similar to this answer, I would do this:

>>> import pwd
>>> 'tshepang' in [entry.pw_name for entry in pwd.getpwall()]
True