Is there a portable way to get the current username in Python?

Windows:

os.environ.get('USERNAME')

Linux:

os.environ.get('USER')

Both:

os.environ.get('USER', os.environ.get('USERNAME'))

Note that environment variables can be modified by the user, so this is a potential security vulnerability. With this method, an attacker can easily fake their username.

You can also use:

os.getlogin()

These might work. I don’t know how they behave when running as a service. They aren’t portable, but that’s what os.name and ifstatements are for.

win32api.GetUserName()

win32api.GetUserNameEx(...) 

See:
http://timgolden.me.uk/python/win32_how_do_i/get-the-owner-of-a-file.html

I wrote the plx module some time ago to get the user name in a portable way on Unix and Windows (among other things):
http://www.decalage.info/en/python/plx

Usage:

import plx

username = plx.get_username()

(it requires win32 extensions on Windows)

Combine os.getuid() with pwd.getpwuid():

import os
import pwd

def get_username():
    return pwd.getpwuid(os.getuid())[0]

See pwd docs for more details.

If you are needing this to get user’s home dir, below could be considered as portable (win32 and linux at least), part of a standard library.

>>> os.path.expanduser('~')
'C:\Documents and Settings\johnsmith'

Also you could parse such string to get only last path component (ie. user name).

See: os.path.expanduser

Combined pwd and getpass approach, based on other answers:

try:
  import pwd
except ImportError:
  import getpass
  pwd = None

def current_user():
  if pwd:
    return pwd.getpwuid(os.geteuid()).pw_name
  else:
    return getpass.getuser()

You can get the current username on Windows by going through the Windows API, although it’s a bit cumbersome to invoke via the ctypes FFI (GetCurrentProcess → OpenProcessToken → GetTokenInformation → LookupAccountSid).

I wrote a small module that can do this straight from Python, getuser.py. Usage:

import getuser
print(getuser.lookup_username())

It works on both Windows and *nix (the latter uses the pwd module as described in the other answers).

To me using os module looks the best for portability: Works best on both Linux and Windows.

import os

# Gives user's home directory
userhome = os.path.expanduser('~')          

print "User's home Dir: " + userhome

# Gives username by splitting path based on OS
print "username: " + os.path.split(userhome)[-1]           

Output:

Windows:

User’s home Dir: C:Usersmyuser

username: myuser

Linux:

User’s home Dir: /root

username: root

No need of installing any modules or extensions.

For UNIX, at least, this works…

import commands
username = commands.getoutput("echo $(whoami)")
print username

edit:
I just looked it up and this works on Windows and UNIX:

import commands
username = commands.getoutput("whoami")

On UNIX it returns your username, but on Windows, it returns your user’s group, slash, your username.

—

I.E.

UNIX returns: "username"

Windows returns: "domain/username"

—

It’s interesting, but probably not ideal unless you are doing something in the terminal anyway… in which case you would probably be using os.system to begin with. For example, a while ago I needed to add my user to a group, so I did (this is in Linux, mind you)

import os
os.system("sudo usermod -aG "group_name" $(whoami)")
print "You have been added to "group_name"! Please log out for this to take effect"

I feel like that is easier to read and you don’t have to import pwd or getpass.

I also feel like having "domain/user" could be helpful in certain applications in Windows.

Using only standard python libs:

from os import environ,getcwd
getUser = lambda: environ["USERNAME"] if "C:" in getcwd() else environ["USER"]
user = getUser()

Works on Windows (if you are on drive C), Mac or Linux

Alternatively, you could remove one line with an immediate invocation:

from os import environ,getcwd
user = (lambda: environ["USERNAME"] if "C:" in getcwd() else environ["USER"])()

psutil provides a portable way that doesn’t use environment variables like the getpass solution. It is less prone to security issues, and should probably be the accepted answer as of today.

import psutil

def get_username():
    return psutil.Process().username()

Under the hood, this combines the getpwuid based method for unix and the GetTokenInformation method for Windows.

None of the above worked in my case (scroll down to the actual solution).
The problem I’m getting with all solutions is the wrong username when running commands with sudo:

• psutil soulution:

$ python3
>>> import psutil
>>> psutil.Process().username()
'ubuntu' # OK!

$ sudo su
$ python3
>>> import psutil
>>> psutil.Process().username()
'root' # OK!

$ sudo python3
>>> import psutil
>>> psutil.Process().username()
'root' # WRONG, should be ubuntu!

• getpass solution:

$ python3
>>> import getpass
>>> getpass.getuser()
'ubuntu' # OK!

$ sudo su
$ python3
>>> import getpass
>>> getpass.getuser()
'root' # OK!

$ sudo python3
>>> import getpass
>>> getpass.getuser()
'root' # WRONG, should be ubuntu!

• pwd + os.getuid solution:

$ python3
>>> import os, pwd
>>> pwd.getpwuid( os.getuid() )[ 0 ]
'ubuntu' # OK!

$ sudo su
$ python3
>>> import os, pwd
>>> pwd.getpwuid( os.getuid() )[ 0 ]
'root' # OK!

$ sudo python3
>>> import getpass
>>> getpass.getuser()
'root' # WRONG, should be ubuntu!

• os.getlogin works a bit different, but still wrong:

$ python3
>>> import os
>>> os.getlogin()
'ubuntu' # OK!

$ sudo su
$ python3
>>> import os
>>> os.getlogin()
'ubuntu' # WRONG, should be root!


$ sudo python3
>>> import os
>>> os.getlogin()
'ubuntu' # OK!

• os.getenv gives the same results:

$ python3
>>> import os
>>> os.getenv('SUDO_USER', os.getenv('USER'))
'ubuntu' # OK!

$ sudo su
$ python3
>>> import os
>>> os.getenv('SUDO_USER', os.getenv('USER'))
'ubuntu' # WRONG, should be root!


$ sudo python3
>>> import os
>>> os.getenv('SUDO_USER', os.getenv('USER'))
'ubuntu' # OK!

Switching SUDO_USER and USER gives the wrong result in sudo python3 case.

Actual solution (non-portable)

Solution is a bit tricky and rely on the default root home directory location but works for all cases:

$ python3
>>> import os
>>> 'root' if os.path.expanduser('~') == '/root' else os.getenv('SUDO_USER', os.getenv('USER'))
'ubuntu' # OK!

$ sudo su
$ python3
>>> import os
>>> 'root' if os.path.expanduser('~') == '/root' else os.getenv('SUDO_USER', os.getenv('USER'))
'root' #  OK!

$ sudo python3
>>> import os
>>> 'root' if os.path.expanduser('~') == '/root' else os.getenv('SUDO_USER', os.getenv('USER'))
'ubuntu' # OK!

this works for me:

import os
os.cmd("whoami")
print (os.cmd("whoami"))