http://docs.python.org/library/os.html#os.getuid
os.getuid() documentation just states:

> Return the current process’s user id.

It is not clear, however, whether "user id" refers to real, effective or saved user id.

As per:
http://linux.about.com/library/cmd/blcmdl2_getuid.htm
...it should refer to _real_ user id.

Update: I think also os.getlogin() doc is wrong.
This is what it states (2.7 doc):


> Return the name of the user logged in on the controlling terminal of 
> the process. For most purposes, it is more useful to use the 
> environment variable LOGNAME to find out who the user is, or 
> pwd.getpwuid(os.getuid())[0] to get the login name of the currently 
> effective user id.

Since os.getuid() refers to _real_ uid the last sentence should be changed as such:

- ... to get the login name of the currently effective user id.
+ ... to get the login name of the currently real user id.

These are wrappers around the posix functions.  As such the unix man pages are a better authority than the Python docs :)  Still, we could certainly improve the docs.

The getlogin error is probably a miscopy from the man page: the man page on my system shows the example as  getpwuid(geteuid()), but it is actually showing a replacement for 'cuserid', not 'getlogin'.

Indeed, now that I google for "getlogin", it's not easy to figure out what kind of user it is supposed to return exactly.

For getuid() it seems pretty clear that we're talking about _real_ uid, though.
http://www.manpagez.com/man/2/getuid/
http://linux.die.net/man/2/getuid