How do you grab username/login id in Unix?

jeremyw has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to figure out how to grab the username or login id on a unix/linux os. I figured out how to grab the username on a windows os (see the code below):

  # Grab username from PC:
  my $author= "$^O user";
  if ($^O =~ /mswin/i)
  { 
    $author= $ENV{USERNAME} if defined $ENV{USERNAME};
  }
  else
  { 
    $author = "$first $mid $last"; 
  }
[download]

I use the variable $author to print the username in a new file for documentation purposes. My perl script will be used on both Windows and Unix/Linux operating systems, so I'd like to include the ability to determine either. Any help is greatly appreciated.

Thanks,

Jeremy Webb

Comment on How do you grab username/login id in Unix? Download Code

Replies are listed 'Best First'.
Re: How do you grab username/login id in Unix? by Corion (Patriarch) on Dec 02, 2004 at 08:47 UTC
I just learned yesterday about the `getlogin` function built into Perl, which works under both, Unix and Windows: Implements the C library function of the same name, which on most systems returns the current login from /etc/utmp, if any. If null, use "getpwuid". `$login = getlogin \|\| getpwuid($<) \|\| "Kilroy";` [download] Do not consider "getlogin" for authentication: it is not as secure as "getpwuid". So the above code should be used instead of what you have now.	[reply] [d/l]
Re: How do you grab username/login id in Unix? by gaal (Parson) on Dec 02, 2004 at 04:58 UTC
`getpwuid($<)` will give you the uid of the user running the script. `getpwnam` from there will get you the login name and possibly the real name of the user.	[reply] [d/l] [select]
Re: How do you grab username/login id in Unix? by pearlie (Sexton) on Dec 02, 2004 at 05:17 UTC
Hello, you can also use my $user = `whoami`; [download] command to grab the user login name.	[reply] [d/l]
Re: How do you grab username/login id in Unix? by htoug (Deacon) on Dec 02, 2004 at 07:04 UTC
$ENV{LOGNAME} should do it in many cases. It has been defined as the username on all systems I have used. But the getpwxxx method that gaal showed is probably the best. It should work on more than just unix.	[reply]
about LOGNAME by Luca Benini (Scribe) on Dec 02, 2004 at 07:22 UTC
$ENV{LOGNAME} is setted at login time, so if someone log in as popeye and the do su his $ENV{LOGNAME} is again popeye. But if popoye do su - his $ENV{LOGNAME} is again popeye.	[reply]
Re: How do you grab username/login id in Unix? by Anonymous Monk on Dec 02, 2004 at 10:36 UTC
Hi Jeremy, Following command will give the username in windows and unix/linux getlogin() eg: my $username = getlogin(); print $username;	[reply]
Re^2: How do you grab username/login id in Unix? by jeremyw (Novice) on Dec 02, 2004 at 17:46 UTC
Thanks for everyone's help. It turned out for my case that the following worked the best for my application. `my $username = getlogin(); print $username;` [download] Thanks, Jeremy	[reply] [d/l]