Unix::Login - Customizable Unix login prompt and validation
use Unix::Login; # This will return the same thing as getpwnam() on # success, or will die automatically on failure my @pw = login;
This is a simple yet flexible module that provides a Unix-esque login prompt w/ password validation. This is useful in custom applications that need to validate the username/password of the person using the app.
The above example is pretty much all you'll ever need (and all this module provides). Here are some specifics on the function provided:
This prompts for the username and password and tries to validate the login. On success, it returns the same thing that getpwuid() does: the username in a scalar context, or the passwd struct as an array in a list context. It returns undef on failure.
You can pass it an optional set of parameters. These will specify options for that login prompt only. The parameters and their default values are:
attempts Max login attempts  failmesg Print this on failure ["Login incorrect\n"] failsleep And sleep for this many seconds  failexit If can't login after (3) attempts, exit fatally  banner Banner printed once up top ["Please Login\n"] bannerfile File to print after banner (i.e. /etc/issue)  login Prompt asking for username ["login: "] password Prompt asking for password ["Password: "] sameuser Take username from process?  passreq Require a password for all users?  nohomemesg Printed if no homedir ["No home directory! Setting HOME=/\n"] stripspaces Strip spaces from username?  setenv If true, setup HOME and other %ENV variables  clearenv If true, first undef %ENV before setenv  path If setenv, set PATH to this for non-root [/usr/bin:] supath If setenv, set PATH to this for root [/usr/sbin:/usr/bin] maildir If setenv, set MAIL to this dir/username [/var/mail] input Where to read input from filehandle [STDIN] output Where to write output to filehandle [STDOUT] pwent Return a User::pwent struct in scalar context?  cdhome Chdir to the person's homedir on success?  execshell Execute the person's shell as login session? 
So, for example, you can create a fully-customized login screen like so:
use Unix::Login; my @pwent = login(login => "User: ", password => "Pass: ") || die "Sorry, try remembering your password next time.\n";
Often, you just want the user to re-enter their password, though. In this case, specify the
use Unix::Login; my @pwent = login(sameuser => 1);
login() will return true or die on exit, you can even just use it as a standalone line if you're just verifying their identity (and don't need the pw struct back). You may also want to turn off the banner for a better display:
login(sameuser => 1, banner => 0);
pwent option is set, then
User::pwent is used to provide an object in a scalar context:
use Unix::Login; my $pwent = login(pwent => 1);
See the man page for User::pwent for more details.
execshell option is set, then if login() is successful the user's shell is forked and the current process is terminated, just like a real Unix login session.
Thus, with these options, you could create a very Unix-like login:
use Unix::Login; my @pwent = login(bannerfile => '/etc/issue', banner => `uname -rs`, clearenv => 1, cdhome => 1, execshell => 1);
This will validate our login, clear our environment and reset it, then exec the shell as a login shell just like a real life Unix login.
If you really like OO-calling styles, this module also provides an OO form, although I personally think it's rather silly.
new() function creates a new Unix::Login object. It accepts the same parameters as listed above. Then, you call
login() as a member function. So for example:
use Unix::Login; my $ul = Unix::Login->new(setenv => 0, passreq => 0); my @pw = $ul->login;
Personally, I always just use
login() as a function...
This module automatically grabs control of the signals
QUIT, just like
DBI.pm, to make sure that a
^C causes the module to fail insted of accidentally succeed.
To use the
output options, you must first open the filehandle yourself, and then pass in a glob ref to the filehandle. For example:
# ... stuff to listen to SOCKET ... login(input => \*SOCKET, output => \*SOCKET);
These options are seldom used, so if this doesn't make any sense to you, don't sweat it.
Thanks to David Redmond to modernizing the
crypt() stuff so that it's RedHat-friendly.
$Id: Login.pm,v 1.8 2003/08/29 22:42:59 nwiger Exp $
User::pwent(3), login(1), perlfunc(1)
Copyright (c) 2000-2003 Nathan Wiger <email@example.com>. All Rights Reserved.
This module is free software; you may copy this under the terms of the GNU General Public License, or the Artistic License, copies of which should have accompanied your Perl kit.