#!/usr/bin/perl -w

#Plugin created by:
# Stephen Hodgson
# Malone College - CPSC
# ported to perl and extended by Thomas Gutzler, 2008 (thomas.gutzler@gmail.com)

# Feel free to modify this plugin, but if you do, be kind and email it back to me.  I'm all for improvements that anyone can make.

# - This simple plugin figures out how many users are logged into the linux box
# - The plugin takes advantage of the linux 'who' command.
# - The who command is used to list all login names and number of users logged on.
# - This information is used to output to values:
#   1. total amount of users logged in
#   2. amount of unique users logged in

# Even though this plugin should run without configuration, it is possible to tell it the location of the who command
# Configuration example
# [usersv2]
# env.who_cmd /usr/bin/who

#%# family=auto
#%# capabilities=autoconf

use strict;

my $who_cmd = exists $ENV{who_cmd} ? $ENV{who_cmd} : 'who';

if ((exists $ARGV[0]) && ($ARGV[0] eq "autoconf")) {
	my @who = ("$who_cmd -q >/dev/null 2>&1");
	my $ret = system(@who);
	if ($ret == 0) {
		print "yes\n";
		exit 0;
	} else {
		print "no\n";
		exit 1;
	}
}

if ((exists $ARGV[0]) && ($ARGV[0] eq "config")) {
	print "graph_title Users Online\n";
	print "graph_args --base 1000 -l 0\n";
	print "graph_scale no\n";
	print "graph_vlabel Number of users\n";
	print "graph_category system\n";
	print "graph_info This graph shows the amount of (unique) users logged in\n";
	print "users.label total users\n";
	print "users.info something like who | wc -l\n";
	print "uusers.label unique users\n";
	print "uusers.info something like who | cut -f -1 -d ' ' | sort | uniq | wc -l\n";
	exit 0;
}

my @who = split(/\s+/, `$who_cmd -q | head -1`);
print "users.value ".scalar(@who)."\n";

my %who;
$who{$_} = 1 foreach (@who);
print "uusers.value ".scalar(keys %who)."\n";