<?php

	/***  
	* Configuration:  
	*
	*	$CONFIG = array(
	*		'warning' => 2,	-> number of logged in users as threshold for status warning
	*		'critical' => 4	-> number of logged in users as threshold for status critical
	*	);
	*
	*/

	
	$CONFIG = array(
		'warning' => 2,
		'critical' => 4
	);


	// exec command
	exec('uptime', $output);
	
	// get result
	if (preg_match('/,\s*([0-9]+)\suser/U', $output[0], $result)) {
		$users = $result[1];
	}

	// output result
	if ( $users > $CONFIG['critical'] ) {
		echo 'FAILURE: '. $users .' logged in|performance:'. $users;
	}
	elseif ( $users > $CONFIG['warning'] ) {
		echo 'WARNING: '. $users .' logged in|performance:'. $users;
	}
	else {
		echo 'OK: '. $users .' logged in|performance:'. $users;
	}
	
?>