<?php
	
	/***  
	* Configuration:  
	*
	*	$CONFIG = array(
	*		'warning' => 2000000,	-> threshold free memory in kilobytes for status warning
	*		'critical' => 1000000	-> threshold free memory in kilobytes for status critical
	*	);
	*
	*/


	$CONFIG = array(
		'warning' => 2000000,
		'critical' => 1000000	
	);
	
	
	// execute command
	exec('free', $output);
	
	// get result
	if (preg_match('/^Mem:\s+([0-9]+)\s+([0-9]+)\s+([0-9]+)\s/U', $output[1], $result)) {
		$memory['total'] = $result[1];
		$memory['used'] = $result[2];
		$memory['free'] = $result[3];
	}

	// output result
	if ( $memory['free'] < $CONFIG['critical'] ) {
		echo 'FAILURE: '. $memory['free'] .' kilobytes free|performance:'. $memory['free'];
	}
	elseif ( $memory['free'] < $CONFIG['warning'] ) {
		echo 'WARNING: '. $memory['free'] .' kilobytes free|performance:'. $memory['free'];
	}
	else {
		echo 'OK: '. $memory['free'] .' kilobytes free|performance:'. $memory['free'];
	}
	
?>