magento-check.php

<?php

/**
 * A simple fix for a shell execution on preg_match('/[0-9]\.[0-9]+\.[0-9]+/', shell_exec('mysql -V'), $version);
 * The only edit that was done is that shell_exec('mysql -V') was changed to mysql_get_server_info() because not all
 * systems have shell access. XAMPP, WAMP, or any Windows system might not have this type of access. mysql_get_server_info()
 * is easier to use because it pulls the MySQL version from phpinfo() and is compatible with all Operating Systems.
 * @link http://www.magentocommerce.com/knowledge-base/entry/how-do-i-know-if-my-server-is-compatible-with-magento
 * @author Magento Inc.
 */

function extension_check($extensions) {
  $fail = '';
	$pass = '';
	
	if(version_compare(phpversion(), '5.2.0', '<')) {
		$fail .= '<li>You need<strong> PHP 5.2.0</strong> (or greater)</li>';
	} else {
		$pass .='<li>You have<strong> PHP 5.2.0</strong> (or greater)</li>';
	}

	if(!ini_get('safe_mode')) {
		$pass .='<li>Safe Mode is <strong>off</strong></li>';
		preg_match('/[0-9]\.[0-9]+\.[0-9]+/', mysql_get_server_info(), $version);
		
		if(version_compare($version[0], '4.1.20', '<')) {
			$fail .= '<li>You need<strong> MySQL 4.1.20</strong> (or greater)</li>';
		} else {
			$pass .='<li>You have<strong> MySQL 4.1.20</strong> (or greater)</li>';
		}
	} else { $fail .= '<li>Safe Mode is <strong>on</strong></li>';  }

	foreach($extensions as $extension) {
		if(!extension_loaded($extension)) {
			$fail .= '<li> You are missing the <strong>'.$extension.'</strong> extension</li>';
		} else{	$pass .= '<li>You have the <strong>'.$extension.'</strong> extension</li>';
		}
	}
	
	if($fail) {
		echo '<p><strong>Your server does not meet the following requirements in order to install Magento.</strong>';
		echo '<br>The following requirements failed, please contact your hosting provider in order to receive assistance with meeting the system requirements for Magento:';
		echo '<ul>'.$fail.'</ul></p>';
		echo 'The following requirements were successfully met:';
		echo '<ul>'.$pass.'</ul>';
	} else {
		echo '<p><strong>Congratulations!</strong> Your server meets the requirements for Magento.</p>';
		echo '<ul>'.$pass.'</ul>';

	}
}

extension_check(array( 
	'curl',
	'dom', 
	'gd', 
	'hash',
	'iconv',
	'mcrypt',
	'pcre', 
	'pdo', 
	'pdo_mysql', 
	'simplexml'
));

Line 65 add closing PHP tag
?>

Otherwise works great! Helped me figure out CURL and MCRYPT were not installed.

@eschrader Just don't add closing tags. People tend to add newlines after it unknowingly, which will result in that output being printed, and often in errors like "headers have already been sent". It's prone to errors, so it's advisable to skip it like author did here.

Awesome, thanks @atomicpages :)

I suggest adding the mbstring library in extension checking. We use it for Rest API.