用php制作一个css文件

I have an css compiler written in PHP. This compiler ensures that all the css files will be minified.

Eventually it echo all the css code. But I don't want to echo the code but that he makes or update a existing css file with the css code that he compiled.

But how is this possible with PHP? Here is the compiler that I use.

$cssFiles = array(
   '',
);

$buffer = "";
foreach ($cssFiles as $cssFile) {
    $buffer .= file_get_contents($cssFile);
}

// Remove comments
$buffer = preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer);
// Remove space after colons
$buffer = str_replace(': ', ':', $buffer);
// Remove whitespace
$buffer = str_replace(array("
", "", "
", "\t", '  ', '    ', '    '), '', $buffer);
// Enable GZip encoding.
ob_start("ob_gzhandler");
// Enable caching
header('Cache-Control: public');
// Expire in one day
header('Expires: ' . gmdate('D, d M Y H:i:s', time() + 86400) . ' GMT');
// Set the correct MIME type, because Apache won't set it for us
header("Content-type: text/css");
// Write everything out
echo($buffer);

you can write the $buffer var in existing css file

$a = fopen("my_css_file_written_with_php.css", 'w');
fwrite($a, $p);
fclose($a);
chmod("my_css_file_written_with_php.css", 0644);