$re = '/(?<FirstShortcut>(?:(?:\w+\+){0,3})(?<FirstKey>\w+|.\d{0,2}))(?:,\s(?<SecondShortcut>(?:(?:\w+\+){0,3})(?<SecondKey>\w+|.\d{0,2})))?/mi';
$str = 'Shift+Ctrl+Alt+C, Ctrl+Shift+Alt+F1
Ctrl+PageDown
Ctrl+Home
A, B
Ctrl+F11, Ctrl+Home
Ctrl+,
F11
F1';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php