Validating Crontab Entries with PHP

Question

What is the best way to validate a crontab entry with PHP? Should I be using a regex, or an external library? I\'ve got a PHP script that adds/removes entries from a crontab

Answer 1

Use the pattern: /^((?:[1-9]?\d|\*)\s*(?:(?:[\/-][1-9]?\d)|(?:,[1-9]?\d)+)?\s*){5}$/

In PHP: