There is this nifty feature in Unix-based systems called “regex”, which is an abbreviation of the world “Regular Expressions” (here is a Wikipedia article on it).
Basically, it is “a string that describes or matches a set of strings, according to certain syntax rules”.
Regex had always been one of my weaknesses, but hopefully I’ll be cured of it soon, as I’ve found a very good guide here (Mozilla Developer Center).
Now, if I can just get over my laziness and take the time to read through it…
Update: I’ve just found another fantastic resource, this time an entire site dedicated to RegEx!