regex's come up often here. Read the various nodes, even the ones where the titles look completely outside any area you think you may be interested in, because many threads wander all over the place and provide a lot if interesting, educational and thought provoking ideas.
You should browse the following documentation, probably in the order given: perlretut, perlre and perlreref.
In reply to Re^2: Directory Parsing
by GrandFather
in thread Directory Parsing
by Anonymous Monk
| For: | Use: | ||
| & | & | ||
| < | < | ||
| > | > | ||
| [ | [ | ||
| ] | ] |