perl regex - pattern matching

Question

Can anyone explain what is being done below?

 $name=~m,common/([^/]+)/run.*/([^/]+)/([^/]+)$,;

Answer 1

• common, run and / are match themselves.
• () captures.
• [^/]+ matches 1 or more characters that aren't /.
• .* matches 0 or more characters that aren't Line Feeds.^[1]
• $ is equivalent to (\n?\z).^[2]
• \n optionally matches a Line Feed.
• \z matches the end of the string.

I think it's trying to match a path of one or both of the following forms:

• .../common/XXX/runYYY/XXX/XXX
• common/XXX/runYYY/XXX/XXX

Where

• XXX is a sequence of at least one character that doesn't contain /.
• YYY is a sequence of any number of characters (incl zero) that doesn't contain /.

It matches more than that, however.

• It matches uncommon/XXX/runYYY/XXX/XXX
• It matches common/XXX/runYYY/XXX/XXX/XXX/XXX/XXX/XXX

The parts in bold are captured (available to the caller).

---

1. When the s flag isn't used.
2. When the m flag isn't used.