Find Data in File

I've looked on Google and through PHP.net but I can't seem to find what I'm looking for.
What I'm trying to do is open a file through HTTP, then PHP searchs the file and where it finds lets say for example
something * something else
Where it knows what to start looking for, and what to end looking for and it takes it all the in between and puts in in a variable.

So yeah, I can't figure how to do this.
Thanks.

Try: preg_match (www.php.net/preg_match) or preg_match_all (http://us2.php.net/manual/en/function.preg-match-all.php)