Good beginners regex info try Perlmonks Tutorial: Regular Expressions Tutorial, the Basics (for BEGINNERS)
I have also found http://www.regular-expressions.info/quickstart.html very helpful working with regex's. Lots of good examples.
I found tools like http://www.txt2re.com/ or Eclipses regex tool to be helpful in debugging my regex commands.
Before posting questions try searches on Perlmonks and playing around with some code using the tools I just listed, you'll get more help with examples.
Good Luck.
-- Grey Fox
"We are grey. We stand between the darkness and the light" B5

In reply to Re: Extract a string by Grey Fox
in thread Extract a string by scarus

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