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Regular Expression Info and Tips for Powershell

One of the most useful tools a scripter has at their disposal is Regular Expressions. The problem is that regular expressions can seem like Greek and for most folks learning them can seem an impossible task. I hope this blog post provides those people some hope as well as some tools they can use to tackle this mountain one foot at a time.

NOTE: I would like to make this blog entry as dynamic as possible, so if you have your own tips… let me know and I will add them.


Everyone is different, but this is how I went about learning Regular Expressions

  • Phase one: Learn EXACTLY what a regular expression is and what it can and can NOT do.
  • Phase two: Learn the syntax. I printed out the RegEx Cheet Sheet and use it daily.
  • Phase three: Find a purpose. I find if I actually have a problem I spend more energy on learning.
  • Phase four: Create a simple Regular Expression.
  • Phase five: Build on your Regular Expression.
  • Phase six: Trouble shooting the Regular Expression.

Useful Tips:

  • First things first… Click here and watch the vids
  • Keep a cheat sheet close at hand!
  • Take them in small bites. I hope to blog in detail about this later, but lets just say string concatenation is your friend
  • Keep it simple!
  • $matches is your friend! $matches is an object that Powershell creates when you make a RegEx call (like -match.)
  • Google It. Chances are there is Regex already out there for what you need.
  • Using Lables can save you time by extracting certain data and making it a property on $matches.
  • RichardP from IRC says “Dont eat yellow snow?” Apparently he has experience in this area.

Online Vids:
This is GREAT stuff provided by Shay (aka scriptfanatic)

Good Blog Entries:
MoW at it again.

References:
RegEx Cheet Sheet (my Favorite)
Regular-Expressions.info
Regular Expression Library

Online Regex Checkers:
RegEx Tester (my Favorite)
Regular Expression Library Tester

Books:
Mastering Regular Expressions (my Favorite)
Regular Expression Recipes for Windows Developers

Tools:
Expresso
RegEx Buddy

One Response to “Regular Expression Info and Tips for Powershell”

  1. on 12 Jan 2009 at 10:20 amJason Archer

    I have also liked using Regex Coach:

    http://www.weitz.de/regex-coach/

    It is nice for checking if and when a regex is matching something. It is fast and easy to use (though no design mode).

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