I have had Regex Buddy for both windows and Linux for about 4/5 months now and I really don't know what I would do without it. Regex buddy makes it easy to build up regular expressions with the explanation for each step of the way. There is a section to allow you to test the expression and there is even a usage facility where you choose the language you need the regex for and the code is auto generated. The best thing is since I've been using it I've definitely learnt more about the black art of regex.