Get an overview of regex (regular expressions) and its associated terminology, with the links below.
There’s some information on how Textpression does things at the end of each tutorial, but the information in the tutorials themselves can be applied when using any regex tool, or just typing in Notepad/Vi/Editor of choice.
These tutorials won’t teach you everything you need to know about regex. They aren’t supposed to; there’s a ton of documentation out there already, which doesn’t need replicating! What they will do is give you the brief overview you need to quickly assess which regex functionality you need to get your current task job done. They’ll also give you the terminology that’ll let you efficiently Google for the features and syntax in your chosen regex flavor (.net, PHP etc).
What are regex? (what are they and how do you create one)
Alternation (matching a pattern of text from several alternatives)
Classes (matching a char from one or more specified chars)
Quantifers (specify how many times a pattern of text should be repeated in succession)
Anchors (matching text that starts and ends at certain positions)
Lookaround (Lookbehind and Lookahead are a step from anchors, you use a regex to specify where your match should start and end)
Much more coming soon!…