WareLogging, sort of. Regular expressions are wonderful (and wonderfully ugly) little creatures used to describe patterns in text. Useful in good TextEditors, or in a language like PerlLanguage. This page is a repository of useful regex stuff.

= resources =

* LinuxInANutshell, 2nd edition
** p. 69, grep
** p. 247, pattern matching
** p. 208, perl quickref regex section

= WareLogging =

* PerlCompatibleRegularExpressions

= thoughts & recipes =

An EvolvingRegularExpression

Use egrep for complex expressions. Otherwise you will have to escape ?, +, {, |, (, and ) in order to get them to behave as special characters. If you're used to writing in Perl or similar, keep in mind that vi / VimEditor pattern matching will treat at least some of these characters as literals unless you escape them.

 (?<! ''regex'') ''other stuff''
 is a zero-width negative lookbehind assertion. Matches, in
 other words, if ''regex'' does *not* precede the ''other stuff''.

 egrep -ri "^[a-z., ]+$" ./*.dir
 Shows lines which are just alphanumeric plus period,
 comma, and space characters in all files with
 the extension .dir.

 tail -f /var/log/p1k3.access_log | egrep -vi "(googlebot|slurp)"
 following log file, wanted to avoid bot traffic noise
 may well eat CPU.