#regex

Don’t fear the regex! Learn regular expressions from the building blocks up: quantifiers, grouping, alternation, anchors, and greediness, plus tools and books.

Which batch jobs are still running? List files that lack a given line using grep -c, a regex anchor, and sed, then the one-flag fix: grep -L.

Scrape a command’s output in a few lines of Perl: load AIX vmstat values into a hash with a piped open and split, then with a one-line regex and reverse.

Now you have two problems. Why a regular expression is a poor substitute for a parser, shown by a unit-tested C# email validator built on a monster regex.