I just finished writing my third e-book about Perl one-liners. Perl one-liners are small and awesome Perl programs that fit in a single line of code and they do one thing really well. These things include changing line spacing, numbering lines, doing calculations, converting and substituting text, deleting and printing certain lines, parsing logs, editing files in-place, and many more. The book is 111 pages long and contains precisely 130 well explained one-liners. Have a look!