The following page explains "Famous Sed One-Liners", including the one you mention (it's #36, though you'll likely want to work your way down from the top): ht

The following page explains "Famous Sed One-Liners", including the one you mention (it's #36, though you'll likely want to work your way down from the top): http://www.catonmat.net/blog/sed-one-liners-explained-part-one/ http://www.catonmat.net/blog/sed-one-liners-explained-part-o... (CatOnMat.net is the site of one Peteris Krumins; he also has pages about AWK and Perl one-liners and he also has some other interesting stuff, e.g. he's gone through MIT's Introduction to Algorithms course videos and blogged each one, breaking the videos down by topics, with timestamps, as well as scans of his handwritten notes, etc.).