This is a version of sed based on GNU sed. It is not a version of GNU sed, though. There are several new features (including in-place editing of files, extended regular expression syntax and a few new commands) and some bug fixes; see the NEWS file for a brief summary and the ChangeLog for more detailed descriptions of changes. The biggest note, i think is the *huge* speed difference, where regular sed might take a few mins, super-sed can take only seconds this is not true in all cases, and sometimes you have modify your regexp syntax, however for the speed increase, it might be worth it. WWW: http://sed.sourceforge.net/grabbag/ssed/