An Acronym for Stream EDitor
A very simple ProgrammingLanguage geared towards text manipulation for files larger than the avaliable RAM. SED scripts are very hard to read if they try to do anything even moderatly complex; you're better of using AWK or Perl in such cases. The latter has copied many concepts from both of the former languages.
See also:
A very nice sed tutorial at the GrymoireHe SED, She SED an issue of Shell Corner in the Unix ReviewHandy one-liners for sedsed resourcesseder's grab bag, a collection of sed scripts and miscellanyCategoryProgrammingLanguages, CategorySpecialPurposeProgrammingLanguages
5 pages link to SED:
lib/main.php:944: Notice: PageInfo: Cannot find action page