d to delete the pattern space, q to quit, N to add the next line to the pattern space immediately, and so on. Other end-of-script behaviors are available through sed options and script commands, e.g. For each input line, after running the script, sed ordinarily outputs the pattern space (the line as modified by the script) and begins the cycle again with the next line. sed implements a programming language with about 25 commands that specify the operations on the text. To the pattern space, sed applies one or more operations which have been specified via a sed script. Sed is a line-oriented text processing utility: it reads text, line by line, from an input stream or file, into an internal buffer called the pattern space. It is used on embedded systems and is the version of sed provided with Minix. Its advantage is that it is very fast and uses little memory. The current minised contains some extensions to BSD sed but is not as feature-rich as GNU sed. minised was used by the GNU Project until the GNU Project wrote a new version of sed based on the new GNU regular expression library. Raymond and currently maintained by René Rebe. Another variant of sed is minised, originally reverse-engineered from 4.1BSD sed by Eric S.
Super-sed is an extended version of sed that includes regular expressions compatible with Perl. GNU sed added several new features, including in-place editing of files. sed and AWK are often cited as progenitors and inspiration for Perl, and influenced Perl's syntax and semantics, notably in the matching and substitution operators. Later, the more powerful language AWK developed, and these functioned as cousins, allowing powerful text processing to be done by shell scripts. The syntax for sed, notably the use of / for pattern matching, and s/// for substitution, originated with ed, the precursor to sed, which was in common use at the time, and the regular expression syntax has influenced other languages, notably ECMAScript and Perl. Foreseeing that further special-purpose programs for each command would also arise, such as g/re/d, McMahon wrote a general-purpose line-oriented stream editor, which became sed. The original motivation was an analogue of grep (g/re/p) for substitution, hence "g/re/s". It evolved as the natural successor to the popular grep command.
First appearing in Version 7 Unix, sed is one of the early Unix commands built for command line processing of data files.
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