outlet - an opening that permits escape or release; he blocked the way out; the canyon had only one issue. exit, way out, issue. opening - a vacant or unobstructed space that is man-made; they left a small opening for the cat at the bottom of the door.
Differences between grep, pgrep, egrep, and fgrep (Linux): grep grep is an acronym that stands for Global Regular Expressions Print. grep is a program which scans a specified file or files line by line, returning lines that contain a pattern. A pattern is an expression that specifies a set of strings by interpreting characters as meta-characters.
History of sed [edit]. First appearing in Version 7 Unix, sed is one of the early Unix commands built for command line processing of data files. It evolved as the natural successor to the popular grep command. The original motivation was an analog of grep (g/re/p) for substitution, hence g/re/s.