One of the things that makes UNIX very powerful is the way that patterns can be used to specify what you are looking for in a general way. You saw this with filename generation wildcards, which enable you to form a list of files based on a pattern. In this section, you will meet a totally different form of UNIX wildcard that I call a regular expression wildcard. UNIX neophytes often confuse filename generation wildcards with regular expression wildcards and then wonder why things do not work as they expect.
Where Does grep Get Its Name?
The text editor ed was commonly used before vi was available. In the ed editor, g/re/p is a command used to globally search for the regular expression ...