grep very often, and I made-up and acronym that made sense to me: Get REgular ExPression
But I discovered this YouTube video that gives an accurate historical recounting of its birth and where its name came from. See video below, titled “Where GREP Came From – Computerphile”
Summary: this comes from the command
gfind regular expression
p. The command comes from the old text editor “ed”, a one-line-at-a-time editor, more or less and ancestor of “vi”/”vim”.
As it happens when I was a graduate student I created my first, 20 pages report using “ed” but I was far from knowing about regular expressions then. So I enjoyed watching Professor Brian Kernighan explaining “ed” in the first part of the video, and how, overnight,
grep was born, written by Ken Thompson.
(See also Wikipedia entry for Grep for more info about variants, versions etc.)
If you are interested in the origin of things, the following 10min video is a cool watch!