What you describe happened far earlier. As far as I understand it, regexps were originally a part of ed (having been derived from QED), the original Unix text editor. Its “g” command with a “p” flag, or “g/re/p”, for globally searching for a regexp and printing the matching lines, was later found so useful that it was implemented into a separate utility, “grep”. Many Unix utilities started using regular expressions from then on, including Perl.