interesting you used grep because it's a command that has a very clear origin.

in ed/vi the g command was used to run commands on some pattern. eg g/[regex pattern]/[command]

the p command was used to print current line so to print any line that matched the string "grep" you would do: g/grep/p.

when this was made into a seperate command it was called grep: g/re/p. using re to denote regex.