The "S" (substitute) editor command is old enough for a CoVid jab: Deutsch, L. Peter; Lampson, Butler W. (1967), "An online editor", Communications of the ACM, 10 (12) (page 16). It got lower-cased when Ken Thompson and Dennis Ritchie created the UI for ed in the new Unix OS a few years later. We walk in the footsteps of giants. Your personal computing device (as envisaged by Lampson) runs an OS inspired more (Linux, iOS, OSX, Android) or less (Windows) directly by Unix and, especially in the former case, probably depends on Deutsch's GhostScript interpreter for printing and PDF creation.Yes, I figured that out once I'd woken up. I'm not a Linux person but the 's/this/that' construction has been used on Cix for as long as I can remember to correct a posting.
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