I think ed also served the function of sed and patch. Ie you could record a bunch of edits into a file and it could read the script and perform all the edits to some input file. So it was more useful than an interactive line based editor sounds.

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layer8 a day ago | parent [-]

This is the same distinction as between running commands with bash -c (or just by executing a regular Bash script) and running them manually in an interactive Bash session. It’s pretty much an inherent feature of command-line interfaces that you can script them.

	▲	Brian_K_White 19 hours ago \| parent \| next [-]
		Wasn't intended to be a distinction but an aside. But as to that, it's slightly different than merely being able to play back a recording of commands. It IS that, but that can be applied in a way that acts more like the examples I said like sed or patch, or expect, where the script can apply some funcion to different inputs, not just playing back a recording. I'm not denying the implimentation, how the job gets done, is technically still just a recording of commands.
	▲	lern_too_spel 11 hours ago \| parent \| prev [-]
		It's different. Grep was a function of ed ('g/re/p') that was later extracted into its own program to search files that could not fit in memory. Sed then came along and implemented the 's/re/substitution/' functionality from ed for the streaming use case.