I remember using TECO briefly on a VMS system waybackwhen (I very soon switched to EVE as apparently it was “better”). Can’t remember a thing about it, and I certainly never used any of the advanced functionality (boy was I glad to discover the VMS POSIX subsystem some time later!).
If, by chance, you've ever heard of a little editor
called "emacs"; well, that was originally a set of
editor macros for TECO (EMACS = Editor MACroS).
Also, I like the link he provides at the bottom: http://almy.us/teco.html
I remember in, in the 90s, reading an introduction to TECO, which was already ancient and disused… and realizing that the intro I was reading had been written by a local newspaper, ten years earlier.
It was really neat to realize that programmers aren’t the only ones who care a lot about text editors and have a reason to be early adopters.
My only experience with TECO is the “If you type your name into TECO and something cool happens, it’s a good omen” myth.
Nothing magical happened. 25 years later I’m still gainfully employed so meh, obviously the TECO oracle has its limitations :)