Ron
I never understood why sendmail needed it. [Actually I never really understand sendmail's need but that's another discussion and discussion I've had with Ertc over the years]. But shell escape were pretty typical, until Kulp's ^Z job control stuff and/or real window managers - it would have sucked not to have had them.
Off the top of my head:
- any editor (text or graphical)
- things that controlled the screen like more(1) would have wanted to support something like this
- programs that produced graphical output -- from *roff/tex and the like, to many/most of the CAD programs, or even Ghostscript I think. You might want to dump out and suck back in something processed from another program, and the 'pipeline' was not always the easy/right way to do that. Classic example of calling on the PS/EPS tools from inside of troff. This is why tools like xdvi and the like supported it.
- long-running games where you did not want to lose your session
- many things that supported remote job entry/execution - which was really common in the old days [hence UUCP, the PWB RJE tools, rsh and the like]. IICR there was a couple of versions of telnet/supdup that could do it.
Clem
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