On Fri, 1 Jul 2022, Nelson H. F. Beebe wrote:
> Ctrl-D signifies end of transmission. Some other O/Ses have used
> Ctrl-Z for that purpose, presumably because Z is the final letter
> of numerous alphabets.
I thought only CP/M and its descendants did that. :o (Of course that
includes DOS and Windows)
Steve - The social disease spread of DOS-11, RT-11, CP/M, and MS/PS-DOS used ^Z as an EOF character in their text file format. The key is that they stored a block count, not a byte count in the META. Thus the last byte needs a marker to tell the OS to stop reading. [Early DEC OS's may have done that also, but I never looked at their FS formats].
Unix, of course, never made any distinction to the core OS WRT to 'type' [other than Regular/Directory/Special] and Ken stored a character count. So there was no need to signal EOF with a markered stored on disk..
A pipe or the shell on the other hand does have a need to signal the end of a transaction, and 'End of Transmission,' as Nelson points out, is the ASCII character reserved for the same.