[TUHS] 8th Edition Research Unix on SIMH

Norman Wilson norman at oclsc.org
Thu Apr 27 11:04:37 AEST 2017


Tim Newsham:

  I'm not sure what fd 3 is intended to be, but its the telnet socket in p9p.

====

By the 10/e days, file descriptor 3 was /dev/tty.  There was
no more magic driver for /dev/tty; the special file still
existed, but it was a link to /dev/fd/3.

Similarly /dev/stdin stdout stderr were links to /dev/fd/0 1 2.

(I mean real links, not mere symbolic ones.)

I have a vague recollection that early on /dev/tty was fd/127
instead, but that changed somewhere in the middle 8/e era.

None of which says what Plan 9 did with that file descriptor,
though I suppose it could possibly have copied the /dev/tty
use.

And none of that excuses the hard-coded magic number file
descriptor, but hackers will be hackers.

Norman Wilson
Toronto ON


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