[TUHS] 4.1c bsd ptrace man entry ("ptrace is unique and arcane")

Norman Wilson norman at oclsc.org
Wed Jun 26 05:33:22 AEST 2019


It's interesting that this comment about ptrace was written
as early as 1980.

Ron Minnich's reference to Plan 9 /proc misses the mark, though.
By the time Plan 9 was written, System V already had /proc; see

https://www.usenix.org/sites/default/files/usenix_winter91_faulkner.pdf

And as the authors say, the idea actually dates back to Tom Killian's
/proc in Research UNIX.  I don't know when Tom's code first went
live, but I first heard about it by seeing it in action on my first
visit to Bell Labs in early 1984, and it was described in public in
a talk at the Summer 1984 USENIX conference in Salt Lake City.
I cannot quickly find an online copy of the corresponding paper;
pointers appreciated.  (Is there at least an online index of BTL
CSTRs?  The big search engine run by the place that still has
some 1127 old-timers can't find that either.)

As for ptrace itself, I heartily agree that /proc made it obsolete.
So did everyone else in 1127 when I was there, but nobody wanted
to update adb and sdb, which were big messes inside.  So I did,
attempting a substantial internal makeover of adb to ease making
versions for different systems and even cross-versions, but just
a quick hack for sdb.

Once I'd done that and shipped the new adb and sdb binaries to
all our machines, I removed the ptrace call from the kernel.
It happened that in the Eighth (or was it Ninth by then? I'd
have to dig out notes to find out) Edition manual, ptrace(2)
was on two facing pages.  To celebrate, I glued said pages
together in the UNIX Room's copy of the manual.

Would it were so easy to take out the trash today.

Norman Wilson
Toronto ON


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