[9fans] recreational programming of an evening

[ron minnich <rminnich@gmail.com>]

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I wanted /proc/<pid>/truss to be more infomative ... and I wanted to
trace things that fork/exec. I can now see things like file names, IO
data, and so on. This is only in 9vx at present.

For RFORK, the output from /proc/<pid>/truss is just Rfork unless it
is creating new proc, in which case it is ProcRfork. That's how the rc
script knows to start a new truss.

So here is the result: very minor extension to the kernel code, shell
script a bit longer (25 lines!) but what happens is e.g. you trace an
rc, and for each fork/exec that happens, a new truss display pops up
in a new window and you can now watch the kid. And yes it does work
fine if the thing you start is an rc.

Watching ssh is fun. I hope to use this to try to find out what hg is up to.

Screen shot attached, this is pretty handy for me and if you want my
patch to 9vx let me know. What's interesting to me about this is that
I can not imagine even attempting this on any other os or windowing
system. It was just too easy on Plan 9 however.

ron

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