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

[ron minnich]

On Tue, Jun 25, 2019 at 5:46 PM Larry McVoy <lm at mcvoy.com> wrote:
>
> I'm curious what Rob and others think of the Linux /proc.  It's string
> based and it seems like it is more like /whatever_you_might_want.

it's very handy but quite difficult to work with programatically. The
output is convenient for humans to parse, not very nice for programs
to parse.

/proc on linux has no real standard way of outputting things. You get
tables, tuples, and lists and some stuff I can't classify
(/proc/execdomains, /proc/devices); and, in some cases, some files
give you more than one type of thing. Units are not clear for many
tables.

/proc on linux has far more than just process information, including
stuff that has nothing to do with processes (51 things on my current
linux, e.g. /proc/mounts).

Things are in many cases not self-describing, though lots of /proc
have this issue.

I do recall (possibly wrongly) at some point in the 2000s there was an
effort to stop putting stuff in /proc, but rather in /sys, but that
seems to have not worked out. /proc is just too convenient a place,
and by convention, lots of stuff lands there.

While I was at LANL we did experiment with having /proc come out as
s-expressions, which were nicely self describing, composable, easily
parsed and operated on, and almost universally disliked b/c humans
don't read s-expressions that easily. So that ended.

We've been reimplementing Unix commands in Go for about 8 years now
and dealing with all the variance in /proc on linux was a headache.
You pretty much need a different function for every file in /proc.

And all that said, it's handy, so hard to complain about too much.