/fd vs /proc

/fd vs /proc

[Scott]

Why doesn't /proc include information about open file descriptors for
each process?  I'm not asking for a new feature, mind you, just
wondering why it was done that way, since experience with unix has
shown that getting information about all the open files on the system
is very useful (see ofiles, lsof, etc).

One complication I can see is that this would make it possible for
processes owned by the right user or group to dup each other's
descriptors.  That's nice, because it gives you fd passing between
arbitrary processes, but without fine grained access control lists it's
hard to limit who can get your descriptors.

Linux, by the way, has really gone overboard with /proc.  You can get
all sorts of very useful information about all sorts of things out of
there.  It's nice, in a chaotic sort of way.