bash fdesc requirement?

[Lowell Gilbert]

Gary Aitken <freebsd at dreamchaser.org> writes:

> Building up a 9.3-release system.
> After doing a pkg upgrade I see this message:
>
> Message for bash-4.3.30_1:
>  ======================================================================
> bash requires fdescfs(5) mounted on /dev/fd
> If you have not done it yet, please do the following:
>         mount -t fdescfs fdesc /dev/fd
> To make it permanent, you need the following lines in /etc/fstab:
>         fdesc   /dev/fd         fdescfs         rw      0       0
>
> Yet it seems to run just fine without it.  (simple test, start bash and
> exit...)
>
> Can someone explain what's going on, and why one would or would not 
> add the indicated line to /etc/fstab?

It's for Process Substitution (described briefly in the manual). I don't
know why the maintainer noted it as "required" -- in fact, I can't think
of any functionality it enables that can't also be done with named
pipes. But the maintainer added the note fairly recently, about the same
time that the dependency on procfs was removed, so I'm probably missing
something.