Re: www/serf tty misbehavior

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Wed, 18 Dec 2013 18:14:51 -0500
    From:        Greg Troxel <gdt%ir.bbn.com@localhost>
    Message-ID:  <rmiob4dn444.fsf%fnord.ir.bbn.com@localhost>

  | ps alxw says that scons is at fault.

I expected that from your earlier message.

  | There is a need to clean; pkgsrc make won't actually run the build
  | target if work/.build_done is present.

If it got that far, then everything should have been essentially done,
and you would have been into the package building or install phase.
There should have been no need to build again, just continuing where you
left off should have worked (but then again, starting clean never really 
hurts.)

  | If I redirect stdin as well, the problem does not occur:
  |   make < /dev/null > /dev/null 2>&1 &
  | so the problem is that scons does something to stdin.

Yes.

  | So this is either a readline bug, or a bug in scons for invoking
  | readline when the input should not be read.

readline needs to put the terminal (stdin) into cbreak mode, so it can
do what it is designed to do - I guuess it could be made to wait until
something actually wants to read before doing that, but then - but then
typeahead wouldn't work cleanly, and for a basic library like readline
that probably wouldn't be desired.

I have no idea what scons is, what it does, or why it is being invoked at
all at this point, to have any idea whether it should be using readline,
or actually does need to read something (or attempt to), so I can't
comment on possible bugs in it.

In general, it is a good idea to redirect stdin from /dev/null in any
background process that you aren't expecting to return to the foreground
to interact with.  The shell can't do it by default, as it has no idea
what you were planning to do later...

kre