23 Sep
2017
23 Sep
'17
2:57 a.m.
In that sense, job control and process groups *are*
independent of
the terminal device.
The complication arises when you have to multiplex one terminal
between several different jobs in an interactive shell. Setting
the terminal process group correctly -- the only way to accomplish
that -- is fragile and the consequences of setting it to the wrong
value are inconvenient, to say the least.
Sure, but here again you can have the shell hang on to the
(kernel allocated) pgroup, and any control operation amounts
to, e.g., "set tty pgroup to the one for my pgroupid X".
Since the shell is waiting for everything in the pipeline
to exit, the shell knows when to close its "pgid descriptor".
(If you abandon the pipeline entirely, you also abandon the
ability to attach it to a tty. There should be some way to
"rejoin" pgroups, which would let you attach them to new tty
sessions, which is something that is missing from the current
system. But that's another thing entirely.)
Chris