km@mathcs.emory.edu (Ken Mandelberg) (06/26/89)
A/UX appears to only partially support the BSD semantics for control
terminals. Like BSD, it supports an extended version of setpgrp that
allows you to change the process group of a process into an existing
process group.
Unlike BSD, there is no provision for changing the control terminal of
a process to a tty that is already open. On BSD you can accomplish this
for example, with a TIOCNOTTY followed by an open of the desired
terminal (even if the terminal is already open).
In other words A/UX seems to strictly obey the System V semantics that
dictate that a proc's control terminal is either inherited from its
parent, or is associated with a terminal not already open (as it
establishes a new process group and becomes the process group leader).
This is not exactly what you want in a windowed environment. It is
very possible that you may want to hang a process off of a pty
(associated with some window) that is already open and not inherited.
In A/UX you can put the proc into that process group, but not change
its control terminal.
Is there a trick that I am missing?
What does POSIX say on the issue? I notice that the BSD doc clearly
allow the control terminal change, the SunOS doc "currently" allows it,
and the System V doc disallows it.
--
Ken Mandelberg | km@mathcs.emory.edu PREFERRED
Emory University | {decvax,gatech}!emory!km UUCP
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