Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!cos!hqda-ai!merlin
From: merlin@hqda-ai.UUCP (David S. Hayes)
Newsgroups: comp.unix.questions
Subject: Re: BSD and setpgrp()
Message-ID: <541@hqda-ai.UUCP>
Date: Mon, 23-Nov-87 11:30:58 EST
Article-I.D.: hqda-ai.541
Posted: Mon Nov 23 11:30:58 1987
Date-Received: Thu, 26-Nov-87 01:13:16 EST
References: <341@n8emr.UUCP>
Organization: Army AI Center, Pentagon
Lines: 16
Keywords: setpgrp system calls stdin
Summary: Process group controls access to the control terminal.


     BSD (for those who are afflicted with Sys V) allows a user to
move jobs between the foreground and background at will.  It does
this by assigning every process a "process group".  The terminal
also has a process group associated with it.  Only those processes
in the current process group for the control terminal can access
the terminal.  The C-shell controls what process is in the
foreground by changing the process group of the terminal.

     For other jobs, the process is given either SIGTTOU (when
writing) or SIGTTIN (when reading).  This applies only to the
control terminals - streams (BSD FILE *) to other terminals are
unaffected.
-- 
David S. Hayes, The Merlin of Avalon	PhoneNet:  (202) 694-6900
UUCP:  *!uunet!cos!hqda-ai!merlin	ARPA:  ai01@hios-pent.arpa