Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!ncrlnk!ncrcce!mercer
From: mercer@ncrcce.StPaul.NCR.COM (Dan Mercer)
Newsgroups: comp.unix.questions
Subject: Re: setpgrp question
Message-ID: <1802@ncrcce.StPaul.NCR.COM>
Date: 27 Dec 89 04:47:08 GMT
References: <6863@cbnewsh.ATT.COM> <1989Dec24.222740.8645@virtech.uucp>
Reply-To: mercer@ncrcce.StPaul.NCR.COM (Dan Mercer)
Organization: NCR Comten, Inc.
Lines: 29
Keywords:setpgrp, unix system call

In article <1989Dec24.222740.8645@virtech.uucp> cpcahil@virtech.uucp (Conor P. Cahill) writes:
:In article <6863@cbnewsh.ATT.COM>, skumar@cbnewsh.ATT.COM (swaminathan.ravikumar) writes:
:
:> By reading different sources I found out that a process can
:> break its control terminal by calling "setpgrp". I don't
:> understand this 100%. Why should the process lose the control
:> terminal? why do you need "setpgrp"?
:
:setpgrp() is one of the steps that should be executed by a daemon
:process at initialization time.  It does disconnect the terminal from 
:the controll tty and therefore should only be used by programs that
:no longer wish to be associated with a terminal.

For instance,  in the telecommunications program PCOMM,  patterned
closely after PROCOMM(tm),  the input process originally generated
SIGHUP back to the controlling terminal when the dial-out line hung
up.  I was one of the first to notice the problem,  since I have
a personal daemon running in background that provides me special
services within vi.  Adding a setpgrp() to the input routine cleared
the problem and was later added by a patch level.

The Token Ring NetBIOS software for the NCR Tower has the same problem
with nlogin,  which allows login sessions across the ring.


-- 

Dan Mercer
Reply-To: mercer@ncrcce.StPaul.NCR.COM (Dan Mercer)