Path: utzoo!utgpu!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!EXPO.LCS.MIT.EDU!jim
From: jim@EXPO.LCS.MIT.EDU (Jim Fulton)
Newsgroups: comp.windows.x
Subject: Re: Shoudl X11R3 xterm really ignore SIGHUP's?
Message-ID: <8911052329.AA29134@kanga.lcs.mit.edu>
Date: 5 Nov 89 23:29:30 GMT
References: <1013@maxim.erbe.se>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: X Consortium, MIT Laboratory for Computer Science
Lines: 17


    What is the reason behind having xterm ignore SIGHUP's?  Makes a lot of
    xterm's keep floating around in the system when I turn my X terminal
    off. Would it be safe to remove all signal(SIGHUP, SIG_IGN); calls
    in xterm?

The SIGHUP handling to make sure that xterm and its subprocess end up in the
right group.  Removing them won't do you any good with your X terminal unless
you are running a session manager that periodically pings the server to see if
it is alive and then explicitly sends its own HUP signals.  

If you are using TCP to connect to the terminal, your host has no way of
knowing that the terminal went away unless your program or the kernel itself
tries to send some data (and your kernel keeps some sort of timeout for
deciding that a connection is dead as opposed to very slow).  Until XDMCP
is standardized and your vendor has implemented it, you probably shouldn't
turn your terminal off without shutting down your windows.