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Killing an Xterm while leaving subprocess alive...

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Old 10-21-2005
Killing an Xterm while leaving subprocess alive...
Hi,
I'm not quite understanding what I'm doing (happens often). This pseudocode works:

#!/bin/pseudoksh

function kill_parent {
when i_want_to ; do
sleep 2
kill -TERM $PPID
exit
done
}

kill_parent &
ssh remote_host sh <<-EOF
notify_kill_parent # let the bg function know it's ok to kill parent
run_command # something x-based
EOF


Now, if I start my script in an xterm:
xterm -e run_my_script
It works as expected! The xterm pops up, ssh queries me for a password, the command runs and displays, and, seconds later, the xterm is killed. This is what I want to have happen. But I'm not sure why the remote shell and my application (run_command, above) still stick around. I've been pretty sloppy with stdin/stdout so I'm surprised they don't disappear when I kill the parent (xterm).

I'm happy it works, but I'm worried about a bug creeping in later- for example, since I'm not handling stdout, am I in danger of filling a buffer that is going to make the app hang? Or something like this.

I'm looking for insight into what happens when xterm calls ssh which calls a shell which calls a command. Xterm dies but the command does not. Why?
Thanks.
-Schwage
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LEARN ABOUT BSD

kill

KILL(1) 						      General Commands Manual							   KILL(1)

NAME

       kill - terminate a process with extreme prejudice

SYNOPSIS

       kill [ -sig ] processid ...
       kill -l

DESCRIPTION

       Kill  sends the TERM (terminate, 15) signal to the specified processes.	If a signal name or number preceded by `-' is given as first argu-
       ment, that signal is sent instead of terminate (see sigvec(2)).	 The  signal  names  are  listed  by  `kill  -l',  and	are  as  given	in
       /usr/include/signal.h, stripped of the common SIG prefix.

       The  terminate  signal  will  kill  processes  that do not catch the signal; `kill -9 ...' is a sure kill, as the KILL (9) signal cannot be
       caught.	By convention, if process number 0 is specified, all members in the process group  (i.e.  processes  resulting	from  the  current
       login)  are  signaled  (but  beware:  this works only if you use sh(1); not if you use csh(1).)	Negative process numbers also have special
       meanings; see kill(2) for details.

       The killed processes must belong to the current user unless he is the super-user.

       The process number of an asynchronous process started with `&' is reported by the shell.  Process numbers can also be found by using ps(1).
       Kill  is  a  built-in  to  csh(1); it allows job specifiers of the form ``%...'' as arguments so process id's are not as often used as kill
       arguments.  See csh(1) for details.

SEE ALSO

       csh(1), ps(1), kill(2), sigvec(2)

BUGS

       A replacement for ``kill 0'' for csh(1) users should be provided.

4th Berkeley Distribution					  April 20, 1986							   KILL(1)