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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 DEBIAN

pperl

PPERL(1p)						User Contributed Perl Documentation						 PPERL(1p)

NAME

       PPerl - Make perl scripts persistent in memory

SYNOPSIS

	 $ pperl foo.pl

DESCRIPTION

       This program turns ordinary perl scripts into long running daemons, making subsequent executions extremely fast. It forks several processes
       for each script, allowing many processes to call the script at once.

       It works a lot like SpeedyCGI, but is written a little differently. I didn't use the SpeedyCGI codebase, because I couldn't get it to
       compile, and needed something ASAP.

       The easiest way to use this is to change your shebang line from:

	 #!/usr/bin/perl -w

       To use pperl instead:

	 #!/usr/bin/pperl -w

WARNINGS

       Like other persistent environments, this one has problems with things like BEGIN blocks, global variables, etc. So beware, and try checking
       the mod_perl guide at http://perl.apache.org/guide/ for lots of information that applies to many persistent perl environments.

Parameters
	 $ pperl <perl params> -- <pperl params> scriptname <script params>

       The perl params are sent to the perl binary the first time it is started up.  See perlrun for details.

       The pperl params control how pperl works. Try -h for an overview.

       The script params are passed to the script on every invocation. The script also gets any current environment variables, the current working
       directory, and everything on STDIN.

Killing
       In order to kill a currently running PPerl process, use:

	 pperl -- -k <scriptname>

       You need to make sure the path to the script is the same as when it was invoked.

       Alternatively look for a .pid file for the script in your tmp directory, and kill (with SIGINT) the process with that PID.

ENVIRONMENT

       pperl uses the PPERL_TMP_PATH environment variable to determine the directory where to store the files used for inter-process
       communication.  By default, the subdirectory .pperl of the user's home directory is used.

BUGS

       The process does not reload when the script or modules change.

       $^S is not represented identically with respect to perl, since your script will be run within an eval block

AUTHOR

       Matt Sergeant, matt@sergeant.org. Copyright 2001 MessageLabs Ltd.

SEE ALSO

       perl. perlrun.

perl v5.14.2							    2011-11-15								 PPERL(1p)