Re: [Help-bash] Fwd: Proper use of nohup within here-document?

[Greg Wooledge]

On Thu, Mar 22, 2018 at 12:04:20PM -0700, Mun wrote:
> My here-document looks something like this:
> 
> ========================================
> cat >myScript <<@EOF
> #! /bin/bash
> 
> date > showMe.txt
> nohup gxmessage -timeout 0 -file showMe.txt > /dev/null 2>&1 &
> 
> @EOF
> 
> chmod 777 myScript
> qsub -b yes -sync n ./myScript
> ========================================

So it's a script that writes a second script, and then executes the
second script.  There is no execution of background commands during the
here-document processing at all.  The background process is launched
by the second script.

P.S. 777 permissions are just wrong.  755 would be much more reasonable.

> Note the last line with the qsub command.  The whole purpose of the
> here-document is to package up a set of commands into a script form
> that will be dispatched to another server for execution using a "grid"
> tool (aka load sharing facility).
> 
> The commands run fine except I can't figure out a way for gxmessage to
> not die when myScript exits.

So the REAL question is how to run a long-running background command on
a remote system using this "grid" thing, which I'm going to assume is
something like ssh.

It looks like you've already redirected stdout and stderr, which is
the normal problem that people encounter when trying to run long-lived
background processes over ssh.

So, since I don't know anything about "gxmessage" or "grid", I don't know
that there's anything more I can do for you.  Sorry.  Maybe someone else
can take a stab at it.

Random guesswork:

(One possibility is that "grid" doesn't simply run a program, but
instead acts in coordination with some kind of remote overseer/supervisor
process, and this supervisor kills everything when "grid" disconnects,
in which case you are actively trying to subvert the design of the
system you're using.)

(Another is that gxmessage requires a terminal, and dies instantly
when executed by "grid" which I am assuming does not allocate a
pseudoterminal by default.)

(I'm sure there are a billion other random things that I just can't
think of at the moment.)

(Is there a support mailing list for "grid" and/or "gxmessage" that
might actually know such things?)