[ale] After 15 years, Nohup is sttll broken???

Chris Fowler cfowler at outpostsentinel.com
Wed Jul 31 10:19:59 EDT 2019


> From: "Neal Rhodes via Ale" <ale at ale.org>
> To: "Jim Kinney" <jim.kinney at gmail.com>
> Cc: "Atlanta Linux Enthusiasts" <ale at ale.org>
> Sent: Wednesday, July 31, 2019 10:10:41 AM
> Subject: Re: [ale] After 15 years, Nohup is sttll broken???

> Well, indirectly - if the ssh session didn't die, it probably wouldn't
> happen.
I've been using keepalive SSH options for years to keep session up. I had system that did dialout ppp to servers with an idle timeout set for pppd. SSH session would drop so I used the keep alive out of band SSH messages to keep those connections up. I now use the same options for standard networks (real speeds). 

> BUT - isn't that the whole freaking point of nohup? No-Hang-Up?

> Wasn't the original point of nohup that I didn't want a modem
> disconnect, or accidently hitting CTRL-C on the keyboard, to kill a
> background job I had started?
I've always thrown nohup in the background on exection 

nohup ./script.sh & 

> What if I needed to start something via nohup, then shutdown my
> notebook, and drive home? My ssh session is gonna die.
tmux. Start the tmux session and run the job in a tmux pane. When you get home SSH back to the server and attach to the tmux session. I use this in development so I can occasionally check up on build status via JuiceSSH on Android. 

> Regards,

> Neal

> On 2019-07-31 09:05, Jim Kinney wrote:
> > Sounds like an ssh problem. Is keepalive set on?

> > On July 31, 2019 10:03:53 AM EDT, Neal Rhodes via Ale <ale at ale.org>
> > wrote:

> >> So, about 15 years ago, when we were transitioning from SCO Unix to
> >> Linux, we noticed that nohup didn't work on long running Progress
> >> Database jobs.

> >> We would start an update job via nohup, leave, several hours later
> >> the
> >> ssh session would timeout, and at some point the job would get a
> >> hangup
> >> signal and die. Which is sometimes really annoying if it's a 15
> >> hour
> >> job.

> >> Our workaround at the time was a script, "mynohup":

> >> #!/bin/bash
> >> set -x
> >> echo "at `date` Starting: $* " >> mynohup.out
> >> echo "$* >> mynohup.out " | at now
> >> set +x

> >> Which has worked flawlessly for 14.9 years.

> >> Now we are transitioning to new servers, running
> >> 2.6.32-696.30.1.el6.x86_64 #1 SMP Tue May 22 03:28:18 UTC 2018
> >> x86_64
> >> x86_64 x86_64 GNU/Linux

> >> inside VMs, and we experienced some awkwardness with some admin UI
> >> which
> >> had Apache -> PHP -> sh -> sudo - adminuser -> mynohup something.
> >> Barfing up some messages about tty devices. I thought of at least
> >> unwinding the old kluge.

> >> So, I thought, surely this has been fixed now, and tried running a
> >> job
> >> via nohup from an ssh session.

> >> Sure enough, at some point after leaving the office, the DB log
> >> shows....

> >> [2019/07/30 at 22:07:25.844-0500] P-28382 7: (562) HANGUP signal
> >> received.
> >> [2019/07/30 at 22:07:25.847-0500] P-28382 7: (453) Logout by neal on

> >> /dev/pts/4.
> >> [2019/07/30 at 22:07:28.241-0500] P-28439 8: (562) HANGUP signal
> >> received.
> >> [2019/07/30 at 22:07:28.241-0500] P-28439 8: (453) Logout by
> >> tdiadmin on
> >> batch.

> >> Wuh? The sole point of nohup is to not get a hangup, and ....????

> >> regards,

> >> Neal
> >> -------------------------
> >> Ale mailing list
> >> Ale at ale.org
> >> https://mail.ale.org/mailman/listinfo/ale
> >> See JOBS, ANNOUNCE and SCHOOLS lists at
> >> http://mail.ale.org/mailman/listinfo

> > --
> > Sent from my Android device with K-9 Mail. All tyopes are thumb
> > related and reflect authenticity.
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