Linux – How to Prevent Running Task from Being Killed After SSH Logout

killlinuxshellssh

I have a computational task running for a few days on a linux server via SSH connection. It is not on the background, so the SSH connection is under hold of the task.

I want to restart the local machine (not the server) from which I have opened ssh session, but want to keep the task running. Is that any possible?

Best Answer

If your task is already launched, it is too late* to consider alternative solutions that insert an additional layer between your ssh session and the shell running the command, like screen, tmux, byobu, nohup and the likes.

If your process support to be placed in the background and particularly doesn't hang when stdout and stderr are unwritable/closed, you can put it in the background before logging out with ControlZ and bg then detach it from your shell with the disown builtin.

eg:

$ ssh localhost
You have new mail.
Last login: Fri Jun  6 11:26:56 2014

$ /bin/sleep 3600    


^Z[1] + Stopped                  /bin/sleep 3600
$ bg
[1] /bin/sleep 3600&
$ jobs
[1] +  Running                 /bin/sleep 3600
$ disown %1
$ exit
Connection to localhost closed.
$ ps -ef|grep sleep
jlliagre 12864     1  0 21:12 ?        00:00:00 /bin/sleep 3600
jlliagre 13056 12477  0 21:13 pts/18   00:00:00 grep sleep
$

* As Bob commented, there are actually several hackish ways to reparent a tty session under Linux. repty, retty, injcode and neercs. The most advanced looks to be reptyr but you might need root privileges to enable ptrace to hack your process.

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