How to move job into background after already started

[dlite922]

i know to use nohup, but what if the user started a very long job and wanted to leave (logoff/logout) without killing the job.

Is there away to move an existing process into the background without restarting it?

This is a situation that came up by a colleague, but curious to know the answer for my future reference.


Thanks guys,


Dan

[AmberJain]

You can either nohup or detach a process. You can try using some terminal multiplexer (google tmux or screen) and then detaching the terminal before you logout.

[numberwhun]

Also, if you are running a process from the command line and the command line is tied up by the process and you need it back, you can do a "ctrl-Z" and then type bg.

That will background the process you have running.

Regards,

Jeff

[dlite922]

@numberwhun
But putting in in background then logging out, still keeps it going?

@Amber, ya, if it was a screen session, I could just detach it. Personally, I always use screen from my gateway host, but if I'm ever on some unusual host that away from our network doesn't have screen, I wouldn't know how to do it.

i'm going to test the bg method and log out, see if the job is still running. Will post back what I find.


Dan

[dlite922]

Worked!

Thanks @numberwhun


Dan

[numberwhun]

Unfortunately, no, if you log out it probably won't keep going. Its not nohup. But, it does allow you to get our command prompt back.

Also, if you have a program that you know is going to hijack your prompt, then put a & at the end of the line like so:

 
./command -opt1 -opt2 &
 
 

That will automatically background the job and give you your prompt back immediately.

Regards,

Jeff

[dlite922]

that's weird, here's what I did. A php script that in a for loop writes a number to a text file every few seconds. I ran it, Ctrl+Z, then bg and logged off. (when it was at 10)

logged back in about half a minute later and tail -f 'd the file and it was in the 20's or something. It was obviously running when I was offline.

I'll reconfirm and log off for a greater period or log in from another user's and follow the text file.

I'm pretty sure it kept running.


Dan

[numberwhun]

That is weird because ctrl-z is an interrupt.

[ashitpro]

try 'setsid' command...
It will create a process which will run your job and its parent will be init.
I am not sure about behavior after logoff.
But theoretically it should work as we are assigning it to init.