How can I disown a running process and associate it to a new screen shell?
I have a running program on a SSH shell. I want to pause it and be able to unpause its execution when I come back.
One way I thought of doing that was to transfer its ownership to a screen shell, thus keeping it running in there.
Is there a different way to proceed?
You can revoke “ownership” of the program from the shell with the
# press Ctrl+Z to suspend the program bg disown
However this only tells the shell not to send a
SIGHUP signal to the program when the shell exits. The program will retain any connection it has with the terminal, usually as standard input, output and error streams. There is no way to reattach those to another terminal. (Screen works by emulating a terminal for each window, so the programs are attached to the screen window.)
It is possible to reattach the filedescriptors to a different file by attaching the program in a debugger (i.e. using
ptrace) and making it call
close. There are a few tools that do this; this is a tricky process, and sometimes they will crash the process instead. The possibilities include (links collected from answers to How can I disown a running process and associate it to a new screen shell? and Can I nohup/screen an already-started process?):
I don’t use it regularly, but neercs claims to support this. It’s a
screen-like program with miscellaneous fancy features like better pane management, but the main thing it offers is the ability to import a process into a pane
There’s also a small utility called retty that lets you reattach running programs to another terminal.
screen is your best bet.
Start screen running when you first login – I run
screen -D -R, run your command, and either disconnect or suspend it with
CTRL-Z and then disconnect from screen by pressing
When you login to the machine again, reconnect by running
screen -D -R. You will be in the same shell as before. You can run
jobs to see the suspended process if you did so, and run
%1 (or the respective job #) to foreground it again.
To move a process between terminals or to reattach a disowned, you can use e.g. reptyr.
My favorite solution is using
tmux, you could detach the session, and re-attach it in another terminal.
When you detached from previous session, you can safely close the terminal; later use
tmux attach to get back to the session, even if you logged out.
If you just want to pause it and restart afterwards, you can use
At first find out the processes PID with
$ ps aux
Then send the signals to that PID listed to the process
$ kill -STOP <PID> $ kill -CONT <PID>
“injcode” from ThomasHabets seems to be exactly the thing I need:
The injcode program allows arbitrary code to be injected into a running
process, whether or not you knew beforehand and were running screen or tmux
From the README:
Example 1: move irssi from one terminal to another
Maybe move it into a screen.
First start irssi in one terminal.
Run injcode in another terminal:
$ injcode -m retty
Irssi should now be moved to the second terminal, including having a new
This worked for me:
jobs -lfind process number
tmuxstart shell window manager
reptyr -L PROCESSNUMBER
-L was necessary to get this to work:
-L Like '-l', but also redirect the child's stdio to the slave.
because of this error:
$ reptyr 30622 [-] Unable to open the tty in the child. Unable to attach to pid 30622: Permission denied
And with -L
$ reptyr -L 30622 Opened a new pty: /dev/pts/4