Start a screen session and run a script without attaching to it?

Question

I'm trying to write a script to:

1. Start a new screen session
2. Run some program or script within that new screen session
3. Detach from the screen session, while the program from step 2 may still be running in there. If the program from step 2 finishes, immediately or later, the screen session should remain running (detached).

I have been trying all sorts of combinations with screen -X program or screen -S somename followed by program followed by screen -D, combining with -d or -m options which I find in related questions and answers but nothing works.

The closest I could get was this:

screen -S MySessionName -d -m myprogram

This launches a new screen session in the backgroun, running myprogram. Except as soon as myprogram finishes (sometimes instantly) the screen session terminates, whereas I want to keep it running.

Solution

Method 1

I created a demo setup you described here in my machine. I also faced the issue you reported. But adding a small line of script solved my issue.

I added the following line at the end of myprogram

exec $SHELL

After your script is finished, the Bash process will replace itself with a new invocation of itself.

Method 2

Or you can try the following method in which we start a detached screen first and send command to that screen using stuff

For this first you need to start a detached screen.

screen -dmS MySessionName

And then send the script to that screen.

screen -S MySessionName -p 0 -X stuff 'myprogram\n'

This also worked for me.

Comments

[RocketNuts]

Brilliant, that 2nd method is perfect!

[pa4080]

Hi, Rooney, I'm not sure but probably you could change sleep infinity from Method 1 to exec bash or exec $SHELL - analogically to the solutions provided here: With a launcher for a terminal application, how can I keep the terminal open after the program is complete?

[Rooney]

Hi, @pa4080 You are right. thanks for the reply. Now the screen stays detached and i can continue to the screen, while using sleep infinity the only available option is terminate the screen manually.

[Scott Hather]

The second method is perfect for when my script crashes and doesn't get around to invokating itself. Many thanks!