Prevent GNU-Screen from blocking standard out

gnu-screen

We have screen running applications in production. (I have a feeling some may recommend against it, but it does work well for us, however …) If I scroll up in copy mode and then detach, forgetting to exit copy mode, the application blocks (I think after some time has elapsed).

What I believe is happening is the screen buffer gets filled up and cannot empty due to the active copy mode. This causes the running program to hang until reentering screen and exiting copy mode. I have made this mistake a number of times. Is there a way to prevent it? (e.g. automatically exiting copy mode when detaching, or being unable to detach whilst in copy mode). If not what about tmux or another drop in alternative?

Best Answer

Put a line with

defnonblock on

in ~/.screenrc

Also recommend

defflow off

to pass Ctrl-Q and Ctrl-S to applications instead of blocking screen output.

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Prevent GNU Screen from closing

Assuming you're using bash and accidentally closes the shell with Ctrl-D, you can

export IGNOREEOF=1

This will give you a warning and require you to press Ctrl-D twice, or type exit instead.

GNU Screen – Prevent Session Termination Once Executed Script Ends

To keep screen busy after the script completes, just keep something persistent running in a window. The simplest choice for that "something" is probably an interactive shell. Here's one way to do it (assuming bash as the choice of interactive shell):

screen -dmS session_name sh -c '/share/Sys/autorun/start_udp_listeners.sh; exec bash'

-dm: starts screen in detached mode
-S: sets session name for screen for easier retrieval later on
sh -c '...': instead of simply running your script, which will terminate, use sh -c to run multiple commands
exec bash: after the script terminates, the sh from above will switch over to an interactive shell (bash), which should never exit until something external terminates it. This will keep screen open as long as the bash instance is alive.

Best Answer

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Prevent GNU Screen from closing

GNU Screen – Prevent Session Termination Once Executed Script Ends

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