GNU Screen – Sending Input to a Screen Session from Outside

gnu-screen

My scenario is this:

I have a screen session running in a remote location. Inside this screen is a consoled-based program. When run without screen, this program starts in the terminal and accepts commands on its standard input.

What I want is a way to remotely send a command to screen so that this command is received by the console program. Maybe like this:

My PC -> SSH Send Msg Auto -> Screen Session -> Program (Run command received)

So from a remote PC I can send via SSH commands to the screen which sends them to the program. The program accepts them and executes them.

Best Answer

If I understand correctly, you want to send input to a program running inside a screen session. You can do this with screen's stuff command. Use screen's -X option to execute a command in a screen session without attaching to it.

screen -S sessionname -p windowname -X stuff 'command1
command2
'

If you want to see the program's output, see the hardcopy, log and logfile commands.

Related Solutions

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.

Ssh – Remotely starting a screen session through ssh and closing the ssh session immediately

You can use -d -m to your screen session to do it like:

ssh myuser@hostname screen -d -m "python somepath.py -s 'potato'"

That will create a new screen session, run your command in it and automatically detach you from it.

That option is documented as

-d -m
Start screen in detached mode. This creates a new session but doesn't attach to it. This is useful for system startup scripts.

on the GNU documentation page for screen

Best Answer

Related Solutions

GNU Screen – Prevent Session Termination Once Executed Script Ends

Ssh – Remotely starting a screen session through ssh and closing the ssh session immediately

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