Using screen in bash script

Question

I'm running a game server on a remote server where I use a detached screen instance to leave it running. I'm now creating a script that can be used to shut down the server, back up all the vital files and start it up again, however I'm having a few difficulties with dealing with the screen.

I assumed that I could just switch into the detached screen in the script (after the server had already been shut down) by calling screen -r in the script. But that doesn't seem to work because if I run the script from outside screen it just launches the server in that session.

screen -r
cd ~/servers/StarMade/
sh StarMade-dedicated-server-linux.sh
screen -d

This is what I thought would do the trick but it doesn't. Maybe somebody can help me out here. I'm not a bash expert. In fact this is propably my first bash script that doesn't include "Hello World". Thanks.

Answer 1

Your script, as in your example, will get executed by your sell, not the one in the screen. You need to tell the running screen to read a file and execute it - that's what the -X option is for.

Try

tempfile=$(mktemp)
cat > $tempfile <<EOF
cd ~/servers/StarMade/
sh StarMade-dedicated-server-linux.sh
EOF
screen -X readbuf $tempfile
screen -X paste .
rm -f $tempfile

You can leave screen running in a 2nd terminal session to see what happens.