Question

I am writing a shell script for a couple of long running processes.
First of all I need to run all commands in the screen session manager, so that the execution of a process does not end if a user has been disconnected.
Later I need wait for some background processes, which has been created before, to end, so that the following process can start.

My question is how to start a screen session in a shell script and wait for the background processes to end.

Answer 1

You can’t invoke screen (or nohup) on the running process, you have to do screen script. You could however do what nohup does, trap SIGHUP and redirect output to a file.

exec > OUT 2>&1
trap '' 1

To wait for background processes, save the pid when you create it and then call wait

foo&
PID1=$!
bar&
PID2=$1
wait $PID1 $PID2

Or alternatively just wait for everything to finish.

foo&
bar&
wait