Maintaining Screen Output
The following snippet of shell code demonstrates the solution I’ve discovered for this problem. It determines whether SCREEN is the parent process of the shell script and if so it sleeps for 60 seconds before exiting so I can see the KVM error messages. The other option is for the script to call “exec bash” to give me a new shell in the same window. Note that if I start a screen session and then run my KVM script I don’t want it to do anything special on exit as I will return to the command-line in the same window. If I run “exec kvm-unstable” or have a system boot script run “start-stop-daemon -S -c USER --exec /usr/bin/screen -- -S kvm-unstable -d -m /usr/local/bin/kvm-unstable” then on exit I will be able to see what happened.
#!/bin/bash
set -e
kvm ETC || echo “KVM gave an error return code”
COUNT=$(ps aux|grep $PPID|grep SCREEN|wc -l)
if [ "$COUNT" = "1" ]; then
echo "screen is the parent"
sleep 60
else
echo no screen
fi
Update: Thanks to John for the Slee for suggesting the following:
#!/bin/bash
set -e
kvm ETC || echo “KVM gave an error return code”
if grep -q SCREEN /proc/$PPID/cmdline ; then
echo "screen is the parent"
sleep 60
else
echo no screen
fi