I want to start a long running custom script at boot.The script must run under a specific username.So far I have successfully used the screen command and switched to the user in the custom script. But I rather have the screen command run under that user so that I can later login to that user and resume the screen.This one does work when run as root in the console but it does not work as a line in a startup script.su -c screen -S sessionname -d -m /path/cot/bash/script username
Combined su and screen at startup
boot;gnu screen;startup;su
Under GNU/Linux at boot, you should not use su (as it depends on PAM/dbus, which may not be available yet), but runuser:runuser username -l -c screen -S sessionname -d -m /path/to/bash/scriptWhen using runuser followed by the user name, the syntax is the same as su.