CLI Tools: screen

One of my favourite CLI tools is screen. Basically it lets you detach from your shell session and it keeps running. You can reattach to it later from anywhere, start your shell from a local TTY then reattach via SSH. You can even share your session and have others join in so you can collaborate on shell.

The sample code for today is how to make an init script to run your program as a detached daemon using screen. The cool thing about this is it lets you connect to it at any time to see what it is doing. This is not recommend for normal use but it is a great way to debug that new program before you commit to making it a proper daemon.

#!/bin/bash

cd /etc/init.d

start() {
 echo "Starting Service: "
 APP_CMD="/usr/local/bin/MyProgram.pl"
 screen -dmS pmsgd $APP_CMD
 echo
}

stop() {
 echo "Cannot stop screen programs this way. Open the screen sessions."
 echo
}

restart() {
 stop
 start
}

# See how we were called.
case "$1" in
  start)
 start
 ;;
  stop)
 stop
 ;;
  restart)
 restart
 ;;
  *)
 printf "Usage: %s {start|stop|restart}\n" "$0"
 exit 1
esac

exit 0