Linux Initscript Example to start and stop process during booting

The below shell script uses start-stop-daemon from “/sbin/start-stop-daemon” to execute the program during booting so that the process is started boottime. In the below example, DAEMON=$PWD/helloworld.bin shows that our program is helloworld.bin and is located in current directory from where the script is executed.

$ vim start_daemon.sh

#!/bin/sh
# Must be a valid filename
NAME=helloworld
PIDFILE=/var/run/$NAME.pid
#This is the command to be run, give the full pathname
DAEMON=$PWD/helloworld.bin
DAEMON_OPTS="--baz=quux"

export PATH="${PATH:+$PATH:}/usr/sbin:/sbin"

case "$1" in
  start)
        echo -n "Starting daemon: "$NAME
	start-stop-daemon --start -m --background --quiet --pidfile $PIDFILE --startas $DAEMON -- $DAEMON_OPTS
        echo "."
	;;
  stop)
        echo -n "Stopping daemon: "$NAME
	start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE
        echo "."
	;;
  restart)
        echo -n "Restarting daemon: "$NAME
	start-stop-daemon --stop --quiet --oknodo --retry 30 --pidfile $PIDFILE
	start-stop-daemon --start -m --background --quiet --pidfile $PIDFILE --startas $DAEMON -- $DAEMON_OPTS
	echo "."
	;;

  *)
	echo "Usage: "$1" {start|stop|restart}"
	exit 1
esac

exit 0

The above script can be executed as “bash start_daemon.sh start” to start the daemon.

If we want this initscript to be executed everytime during booting sequence, then we need to copy this to /etc/init.d and run the update-rc.d command once as below,

$ chmod 777 start_daemon.sh
$ sudo mv start_daemon.sh /etc/init.d/start_daemon
$ sudo update-rc.d start_daemon defaults
$ sudo reboot