linux_service.md

I need a reminder about how to set up a service in Linux that will run a script at boot time. Put this LSB init script in your /etc/init.d directory and then type

sudo update-rc.d linux_service.sh defaults

to set up the service. This is a wrapper for the script you actually want to run. The "Required-Start" section allows you to choose what Linux services need to be running before your own service is started. (I think my Fluidsynth script probably wants "alsasound".)

Some relevant links about this stuff:

• https://wiki.debian.org/LSBInitScripts
• https://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/initscrcomconv.html
• http://www.thegeekstuff.com/2012/03/lsbinit-script

linux_service.sh

#! /bin/sh
### BEGIN INIT INFO
# Provides:          hack
# Required-Start:    $syslog
# Required-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: An example of how to set up a service.
### END INIT INFO

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin

. /lib/lsb/init-functions

SCRIPT=/some/script/to/run/at/startup
PIDFILE=/var/run/hack.pid

start() {
    log_daemon_msg "Starting hack service"
    if [ -f $SCRIPT ]; then
        $SCRIPT &
        if [ "$?" != "0" ]; then
            log_failure_msg "The script failed"
        else
            echo $! > $PIDFILE
        fi
    fi
}

stop() {
    log_daemon_msg "Stopping hack service"
    if [ -f $PIDFILE ]; then
        kill -9 `cat $PIDFILE`
        rm -f $PIDFILE
    fi
}

case "$1" in
  start)
    start
    exit 0
    ;;
  stop)
    stop
    exit 0
    ;;
  restart)
    stop
    start
    exit 0
    ;;
  *)
    echo "Usage: /etc/init.d/hack.sh {start|stop|restart}"
    exit 1
    ;;
esac