Creating a Debian init script

1) create sample init script

#! /bin/sh
# /etc/init.d/blah
#

# Some things that run always
touch /var/lock/blah

# Carry out specific functions when asked to by the system
case "$1" in
  start)
    echo "Starting script blah "
    echo "Could do more here"
    ;;
  stop)
    echo "Stopping script blah"
    echo "Could do more here"
    ;;
  *)
    echo "Usage: /etc/init.d/blah {start|stop}"
    exit 1
    ;;
esac

exit 0

2) add init script

root@skx:~# update-rc.d blah defaults
 Adding system startup for /etc/init.d/blah ...
   /etc/rc0.d/K20blah -> ../init.d/blah
   /etc/rc1.d/K20blah -> ../init.d/blah
   /etc/rc6.d/K20blah -> ../init.d/blah
   /etc/rc2.d/S20blah -> ../init.d/blah
   /etc/rc3.d/S20blah -> ../init.d/blah
   /etc/rc4.d/S20blah -> ../init.d/blah
   /etc/rc5.d/S20blah -> ../init.d/blah

3) remove init script

root@skx:/etc/rc2.d# update-rc.d -f  blah remove
update-rc.d: /etc/init.d/blah exists during rc.d purge (continuing)
 Removing any system startup links for /etc/init.d/blah ...
   /etc/rc0.d/K20blah
   /etc/rc1.d/K20blah
   /etc/rc2.d/S20blah
   /etc/rc3.d/S20blah
   /etc/rc4.d/S20blah
   /etc/rc5.d/S20blah
   /etc/rc6.d/K20blah