Listing 1: rc script to call the sentinel program

#!/bin/sh
#######################################################################
###                     /etc/init.d/sentinel                        ###
### This is the rc script used to start the "sentinel" program kept ###
### in "/usr/bill/progs".       Notice the use of "at" to delay the ###
### start of the  program  till after the  machine  is up for a few ###
### minutes.                                                        ###
#######################################################################

case $1 in
'start')
echo /usr/bill/progs/sentinel | at now +5 minutes   ### set delay
exit 0
;;
'stop')
exit 0
### no action
;;
*)
exit 1                                              ### error
;;
esac