Vishal Gupta's Blog

Normally DBAs and SAs have a tendency to create the auto start/stop scripts like following.

# cat /etc/init.d/oracle
case $1 in
start)
 /opt/oracle/product/11.1.0/bin/dbstart;
 ;;
stop)
 /opt/oracle/product/11.1.0/bin/dbshut;
 ;;
esac

# ln -s /etc/init.d/Oracle /etc/rc.d/rc0.d/K01oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc3.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc4.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc5.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc6.d/K01oracle

This works fine on non-Linux operating systems. But on Linux operating system, there is an requirement to for start/stop script to create/remove a /var/lock/subsys/ file, where is name of the file in /etc/init.d. This ensures that, when init is changing runlevel as part of server start and stop routine, a service which is already started does not start again. And a service which is already stopped does not stop again. If /var/lock/subsys/ is not created then inspite of K(ill) symbolic links being present in rc*.d folder for runlevel zero (halt) and 6 (reboot), stop script is not called. This means process are killed instead of being shutdown cleanly by your stop script.

On Linux Operating system, start/stop functions for a service init.d script should look like below. Important part is highlighted in red below

# chkconfig: 2345 99 01

# description: This script start/stop Oracle

case $1 in
start)
   /opt/oracle/product/11.1.0/bin/dbstart;
    touch /var/lock/subsys/Oracle;
    # where  is same as name of file in /etc/init.d
    ;;
stop)
    /opt/oracle/product/11.1.0/bin/dbshut;
    rm –f /var/lock/subsys/Oracle; 
    ;;
esac

# ln -s /etc/init.d/Oracle /etc/rc.d/rc0.d/K01oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc3.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc4.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc5.d/S99oracle
# ln -s /etc/init.d/Oracle /etc/rc.d/rc6.d/K01oracle

This applies to not only oracle but all start/stop created for init.d on Linux.

This requirement to create subsystem lock file in /var/lock/subsys can be verified by looking at /etc/rc script, which is called everytime there is runlevel change. See below the portion of /etc/rc script which is checking for presense of /var/lock/subsys/ file before calling Kill/stop scripts.

# First, run the KILL scripts.
for i in /etc/rc$runlevel.d/K* ; do
   check_runlevel "$i" || continue

   # Check if the subsystem is already up.
   subsys=${i#/etc/rc$runlevel.d/K??}
   [ -f /var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] \
    || continue

   # Bring the subsystem down.
   if LC_ALL=C egrep -q "^..*init.d/functions" $i ; then
      $i stop
   else
      action $"Stopping $subsys: " $i stop
   fi
done