AIX RC Scripts

We need some applications  should be stopped and started gracefully without manual intervention during the reboots . Order to serve this purpose , we use  rc scripts in all unix flavors including AIX  .

So, how do rc.scripts work:

1. Write a single script, put it into /etc/rc.d/init.d, make sure the script accepts a single parameter of start or stop and does the right thing.
2. In /etc/rc.d/rc2.d create a link (ln -s) to the script in init.d called Sxxname where xx is a number that dictates where in comparison to other scripts in the directory your script will execute (lower number first).
3. In /etc/rc.d/rc2.d create a link to the script in init.d called Kxxname where xx is a number which dictates when the script is run to stop your app in comparison to other scripts in the directory (lower number first).

Note: Its just convention to place scripts in /etc/rc.d/init.d and make  soft links  in /etc/rc.d/rc2.d. But its need not mandatory to keep  scripts in /etc/rc.d/init.d.

Example RC Script:

#!/usr/bin/ksh

ulimit -c 0

case "$1" in
start )
        ps -ef | grep -v grep | grep myengine > /dev/null
        ret=$?
        if [ $ret -gt 0 ]; then
                /var/myengine/bin/startup.sh
        fi
        ;;
stop )
        PID=$$
        for i in myengine-app1 myengine-app2 myengine-app3 myengine-app4; do
                ps -ef | grep $i | grep -v grep | awk '{print $2}' >> /tmp/myengine.$PID
        done
        while read line; do
                kill $line
        done < /tmp/myengine.$PID
        rm /tmp/myengine.$PID
        ;;
* )
        echo "Usage: $0 (start | stop)"
        exit 1
esac

Example Creating Symbolic Links

This is an example on creating symbolic links for automatic startup for tivoli. tivoli should start first (meaning a low Sxx) and stop last (meaning a high Kxx):

umadmin@umserve1:/etc/rc.d/rc2.d>sudo ln -s /etc/rc.d/init.d/rc.tivoli S20tivoli
umadmin@umserve1:/etc/rc.d/rc2.d>sudo ln -s /etc/rc.d/init.d/rc.tivoli K70tivoli