How to guide for running script or starting your custom coded daemon/service at system boot. Use RC script directory to load custom daemons at boot.
There are many daemons and system services which starts with system boot. You might be wondering how to add your own script or customized daemon or service in boot sequence so that when system is booted its there already running.
In this article, we will be seeing how to run your script with system boot in HPUX. First we will create a small script which will be taking start, stop arguments to call your original script/daemon/service. Then we will keep this script inside appropriate run level RC directory so that it will be executed when system enter that run level.
Lets assume you have /usr/sbin/my_agentd to start at boot. You can create a additional script /sbin/init.d/my_agent which can take start, stop options like below :
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | # cat /sbin/init.d/my_agent choice=$1 case $choice in "start") cd /usr/sbin ./my_agentd <other option if any> ;; "stop") ps -ef|grep -i my_agentd|grep -v grep|awk '{print $2}'|xargs kill -9 ;; esac |
Above script will take start and stop as arguments. It will execute your agent binary when supplied with start argument and kills your running agent if supplied with stop option. It is advisable to keep this script in /sbin/init.d directory since there lives all start,stop scripts of daemons or services.
Make sure you give proper executable permissions to this newly crafted script file.
1 2 3 | # chmod 555 /sbin/init.d/my_agent |
Now last step is to have this script executed with run-level 3 (multi user mode). To accomplish this, create a link for this file in /sbin/rc3.d directory.
/sbin/rc3.d directory contains all run level 3 related startup scripts. Keeping yours in it, makes sure that it will start with run level 3.
1 2 3 4 | # cd /sbin/rc3.d # ln -s /sbin/init.d/my_agent S99my_agent |
You are all set!
Now whenever your system enters run level 3. It will try to execute S99my_agent file with start argument. Which in turns calls /sbin/init.d/my_agent since its a link. When /sbin/init.d/my_agent (our coded script) gets start argument, it calls /usr/sbin/my_agentd which is your customized daemon/service/script.
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