asked on

Daemon ?

How do i write a program that runs as a Daemon ?

Basically i want to achieve this :
I want to invoke a carry out a certain activity (liking invoking a certain application) based on time. That is, i schedule some activities for some time in future. Now, my appln. should continuosly check for time and if it is time to carry out that activity, simply do that, and continue running.

I guess, i must write a program that runs in background as a Daemon.

What language has to be used...Shell Script/C ?

How do i do this ?
Any available code ...
or info. on where i can find help on this would be helpful.

Thx.

sereda

You should use C.
man fork
man setsid
man exit
man chdir

scenario:
1. fork.
parent:
2. sleep a while;
3. exit;
child:
2. chdir "/";
3. setsid ()
4. infinite loop

If you want a code example, i think you should increate point cost ;)

tfewster

What's wrong with "cron"? What you have described is all done by cron, plus cron has security features and is started when the system boots. You program would have to be restarted if the system was rebooted, plus there would be an additional CPU overhead.

Jitu

ASKER

tfewster >
I am new to UNIX. I have no idea what is "cron" and how to use it...
Can u give some input or sample code..Thx.

sereda

$ crontab -e
-- your EDITOR appears
-- enter there:
* * * * * echo "Minute tick" > /dev/console
--- save file
===

Here is an example.
You will receive a message on console once per minute.

to get more information, run
man crontab
man cron

ASKER CERTIFIED SOLUTION

tfewster

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tfewster

Come on Jitu - As an expert yourself, you must know how frustrating it is to wait for someone to accept an answer!