I have custom applications for that I want to graphs the stats. Here is my requirement. I wrote a bash script which give me a numeric value and I am running that script from cron. Now I want that numeric data should be graphed via cacti using SNMP. I know its possible but not sure how?
Have your cron call rrdtool directly and make an RRD. It won't show in Cacti but it will make a graph. If you want it in Cacti, you would want to add some script to snmpd.conf that calls the script so Cacti can poll it.
You don't need to involve SNMP. Create a Data Input Method and use "Script/Command" as the Input Type, specifying the path your script.
Here's the relevant documentation page.
You might like to look at gnuplot.