How to monitor cron job using whenever gem and monit tools

Question

I am running a cron job that will pull data from facebook and stores in the database using whenever gem which is working properly.

I have monit(a monitoring tools) installed in the server and now i would like to monitor that cron job.

I searched a-lot but got nothing handy. What i have learnt that i need to create a pid file for the cron job using bash script and then i need to use that pid file in the monit configuration.

Can any one tell me how to create pid file using bash script for the cron job so that i can use that pid file in the monit.

i am using rvm ruby 2.2.3 and rails 4.1.2.