I have set up a cron job that need to be executed once a day but it is getting executed multiple times.I have set up it as I mentioned below:
5 8 * * * /sh_f
Without more knowledge about your particular setup/system, and the fact that all jobs get executed multiple times, I can only surmise that you have multiple cron daemons running on your system.
Do a full process list and grep for cron
(most of them have that word in the name of the binary) and see how many are running. On a standard linux system, this should work:
ps aux | grep cron
Then you would have to figure out which should be running and kill the others.