Code for stopping the overlapping of the Cron job

Question

I need to stop the overlapping of cron jobs for example:If a cron job is scheduled at morning 2 o clock for DB backup and other cron job is scheduled at morning 7 o clock for DB backup again.So i need to stop the 7 o clock scheduled cron job if the DB backup for 2 o clock is not completed.

Answer 1

This is what flock is for. From man flock:

...
The  third form is convenient inside shell scripts, and is usually used
       the following manner:

       (
         flock -n 9 || exit 1
         # ... commands executed under lock ...
       ) 9>/var/lock/mylockfile
...

In this case, flock will try to get a lock on fd 9 for /var/lock/myfile. If it can't (because the earlier job is still running), it will exit.

You need to put it in a script.