By default, every Linux OS has an efficient memory management system used to clear the buffer cache periodically. You can manually free up the memory cache with the following simple command:
sk@sk:~$ sudo sh -c “sync; echo 3 > /proc/sys/vm/drop_caches”
However, if you want to force the Linux OS to do clearing memory cache on a particular interval, just add the command to cron job. Here, I show you how.