How to remove a data from main memory/RAM

Question

Is there any way to remove a specific data from the main memory in Linux ? So that is has to bring again that data from the hard-disk

Answer 1

Rather than removing a specific piece of data, this will remove all from the linux cache. (I am assuming this is what you mean when you want linux to reload a file from the hard disk into main memory).

sudo sh -c "sync; echo 3 > /proc/sys/vm/drop_caches"

Link: How to clear memory cache on linux

Also, my apologies to Mohit M. as he answered this in the comment section before me.

Answer 2

You could always change your app to use O_DIRECT flag which bypasses the page cache and fetches file from diskc for a specific read call. Now it may not work in all cases (especially in case of stacked block devices etc) in which case you should stick to drop_caches like other before me explained.