linux clean cache free Memory Usage code example
Example: linux memory cache clear
# clear pagecache only.
sync; echo 1 > /proc/sys/vm/drop_caches
# clear dentries and inodes.
sync; echo 2 > /proc/sys/vm/drop_caches
# clear pagecache, dentries and inodes.
sync; echo 3 > /proc/sys/vm/drop_caches