Clean buffers and cached on linux

Need root permission

# clean buffer and cached
root@appv2-1:~# free -m && sync && echo 3 > /proc/sys/vm/drop_caches && free -m

# step by step
root@appv2-1:~# free -m
             total       used       free     shared    buffers     cached
Mem:          3951       3260        691          0         46        121
-/+ buffers/cache:       3092        859
Swap:         4095          0       4095

root@appv2-1:~# sync
root@appv2-1:~# echo 3 > /proc/sys/vm/drop_caches

root@appv2-1:~# free -m
             total       used       free     shared    buffers     cached
Mem:          3951       3065        886          0          2         22
-/+ buffers/cache:       3040        911
Swap:         4095          0       4095

Before:

• buffers = 46 mb

• cached = 121 mb

After

• buffers = 2 mb

• cached = 22 mb