Clean RAM Cache in Linux

First of all check how much memory you have left :

mehdi@MPourhadi ~/> free -m

                     total     used         free    shared  buffers   cached

     Mem:    5968      5630         337     64        116        1038

     -/+ buffers/cache: 4475        1492

     Swap: 6139          56        6083

now issue the the command "sync" to flush the file system buffer. then change your root user.

For Debian-base users : "sudo bash" and for RPM packages "su or su -"

when you are root user issue the following command and see the diffrence :

root@MPourhadi:~/# echo 3 > /proc/sys/vm/drop_caches

      NOTE :

      echo 1 is for free pagecache

      echo 2 is for free dentries and inodes

      echo 3 is 1+2

root@MPourhadi:~/# free -m

                 total        used        free     shared      buffers       cached

     Mem:  5968        4399        1568      60            2               318

     -/+ buffers/cache: 4078 1889  

     Swap: 6139 56 6083