linux

First option :
{code}cat /proc/net/dev{code}

This shows all network interfaces and some statistics associated with them, but is not very user friendly.

User friendly option : install Bandwidth Monitor NG (package name is bwm-ng in most common distribution) and execute it :
{code}bwm-ng{code}

It is now possible from kernel version 2.6.16 to drop Linux internal caches (page caches, inodes and dentry caches). This can be done by echoing a number into /proc/sys/vm/drop_caches :

To drop page cache :
echo 1 > /proc/sys/vm/drop_caches

To drop inode and dentry cache :
echo 2 > /proc/sys/vm/drop_caches

And finally to drop everything :
echo 3 > /proc/sys/vm/drop_caches

Source : Drop Caches - linux-mm.org