Memory usage

Command: sar -r

      kbmemused
	     Amount of used memory in kilobytes. This does not take
	     into account memory used by the kernel itself.

      kbbuffers
	     Amount of memory used as buffers by the kernel in kilo-
	     bytes.

      kbcached
	     Amount of memory used to cache data by the kernel in
	     kilobytes.

	Here Total memory used is kbmemused, memory cached is kbcached
	and Memory used is (kbmemused - kbbuffers - kbcached).