vm	Show memory usage.

	This program repeatedly displays current memory usage, showing the
	following numbers:

	* procs: number of processes; r - running, w - waiting for I/O,
		l - sleeping, s - swapping
	* virt mem: virtual memory amounts (total and active), in kB
	* real mem: real memory amounts (total and active), in kB
	* shared vm: amount of shared virtual memory (total and active), in kB
	* shared real: amount of shared real memory (total and active), in kB
	* free: amount of free memory, in kB