Available memory/disk space

Hi,

Is there any way to retrieve available RAM and available Disk space in a multiplatform command? Is it possible at all? or is the OS not providing this info?

Only info I`ve seen is this (not sure if it is multiplatform):

Thanks,
j

not sure about RAM usage.

but i use this to check hard drive capacity on OS X

Thank you for your answer @stephanschulz!