The uname command will print system details. By default it shows the kernel name:
bpc steph # uname
Linux
The -a flag will show everything:
bpc steph # uname -a
Linux bpc 3.2.12-gentoo #11 SMP Sun Feb 3 22:19:46 GMT 2013 x86_64 Intel(R) Core(TM)2 Quad CPU Q6700 @ 2.66GHz GenuineIntel GNU/Linux
The -m flag will show the machine hardware name aka architecture:
bpc steph # uname -m
x86_64
There are other flags. Check out man uname.
