Print operating system name.
Syntax uname [-amnpsrv] Options -a Behave as though all of the options -mnrsv were specified. -m Print the machine hardware name. -n Print the nodename (the nodename may be a name that the system is known by to a communications network). -p Print the generic processor type. -s Print the operating system name. This is the default if no other options are specified. -r Print the operating system release. -v Print the operating system version.
$ uname -m
$ uname -v
Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386
The version data includes either i386 or X86_64 indicating a 32 or 64 bit kernel. A 32-bit kernel is the default on most Apple computers, and this will still run 64-bit applications under Snow Leopard. Unless you are doing kernel/system-level development there is no need or benefit to running a 64-bit kernel.
During system boot you can hold down '6' and '4' to load the 64 bit kernel or hold down '3' and '2' to use the 32 bit kernel.
Your machine will default into the kernel that is best supported.
“I have discovered the art of deceiving diplomats. I tell them the truth and they never believe me” ~ Camillo Di Cavour
uname man page - Apple.com
hostname - Print or set system name.