[Trisquel-users] Is there a simple command to find out your architecture?

[mattij . lammi]

Hi,

I'm looking for a simple way to figure out a computer's architecture  
(Desktop, laptop, etc.). I'm contributing to www.h-node.org and would like to  
find out a way to tell quickly wether one's PC's architecture is one of the  
following four architectures:

x86
x86-64/amd64
MIPS
ARM

A few commands in bash are preferred over some GUI applications. Your help is  
most appreciated. Thanks in advance.