How to determine whether a given Linux is 32 bit or 64 bit?

Question

When I type `uname -a`, it gives the following output. Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux How can I know from this that the given OS is 32 or 64 bit? This is useful when writing `configure` scripts, for example: what architecture am I building for?

Answer 1

Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 i686 i386 GNU/Linux

explanation:

Linux - Operating System Kernel Name

mars - Hostname

2.6.9-67.0.15.ELsmp - Kernel release

#1 SMP Tue Apr 22 13:50:33 EDT 2008 - last time the kernel was compiled

i686 - Machine Architecture

i686 - Processor Archiecture

i386 - OS Architecture

GNU/Linux - Operating System

As you can see this is on i686 and i386 processor both of which are 32 bit