Determine if an executable (or library) is 32 or 64 bit

Question

Is it possible to get information about any binary on OS X to determine if it's a 32 bit or 64 bit binary?

I played with the 'otool' command but can't find this kind of information.

Answer 1

Use the file command instead of otool. It will list all the architectures in the binary. On Intel Macs i386 is 32 bit and x86_64 is 64 bit.