What command do I type in to check this?


Is this a Linux server? If so, try uname -p


$ uname -p

Note that this only tells you about the Linux kernel, not any particular user-land software (e.g. you can still run 32-bit MySQL on 64-bit Linux). And you could be running 32-bit Linux on a 64-bit CPU.

  • D'oh. I just saw the "linux" tag, so of course it's a Linux server :-). – Matt Solnit Oct 8 '09 at 21:37

You could also check the cpuinfo and look for the "lm" (long mode) flag

less /proc/cpuinfo


flags : ... lm ....

a 32-bit processor won't have this flag.


In addition to Matt's answer about your kernel, if you're running a Red Hat/CentOS RPM-based distro (which is what most of Rackspace is, typically) you can check the installed userland tools for their bitness with this command:

rpm -qa --queryformat='%{n}-%{v}-%{r}.%{arch}\n' | sort

You're looking for .i386 or .x86_64 on the end. It's entirely possible to have a mix of 32bit and 64bit on a 64bit install based on needs of the server.

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