The system of my VPS is centos 5. I want to know if it is 32bit or 64bit.

> uname -a
Thu May 13 13:49:53 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

looks like 64 bit.


> getconf WORD_BIT

Looks like 32 bit.

Which is correct?


I believe the linux of my VPS is 32 bit. Because I downloaded a 64bit mongodb, found it can't start. And when I downloaded a 32bit instead, it works well.

  • Why would you expect getconf WORD_BIT to tell you whether you have a 32-bit or a 64-bit OS? That makes no sense. – David Schwartz Apr 1 '16 at 17:29

Well, it depends. It's possible getconf doesn't return the correct value, and it's possible you have a 32-bit kernel on 64-bit hardware. I'd say, however, that the output of uname is what you should go by, as it states that you're running a 64-bit kernel.

  • I don't think it's possible that it's 32-bit kernel on 64-bit hardware if uname -a gives those results... – Andy Jul 10 '10 at 9:32

uname -a shows whether the OS is 32/64 bit.

  • welcome! fyi, getconf WORD_BIT returns 32 on my 64 bit Ubuntu. Also sizeof(int) is 32 bits... maybe that's what the getconf command is reporting. – Andy Jul 10 '10 at 9:30
  • I'd think sizeof(void*) would be the indicator – David Z Jul 10 '10 at 10:08
  • sizeof(void*) is going to be 8 bytes for 64 bit architectures no? I don't know what getconf WORD_BIT does, and was guessing it may be related to the size of an int because that actually is 32 bits! Edit: (on my current 64 bit OS...) – Andy Jul 10 '10 at 10:12
  • Indeed, the size of an int is not the arch size. This nice Wikipedia table shows how int sizes can be anywhere between ¼ word to 4 words on the 80486 family. – roguesys Jul 10 '10 at 15:39
  • The question still remains, is getconf WORD_BIT defined as the size of an int, or does it have some other meaning? – Andy Jul 11 '10 at 9:58

The glibc's WORD_BIT seems to be broken, because (in xopen_lim.h) it looks at __INT_MAX__ instead of __WORDSIZE or sizeof(__SWORD_TYPE).

To report the syscall personality of the current process, those commands are equivalent:

uname -m

To change it, assuming your kernel supports it:


It is possible to have a 64bit kernel with a 32bit userland. To know what kind of kernel you have:

sudo file /proc/kcore

Your CPU:

cat /proc/cpuinfo
  • It's broken because it does exactly what the standard requires it to do?! – David Schwartz Apr 1 '16 at 17:30
  • I looked at the standard link in your other comment. The definition (Number of bits in a word or type int) is ambiguous (and so is “exactly as required”), which makes it useless already; going with "size of an int" instead of "size of a word" as the name implies is a dubious choice. – Tobu Apr 6 '16 at 21:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.