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 bit or 64 bit?

Answer 1

If you were running a 64 bit platform you would see x86_64 or something very similar in the output from uname -a

To get your specific machine hardware name run

uname -m

You can also call

getconf LONG_BIT

which returns either 32 or 64

Answer 2

Did you try uname -m ?

It seems like the uname -m actually gives

• x86_64 when it is an kernel 64 bits
• i686 for 32 bits kernel

---

Otherwise, not for the Linux kernel, but for the CPU, you type:

cat /proc/cpuinfo

or:

grep flags /proc/cpuinfo

Under "flags" parameter, you will see various values. Among them, one is named "tm(transparent mode)" or "rm(real mode)" or "lm(long mode)"

1. rm means: 16 bit processor
2. tm means: 32 bit processor
3. lm means: 64 bit processor

Note: you can have a 64-bit CPU with a 32-bit kernel installed"

Answer 3

That system is 32bit. iX86 in uname means it is a 32bit arch, if it was 64 bit it would return

Linux mars 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 x86_64 i686 x86_64 x86_64 GNU/Linux

Answer 4

If you have a 64 bits OS, instead of i686, you have x86_64 or ia64 in the output of uname -a In you do not have any of these 2 strings, you have a 32 bits OS (note that this does not mean that your CPU is not 64 bits)