How to determine Linux kernel architecture?

Question

uname -m gives i686 and uname -m gives i686 i386 output in Red Hat Enterprise Linux Server release 5.4 (Tikanga) machine. I need to install Oracle Database 10g Release 2 on that machine. So, how can I decide whether kernel architecture is 32bit or 64bit?

Answer 1

i386 and i686 are both 32-bit.
x86_64 is 64-bit

example for 64 bit:

behrooz@behrooz:~$ uname -a  
Linux behrooz 2.6.32-5-amd64 #1 SMP Mon Mar 7 21:35:22 UTC 2011 **x86_64** GNU/Linux

EDIT:
See is my linux ARM 32 or 64 bit? for ARM

Answer 2

It's simple! Use the arch command from coreutils package.

Answer 3

For Debian:

On my PC

    ~ > dpkg --print-architecture
    amd64

    ~ > dpkg --print-foreign-architectures
    i386

My Raspberry Pi 2

    ~ > dpkg --print-architecture
    armhf

Answer 4

@behrooz is correct. Unfortunately uname requires you to know architectures. Actually, I was looking for a list of architectures and I found this article that answers your question. In regards to uname -m:

x86_64 GNU/Linux indicates that you've a 64bit Linux kernel running. If you use see i386/i486/i586/i686 it is a 32 bit kernel.

To determine if the hardware is capable of running a 64-bit kernel

grep flags /proc/cpuinfo

Look for the following in the output (all flags retrieved from this stackoverflow answer for the same question )

• lm flag means Long mode cpu - 64 bit CPU
• tm flag means Protected mode - 32-bit CPU
• rm flag means Real Mode - 16 bit CPU

Answer 5

The simplest way is to run:

getconf LONG_BIT

which will output 64 or 32 depending on whether it is 32 or 64 bits.

eg:

dannyw@dannyw-redhat:~$ getconf LONG_BIT
64

Answer 6

There is also lscpu: display information about the CPU architecture

lscpu
Architektura:                    x86_64
Tryb(y) pracy CPU:               32-bit, 64-bit
Kolejność bajtów:                Little Endian
Address sizes:                   39 bits physical, 48 bits virtual
CPU:                             8
Lista aktywnych CPU:             0-7
Wątków na rdzeń:                 2
Rdzeni na gniazdo:               4
Gniazd:                          1
Węzłów NUMA:                     1
ID producenta:                   GenuineIntel
Rodzina CPU:                     6
Model:                           60
Nazwa modelu:                    Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
Wersja:                          3
CPU MHz:                         3392.293
CPU max MHz:                     3900,0000
CPU min MHz:                     800,0000
BogoMIPS:                        6784.24
Wirtualizacja:                   VT-x
Cache L1d:                       128 KiB
Cache L1i:                       128 KiB
Cache L2:                        1 MiB
Cache L3:                        8 MiB
Procesory węzła NUMA 0:          0-7

Answer 7

use syscap from Formake project

syscap allows to probe many system properties and test dependencies. It is a portable shell script.

Get CPU architecture:

syscap info -arch

Get kernel name and version:

syscap info -kernel -kernver

Answer 8

Here's another method using uname.

From uname(1):

...

-i, --hardware-platform
print the hardware platform or "unknown"

...

# uname -i
x86_64

#

Answer 9

Another way is to check the architecture some system file was compiled for, like

$ file /usr/bin/ld
/usr/bin/ld: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, stripped

Answer 10

Or you can use the way of what the uname command internally does if you want to implement some stuff on your own:

#include <sys/utsname.h>
#include <stdio.h>

int main() {
    struct utsname name;
    uname(&name);
    printf("%s\n",name.machine);
    return 0;
}

Answer 11

If you're looking for a simple one-liner, this is the most reliable solution that I've found that returns 64 or 32. It doesn't care if you're running ARM or not, and it should work on any system using bash or sh.

Beware, this will assume the system is either 32-bit or 64-bit. See my explanation below if you need to detect 8- 16- or some-other-bit architecture.

[ $((0xffffffff)) -eq -1 ] && echo 32 || echo 64

What's happing here?
The logic is very simple and it all boils down to how computers store signed integers. A 32-bit architecture only has 32 bits that it can use for storing signed integers while a 64-bit architecture has 64 bits! In other words the set of integers that can be stored is finite. Half of this set represents negative numbers and half represents positive numbers. The signed integer equalling -1 is represented as the largest number that can be stored in a given number of bits for that architecture. On a 32-bit system, -1 can be represented by the hex value 0xFFFFFFFF (which is 32 binary bits, all equalling 1). On a 64-bit system, 0xFFFFFFFF translates to 4,294,967,295, base 10 while 0xFFFFFFFFFFFFFFFF is the representation for -1). You can see how this would easily scale for systems that are 8- or 16-bit as well which would equal -1 at 0xFF and 0xFFFF, respectively.

Answer 12

For debian Linux derived systems.

On 64bits systems :

$ dpkg-architecture -q DEB_BUILD_ARCH
amd64

On 32bits systems :

$ dpkg-architecture -q DEB_BUILD_ARCH
i386

Answer 13

Not sure how useful this is, but I crafted this for Arch:

grep "model name" /proc/cpuinfo | sed "s/model name   : //" | head -n 1

(Only answered because I searched for Arch and found this; I know the OP asked about Red Hat.)

Answer 14

This is a small bash function that helped my a lot:

initArch() {
  ARCH=$(uname -m)
  case $ARCH in
    armv5*) ARCH="armv5";;
    armv6*) ARCH="armv6";;
    armv7*) ARCH="arm";;
    aarch64) ARCH="arm64";;
    x86) ARCH="386";;
    x86_64) ARCH="amd64";;
    i686) ARCH="386";;
    i386) ARCH="386";;
  esac
}

In my case, uname -m gives me x86_64, but the binary I am trying to dowload refers to it as amd64.

This code is part of the get_helm.sh script to install helm binary.