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Is there a system command, in Linux, that reports the endianness?

lscpu

The lscpu command shows (among other things):

Byte Order:            Little Endian

Systems this is known to work on

  • CentOS 6
  • Ubuntu (12.04, 12.10, 13.04, 13.10, 14.04)
  • Fedora (17,18,19)
  • ArchLinux 2012+
  • Linux Mint Debian (therefore assuming Debian testing as well).

Systems this is known to not work on

  • Fedora 14
  • CentOS 5 (assuming RHEL5 because of this)

Why the apparent differences across distros?

After much digging I found out why. It looks like version util-linux version 2.19 was the first version that included the feature where lscpu shows you the output reporting your system's Endianness.

As a test I compiled both version 2.18 and 2.19 on my Fedora 14 system and the output below shows the differences:

util-linux 2.18

$ util-linux-ng-2.18/sys-utils/lscpu 
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
CPU(s):                4
Thread(s) per core:    2
Core(s) per socket:    2
CPU socket(s):         1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 37
Stepping:              5
CPU MHz:               1199.000
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

util-linux 2.19

$ util-linux-2.19/sys-utils/lscpu 
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
CPU socket(s):         1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 37
Stepping:              5
CPU MHz:               2667.000
BogoMIPS:              5320.02
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

The above versions were downloaded from the kernel.org website.

  • util-linux-ng-2.18.tar.bz2
  • util-linux-2.19.tar.gz

Using python:

$ python -c "import sys;print sys.byteorder"
little

or:

printf '\1' | od -dAn
1

where 1 is for little endian and 00256 for big endian.

Or using a shorter perl version:

$ perl -V:byteorder
byteorder='12345678';

One method I found on Debian/Ubuntu systems is to run this command:

$ dpkg-architecture
DEB_BUILD_ARCH=amd64
DEB_BUILD_ARCH_BITS=64
DEB_BUILD_ARCH_CPU=amd64
DEB_BUILD_ARCH_ENDIAN=little
DEB_BUILD_ARCH_OS=linux
DEB_BUILD_GNU_CPU=x86_64
DEB_BUILD_GNU_SYSTEM=linux-gnu
DEB_BUILD_GNU_TYPE=x86_64-linux-gnu
DEB_BUILD_MULTIARCH=x86_64-linux-gnu
DEB_HOST_ARCH=amd64
DEB_HOST_ARCH_BITS=64
DEB_HOST_ARCH_CPU=amd64
DEB_HOST_ARCH_ENDIAN=little
DEB_HOST_ARCH_OS=linux
DEB_HOST_GNU_CPU=x86_64
DEB_HOST_GNU_SYSTEM=linux-gnu
DEB_HOST_GNU_TYPE=x86_64-linux-gnu
DEB_HOST_MULTIARCH=x86_64-linux-gnu

This will show you the words little or big depending on the architecture your system is comprised of:

$ dpkg-architecture | grep -i end
DEB_BUILD_ARCH_ENDIAN=little
DEB_HOST_ARCH_ENDIAN=little