How to tell if a Linux system is big endian or little endian?
Solution 1:
On a Big Endian-System (Solaris on SPARC)
$ echo -n I | od -to2 | head -n1 | cut -f2 -d" " | cut -c6
0
On a little endian system (Linux on x86)
$ echo -n I | od -to2 | head -n1 | cut -f2 -d" " | cut -c6
1
The solution above is clever and works great for Linux *86 and Solaris Sparc.
I needed a shell-only (no Perl) solution that also worked on AIX/Power and HPUX/Itanium. Unfortunately the last two don't play nice: AIX reports "6" and HPUX gives an empty line.
Using your solution, I was able to craft something that worked on all these Unix systems:
$ echo I | tr -d [:space:] | od -to2 | head -n1 | awk '{print $2}' | cut -c6
Regarding the Python solution someone posted, it does not work in Jython because the JVM treats everything as Big. If anyone can get it to work in Jython, please post!
Also, I found this, which explains the endianness of various platforms. Some hardware can operate in either mode depending on what the O/S selects: http://labs.hoffmanlabs.com/node/544
If you're going to use awk this line can be simplified to:
echo -n I | od -to2 | awk '{ print substr($2,6,1); exit}'
For small Linux boxes that don't have 'od' (say OpenWrt) then try 'hexdump':
echo -n I | hexdump -o | awk '{ print substr($2,6,1); exit}'
Solution 2:
If you are on a fairly recent Linux machine (most anything after 2012) then lscpu now contains this information:
$ lscpu | grep Endian
Byte Order: Little Endian
This was added to lscpu in version 2.19, which is found in Fedora >= 17, CentOS >= 6.0, Ubuntu >= 12.04.
Note that I found this answer from this terrific answer on Unix.SE. That answer has a lot of relevant information, this post is just a summary of it.
Solution 3:
Here is a more elegant python one-line script
python -c "import sys;sys.exit(0 if sys.byteorder=='big' else 1)"
exit code 0 means big endian and 1 means little endian
or just change sys.exit to print for a printable output
Solution 4:
You can take advantage of ELF file format to determine the endianness of your system. For example, print the first six bytes of an arbitrary ELF file in hex:
xxd -c 1 -l 6 /bin/ls
0000000: 7f .
0000001: 45 E
0000002: 4c L
0000003: 46 F
0000004: 02 .
0000005: 01 .
If the last line (the sixed byte) is 01, according to ELF format, 01 is little endian and 02 is big endian.
If you haven't got an xxd on your box (and do have busybox), try this:
hexdump -s 5 -n 1 -C /bin/busybox
Solution 5:
The main answer can be simplified slightly using awk:
On a Big Endian system (Solaris, SPARC)
$ echo -n I | od -to2 | awk 'FNR==1{ print substr($2,6,1)}'
0
On a Little Endian system (Linux, Intel)
$ echo -n I | od -to2 | awk 'FNR==1{ print substr($2,6,1)}'
1
Newer Linux Kernels
As of version 2.19 of the util-linux package the command lscpu started including a field related to Endianness. So now you can simply use this command to find this out:
$ lscpu | grep -i byte
Byte Order: Little Endian
This has been confirmed on Ubuntu 12.10 and CentOS 6. So I would be willing to assume that most 3.0+ Linux Kernels are now offering this.
On Debian/Ubuntu systems you can also use this command, not sure of when it became available:
$ dpkg-architecture | grep -i end
DEB_BUILD_ARCH_ENDIAN=little
DEB_HOST_ARCH_ENDIAN=little
References
- Is there a system command, in Linux, that reports the endianness?