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Old 02-18-2009, 02:01 AM   #1
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How to confirm Linux 32bit or 64bit

Hi, All

I have a question on RHEL4 AS4.

I want to confirm whether my linux support 64 bit. And what is the command?
I run uname -a which shows i386 and i686. I wonder whether i686 shows
Old 02-18-2009, 02:10 AM   #2
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i686 is 32 bit
Old 02-18-2009, 02:10 AM   #3
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Nope. i386 and i686 stat for 32-bit. Your kernel is 32-bit. There is a chance you're running a 32-bit OS on a 64-bit architecture, since you can do it without any problem. To check if your CPU is 64-bit, look at the output of
cat /proc/cpuinfo
in the flags section you have to look for lm (= long mode). If you see it, the CPU is 64-bit, if you don't see it the CPU is 32-bit. Anyway, you're running a 32-bit OS otherwise you should see x86_64 from the output of uname -a.

Last edited by colucix; 05-09-2010 at 04:16 PM.
Old 02-18-2009, 02:32 AM   #4
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Google for i386 and i686. Yep, they're 32-bit.
Old 02-18-2009, 02:15 PM   #5
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64-bit systems usually identify themselves as such by having '64-bit' or something similar in their kernel name , so running 'uname -a' should result in a string that gives you a hint, like
Linux box.domain #1 SMP Wed Sep 3 03:40:05 EDT 2008 i686 i686 i386 GNU/Linux
(this is a 32-bit system)


Last edited by servat78; 02-19-2009 at 11:30 AM.
Old 02-18-2009, 02:37 PM   #6
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With an PC architecture you should see "x86_64" in the uname string for 64 bit. However there is also an ia64 architecture for some specific Intel processors (but not all). Normally anything else (i386, i586, i686) is 32 bits, regardless of which processor it's running on.


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