32 or 64 bit Linux

[Waqar Razi]

How can we know if the RHEL is 32 bits or 64 bit?

[Mel Burslan · Accepted solution]

$ uname -a
Linux test15 2.6.9-55.EL #1 Fri Apr 20 16:25:34 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux

The x86_64 says kernel is running on x86 series cpu, with 64 bit wide kernel.

[Ivan Ferreira]

You can use:

getconf LONG_BIT

[Waqar Razi]

uname -a
Linux APPLE 2.6.18-128.el5PAE #1 SMP Wed Dec 17 12:02:33 EST 2008 i686 i686 i386 GNU/Linux

It means it is 32 bit version?

[Mel Burslan]

Yup, it is 32 bit wide kernel. Also try Ivan's method to make sure it is. I never remember it when needed. Hence I resort to uname -a for the quick and dirty result display

[Hakki Aydin Ucar]

>Ivan:

when I issue the command in my customer's HP-UX server I am surprised:

getconf LONG_BIT
32

is it valid for HP-UX ?

[Matti_Kurkela]

Yes, getconf is included in POSIX standards, so it's available in many unix systems.

MK

[Dennis Handly]

>Hakki: when I issue the command in my customer's HP-UX server I am surprised: getconf LONG_BIT => 32
>is it valid for HP-UX?

It depends. Since all recent HP-UX servers only come in the color black, 64 bit, it is a waste of time checking. And the correct query is: KERNEL_BITS

Since HP-UX supports both ILP32 and LP64 at the same time, LONG_BIT is only valid for ILP32.
I don't know if sysconf(2) will change LONG_BIT to 64 in LP64?

[Hakki Aydin Ucar]

>Dennis: I tried to consolidate for HP-UX 32 or 64 bit under another Thread:

http://forums13.itrc.hp.com/service/forums/postQuestion.do?categoryId=156&forumId=1

please correct me if I am mistaken some steps, or put your comments there.

[Dennis Handly]

>ME: I don't know if sysconf(2) will change LONG_BIT to 64 in LP64?

It only returns 32. If you want the size, you can use sizeof.

>Hakki: I tried to consolidate for HP-UX 32 or 64 bit under another Thread:

You mean:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1365991

>put your comments there.

Bill has done a good job.

[Hakki Aydin Ucar]

>Dennis: You mean:
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1365991

Yes sorry about my typo :)

>>put your comments there.
>Bill has done a good job.

I am very agree.

[Ragu_3]

'uname -a' gives you the running kernel info/details. Maybe you wanted to know whether your cpu can run x86_64 instead of x86 binaries. The easy way to check that out is 'cat /proc/cpuinfo', if the flags section shows 'lm' or 'lahf_lm', you should install the x86_64/amd64 port of GNU/Linux. This correct port install would make your kernel access real RAM beyond 4GB, making it use system resources more optimally.

Hth.