How To Find 32 bit or 64 bit in linux

Kernel version check



Type the following command at the terminal, run:
$ uname -a
Output:
Linux hostname 2.6.32-33-generic-pae #72-Ubuntu SMP Fri Jul 29 22:06:29 UTC 2011 i686 GNU/Linux

(or )

$ uname -m
Output:
i686


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.

$ getconf WORK_BIT
if you get 32 its 32bit kernel
if you get 64 its 64bit kernel

$ file /usr/bin/lsof
you could see the compilation version of the binary

/usr/bin/lsof: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, stripped

How to find out CPU is 32bit or 64bit?

type the following command and if you see lm in output, you have a 64 bit CPU based system:

$ grep flags /proc/cpuinfo

Output:

flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm tpr_shadow vnmi flexpriority
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm tpr_shadow vnmi flexpriority

CPU Modes:
lm flag means Long mode(lm) cpu - 64 bit CPU
Real mode 16 bit CPU
Protected Mode is 32-bit CPU

To find system support Hyper-v

$ grep vmx /proc/cpuinfo
Output:

flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm tpr_shadow vnmi flexpriority
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm tpr_shadow vnmi flexpriority

$ lshw
 command shows mainboard configuration, CPU version and speed, cache
       configuration, bus speed, etc