How to Check OS Architecture 32 or 64 bit Ubuntu / CentOS / Debian / Linux

I know at least 2 ways. Open a terminal(Ctrl+Alt+T) and type:

Code:

uname -a

Result for 32-bit Ubuntu:

   

Code:

Linux discworld 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC 2011 i686 i686 i386 GNU/Linux

whereas the 64-bit Ubuntu will show:

Code:

Linux discworld 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

Shorter version:

$ uname -i
x86_64

or

file /sbin/init

Result for 32-bit Ubuntu:

/sbin/init: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, stripped

whereas for the 64-bit version it would look like:

/sbin/init: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.15, stripped

Same for systems using systemd (16.04):

Code:

file /lib/systemd/systemd

Result for 64-bit:

Code:

/lib/systemd/systemd: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically

---

Ubuntu 12.04+ with Unity

    Hit Command(mac) or Window key.
    Type Details, and select "Details" icon
    Read "OS type" field
    64 bit OS will read "64-bit"



Alternative to get the above screen:

    click System Menu (gear at top right corner)
    click "About this Computer"

I know the terminal responses are good but I guess this is the GUI answer. :)
Ubuntu 11.04 with Unity

    Hit Command(mac) or Window key.
    Type System info, and select System Info icon
    Read "OS type" field
    64 bit OS will read "64-bit"