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"