Q. How can I check if my server is running on a 64 bit processor and running 64 bit OS or 32 bit operating system?

Before answering above question we have to understand below points.

We can run a 32-bit Operating system on a 64 bit processor/system.
We can run a 64-bit operating system on a 64 bit processor/system.
We cannot run a 64-bit operating system on a 32-bit processor/system.
We can run a 32-bit operating system on a 32-bit processor/system.

Once we are clear about the above 4 points then we can see if our machine have a 64 bit processor or not.

How to check if my CPU is a 64-bit supported processor or not?

There are two commands to check if it’s a 64 bit processor or not

Option 1 : use lscpu command to check if it supports multiple CPU operation modes(either 16, 32 or 64 bit mode).

as a normal/root user execute below command

lscpu | grep op-mode

Sample output on a 64-bit processor

[email protected]:~$ lscpu | grep op-mode
CPU op-mode(s): 32-bit, 64-bit

Sample output on a 32-bit processor

[[email protected] ~]$ lscpu | grep op-mode
CPU op-mode(s): 32-bit

If you observe the first output will say that your CPU supports both 32-bit as well as 64 bit operating systems. This indicates that it’s 64-bit processor from our above 4 rules. But in the second machine it say’s only 32-bit CPU mode which indicates it’s a 32 bit processor.

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Option 2: Use proc file system file CPU info to get the processor type.

grep -w lm /proc/cpuinfo

Sample output on a 64-bit processor when searching for lm(long mode) bit is set or not

grep -w lm /proc/cpuinfo
flags : tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr

Sample output on a 32-bit processor when search for lm(long mode) bit.

grep -w lm /proc/cpuinfo
[[email protected] ~]$ grep lm /proc/cpuinfo

If you don’t get any output that indicates it’s not a 64 bit processor.

How to check if my Operating system is a 64-bit or 32-bit?

Before knowing about this you should know about i386, i486 etc naming convention.

What is difference between i386, i486, i586, and i686 OS?

They are the names given by software industry to some software’s for different Intel architectures. If we say i386, it’s Intel 80386 processor, also known as the i386, or just 386, was a 32-bit microprocessor introduced by Intel in 1985. If I say i486 it’s an Intel 80486, i586 it’s a 80586 and i686 it’s a 80686 processor. In short they are called as x86 family which are of 32 bit processor. And for 64 bit OS you will get x86_64.

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Option 1: check with uname command if your OS is 32 bit or 64 bit.

uname -m

uname -p

Option 2: Check with lscpu command as below.

lscpu | grep -i arch

Option 3: Check with getconf command as shown below

getconf LONG_BIT

Sample output for 64 bit OS:

[email protected]:~$ uname -m
x86_64
[email protected]:~$ uname -p
x86_64
[email protected]:~$ lscpu | grep -i arch
Architecture: x86_64
[email protected]:~$ getconf LONG_BIT
64

Sample output for 32 bit OS

[[email protected] ~]$ uname -m
i686
[[email protected] ~]$ uname -p
i686
[[email protected] ~]$ lscpu | grep -i arch
Architecture: i686
[[email protected] ~]$ getconf LONG_BIT
32

Please let us know if you know any other way to get OS and Processor processing bit details.