To verify if a system is 32 bit versus 64 bit you can use the uname command. Below are examples of using the uname command from the CLI on a 32 bit system followed by using the uname command on a 64 bit system.
32 Bit CentOS Linux Server
[root@server ~]# uname -a
64 Bit CentOS Linux Server
As you can see above the 64 bit server will show x86_64 numerous times after the install date and time. The 32 bit system will show i686 and i386 after the install date and time. So it is very easy to verify if a system is 32 bit versus 64 bit using the “uname -a” command from a shell.