Two years ago I have described three simple ways to determine whether the processor supports 64-bit instruction set. Today, I will show you how to determine whether any Debian-based operating system is 32-bit or 64-bit.
Print machine architecture using uname command
The most obvious way to determine the answer is to execute uname command to print machine architecture.
$ uname -m
Sample output on 64-bit operating system
x86_64
Sample output on 32-bit operating system
i686
Print machine architecture using arch command
arch utility provides exactly the same information as the above (uname -m) command.
$ arch
Sample output on 64-bit operating system
x86_64
Sample output on 32-bit operating system
i686
Query system configuration variables
This is the simplest and most straightforward solution, which is often overlooked, but it is widely supported on Debian-based operating systems.
$ getconf LONG_BIT
Sample output on 64-bit operating system
64
Sample output on 32-bit operating system
32
Print architecture of packages dpkg installs
This is more indirect way to determine the answer, but an interesting one.
$ dpkg --print-architecture
Sample output on 64-bit operating system
amd64
Sample output on 32-bit operating system
i386