My CPU is 32bit or 64bit?

Simply type the following command and if you see lm (Long Mode) in output, you have a 64 bit CPU based system.

$ grep flags /proc/cpuinfo | grep -i lm

$ if `grep flags /proc/cpuinfo | grep -i " lm " > /dev/null`; then echo "32-bit and 64-bit Architecture"; else echo "32-bit Architecture"; fi

CPU Modes:

lm flag means Long mode cpu - 64 bit CPU

Real mode 16 bit CPU

Protected Mode is 32-bit CPU