http://ubuntuforums.org – Four commands on my pc: $ dpkg -l |grep linux-image Linux kernel image for version 3.4.0 on 32 bit x86 SM It means my Ubuntu kernel is 32 bits? $ uname -a Linux ny 3.4.0-030400-generic #201205210521 SMP Mon May 21 09:22:02 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux $ file /bin/ls /bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2. (Hardware)