The uname command prints certain system information. With the -a option, it prints all information about the Linux OS.
$ uname -a
The version number in the print-out is the kernel release.
A Linux distribution usually has it own release versions. For example, the Ubuntu distribution may have a release version of 8.04. To see the version of a distribution, run command --
$ lsb_release -a
or just view the file /etc/lsb-release.
There is an interesting directory named /proc. It reveals some system information. Just use the cat command to print them, such as:
$ cat /proc/cpuinfo
$ cat /proc/meminfo
$ cat /proc/version