Displaying which GNU/Linux distro we have installed on our computer

Below, all we need to do in order to know what GNU/Linux distribution we have installed on our computer:

In Debian:

cat /etc/debian_version

In RedHat:

cat /etc/redhat-release
Red Hat Linux release 7.3 (Valhalla)

In Ubuntu:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 10.04 LTS
Release:        10.04
Codename:       lucid

In Suse:

cat /etc/SuSE-release
openSUSE 11.2 (X86-64)
VERSION = 11.2

In Solaris:

uname -a
SunOS 5.6

Table of equivalences:
SUN OS Version Is Solaris Version
SunOS 5.4 Solaris 2.4
SunOS 5.5 Solaris 2.5
SunOS 5.5.1 Solaris 2.5.1
SunOS 5.6 Solaris 2.6
SunOS 5.7 Solaris 7
SunOS 5.8 Solaris 8
SunOS 5.9 Solaris 9
SunOS 5.10 Solaris 10

Other options:

cat /etc/*release
cat /etc/issue