Apart from:

• lsb_release -a and

• cat /etc/*release ,

you can also see the version in the GNOME System Monitor (press Alt + F2, type gnome-system-monitor, and hit Enter):

Another way, from 2 starting points:

1. From the web browser’s address bar: ghelp:about-ubuntu
2. Run this command (Alt + F2): gnome-help ghelp:about-ubuntu

Both of them have the same effect as using the Main menu > System > About Ubuntu. They open the “Display application and GNOME system help” in a page giving the same information such as https://help.ubuntu.com/10.04/about-ubuntu/C/index.html (in the language in which you are using Ubuntu)

The command to find ubuntu version is,

lsb_release -a

or

cat /etc/lsb-release

or

System > About Ubuntu

To find this information graphically, open the system monitor. The information you want is on the first tab:
(NB: You cannot tell what stage of development it is at!)

Also note mine is not saying “development branch”, so the best way to tell what state your system was at when you installed it, is to know what you download :)!

In Ubuntu 11.10 onwards, the version of Ubuntu installed can be found by entering System Settings > System Info (in newer versions like 14.04 LTS, this tab might be called Details instead):

This page will also tell you whether you have the 32- or 64-bit version of Ubuntu installed, as well as what processor and graphics you have, the amount of RAM installed, and your disk capacity.

$ lsb_release -r
Release:        10.04

$ lsb_release -c
Codename:       lucid

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 10.04.2 LTS
Release:        10.04
Codename:       lucid

$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=10.04
DISTRIB_CODENAME=lucid

“LSB” means Linux Standard Base, a joint project of several Linux
distributions. Its goal is to develop and promote a set of
open standards that will increase compatibility among Linux distributions.

Quite a few ways –

On the command line:

1. lsb_release -a ▸ exact release name, version, etc.
2. cat /etc/issue ▸ formal release name
3. cat /etc/issue.net ▸ cleaner version of previous one
4. cat /etc/debian_version ▸ will give you the Debian code name
5. cat /proc/version ▸ will give you quite a lot of information about your kernel, when was it compiled, which GCC version has been used, etc.
6. uname -a ▸ will tell you about your kernel information, plus architecture (i386 ▸ 32 bit, x86_64 ▸ 64 bit)

If you like a GUI more than the command line, the System page on System Monitor gnome-system-monitor application should give you more than enough information. Release name, architecture variant, cores in the system, RAM available, and the space available on the root file system.

You can check it via command line.

1. Open a Terminal by pressing Ctrl+Alt+T.

2. Type:

   lsb_release -a
   

   and press Enter.

3. The Ubuntu version is displayed on the ‘Description:’ line.

For more details, see here.

This works for most of the linux distros.

cat /etc/issue

Run this in a shell.

There are GUI ways of checking but I prefer the Terminal.

To check your Ubuntu version using the command line:

1. Open a Terminal by pressing Ctrl+Alt+T.
2. Type: lsb_release -a and press Enter.

The Ubuntu version is displayed on the ‘Description:‘ line.

References:

Identifying the version of Ubuntu you are using.

This command will also find your installed Ubuntu version,

awk '/^Description: Ubuntu [0-9]/ {print "Ubuntu",$3; exit;}' /usr/share/python-apt/templates/Ubuntu.info

Example:

$ awk '/^Description: Ubuntu [0-9]/ {print "Ubuntu",$3; exit;}' /usr/share/python-apt/templates/Ubuntu.info
Ubuntu 14.04

Ubuntu Touch

If you are using Ubuntu Touch or have the Ubuntu Touch version of System Settings installed, you can find out more about your version information by tapping/clicking the About this phone button near the bottom. The information displayed may vary depending on the device you are using.

If additionally to the version you want to find out your Ubuntu flavor, run the following:

cat /var/log/installer/media-info 

The output should be something like:

Xubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)

If you also want to be sure about your Desktop Environment, type:

echo $XDG_CURRENT_DESKTOP

The output should be something like:

XFCE

lsb_release -d

Description:    Ubuntu 16.04.1 LTS 

uname -r

4.4.0-62-generic

Run the following command.

hostnamectl | grep 'Operating System'

This will display which Ubuntu version You are using.

The command hostnamectl alone will give much more informations like hostname, kernel version, architecture, etc.

• Open terminal: CTRL + ALT + T

Do you want all details regarding the OS version? you can type:

$ lsb_release -a
// Distributor ID: Zorin
   Description:    Zorin OS 16
   Release:        16
   Codename:       focal

Want the description and release?

$ lsb_release -dr
// Description: Zorin OS 16
   Release:     16

Want the release?

$ lsb_release -r
// Release:     16

Want the codename?

$ lsb_release -c
// Codename:    focal