When people refer to Linux, they are usually referring to a Linux  distribution. Strictly speaking, Linux is a kernel, the core component  of the operating system that simply put acts just like a bridge between  the software applications and the hardware. A Linux distribution is an  operating system made from a Linux kernel, GNU tools and libraries, and  software collections. Usually, Linux distributions include desktop  environments, package management system, and a set of preinstalled  applications.

Some of the most popular Linux distributions are  Debian, Red Hat, Ubuntu, Arch Linux, Fedora, CentOS, Kali Linux,  OpenSUSE, Linux Mint, and more.

When  you log in to a Linux system for the first time, before doing any work,  it is always a good idea to check what version of Linux is running on  the machine. For example, determining the Linux distribution can help  you figure out what package manager you should use to install new  packages.

In  this tutorial, we’ll show you how to check what Linux distribution and  version is installed on your system using the command line.

Checking Linux Version

There are several different commands that can help you find out the Linux distribution and version is running on the system.

Using lsb_release command

The lsb_release utility displays LSB (Linux Standard Base) information about the Linux  distribution. This command should work on all Linux distributions that  have the lsb-release package installed:

lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 9.5 (stretch)
Release:	9.5
Codename:	stretch

The  Linux distribution and version are shown in the Description line. As  you can see from the output above, I have Debian GNU/Linux 9.5 (stretch)  installed on my system.

Instead  of printing all of the above information, you can display the  description line, which shows your Debian version passing the -d switch.

lsb_release -d

The output should look similar to below:

Description:	Debian GNU/Linux 9.5 (stretch)

If you get “command not found: lsb_release” you can try to identify the Linux version using some of the other methods below.

Using /etc/os-release file

The /etc/os-release file contains operating system identification data, including  information about the distribution. This file is a part of the is part  of the systemd package and all Linux system running systemd should have  this file.

To view the contents of the os-release file, use either cat or less:

cat /etc/os-release

The output should look something like below:

PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

Using /etc/issue file

The /etc/issue file contains a system identification text that is printed before the  login prompt. Usually, this file includes information about the Linux  version:

cat /etc/issue

The output will look something like this:

Debian GNU/Linux 9 \n \l

Using hostnamectl command

hostnamectl utility is part of systemd and is used to query and change the system  hostname. This command also displays the Linux distribution and kernel version.

hostnamectl
  Static hostname: debian9.localdomain
         Icon name: computer-vm
           Chassis: vm
        Machine ID: a92099e30f704d559adb18ebc12ddac4
           Boot ID: 7607cbe605d44f638d6542d4c7b3878e
    Virtualization: qemu
  Operating System: Debian GNU/Linux 9 (stretch)
            Kernel: Linux 4.9.0-8-amd64
      Architecture: x86-64

Using /etc/*release file

If  none of the commands above work for you, then most likely, you are  running a very old and outdated Linux distribution. In this case, you  can use one of the following commands which should print the content of  the distribution release or version file:

cat /etc/*release
cat /etc/*version

You can find more information about the release/version files at this link.

Using uname command

The uname command displays several system information, including the Linux kernel architecture, name, version, and release.

To find out what version of the Linux kernel is running on your system, type the following command:

uname -srm
Linux 4.9.0-8-amd64 x86_64

The output above tells us that the Linux kernel is 64-bit, and its version is “4.9.0-8-amd64”.

Conclusion

In this guide, we have shown you how to find the version of Linux running on your system using the command line.

If  you have a Linux distribution with a desktop environment, you can also  check your distribution and its version from within the graphical  interface.

Feel free to leave a comment if you have any questions.