Every Linux distribution has not only a version number but also a date up to which the vendor ships security updates. The command to check the system version is usually the first step when deciding whether it is time to move to a new release or there is still time to wait.
Why it matters to know the OS version and its support period
Once official support for a version ends, the distribution stops getting security updates: vulnerabilities found in packages remain unfixed, and over time the repositories may stop serving the old branch entirely. For a server facing the internet, that is a direct risk, not a formality.
Checking the version and its support period takes a couple of terminal commands and does not need access to a control panel — it can be done over SSH on any Linux server.
How to check the version from the terminal in Ubuntu and Debian
The command lsb_release -a prints the distribution name, version number, and release codename, if the lsb-release package is installed. Where it is missing, the version is shown by the file /etc/os-release.
lsb_release -a
cat /etc/os-releaseFor a shorter output, a single VERSION field from the same file works:
grep VERSION= /etc/os-releaseHow the kernel version differs from the distribution version
The command uname -r shows the Linux kernel version, not the distribution version — these are different numbers on their own update cycle. The kernel can be updated more often than the distribution release itself, especially on long-term-support branches.
Confusing these two numbers is a common reason an administrator looks up the support period by the kernel number and does not find it on any release list.
How to check the support end date for a specific version
| Distribution | Where support period is stated | How to check locally |
|---|---|---|
| Ubuntu | the official Ubuntu releases page | ubuntu-support-status --show-all |
| Debian | the official Debian Releases page | cat /etc/debian_version plus the codename from os-release |
| Any systemd-based distribution | the vendor's documentation | hostnamectl, the Operating System line |
| A server with a control panel | the server information section in the panel | the version in the uname and os-release output |
| A container image | the image tag in the registry | cat /etc/os-release inside the container |
What happens after support ends
Package repositories for a version that has gone out of support are usually moved to an archive address or simply stop responding — the apt update command starts returning errors instead of a package list. That is the first symptom noticed in practice, earlier than any announcement about security risk.
The second effect is incompatibility: new versions of application software gradually stop supporting old libraries from the outdated release, and installing a current version of an application requires either compiling from source or updating the system itself.
What to do when the support period is ending
The order of steps as the end of support approaches:
- record the exact version and release codename using the command from the section above;
- check the version against the vendor's official releases page;
- plan the upgrade ahead of time, instead of waiting for the repositories to go dark — the order for Ubuntu is covered in the article on upgrading Ubuntu, for Debian in the article on upgrading the Debian version;
- make a backup before the upgrade — configs, the database, and uploaded files;
- after the upgrade, check whether the hostname and network settings have changed — if needed, the server name can be fixed using the method from the article on changing the hostname on Linux.
Frequently asked questions
How to check the Ubuntu version quickly with one command?
The command lsb_release -a or reading the file /etc/os-release prints the version number and codename in a single call, with no extra packages needed on most current Ubuntu builds.
How does the kernel version differ from the distribution version?
The kernel version shown by uname -r updates on its own schedule and is not the same as the distribution release number. To determine the branch and its support period, the distribution version matters, not the kernel.
What happens if a server is not updated after support ends?
The server keeps running but stops receiving fixes for vulnerabilities, and over time the package repositories themselves may become unavailable. For a server with external access, that is a gradually growing risk, not a one-time problem.
Can the support period be checked without internet access?
Locally the version and release codename can be checked, but the exact support period is held by the distribution vendor and should be checked against the official releases page once network access is available.