Best way to find the OS name and version on a Unix/Linux platform

Mastering OS Identification: Finding Unix/Linux Name and Version

Discover the most effective commands and methods to accurately identify the operating system name and version across various Unix and Linux distributions.

Identifying the operating system name and version is a fundamental task for system administrators, developers, and anyone working with Unix-like systems. Whether you're troubleshooting, installing software, or ensuring compatibility, knowing your OS specifics is crucial. This article explores the most common and reliable methods to retrieve this information, covering a wide range of Linux distributions and Unix variants.

The uname Command: A Universal Starting Point

The uname command is a standard utility available on virtually all Unix and Linux systems. It provides basic system information, including the kernel name, hostname, kernel release, kernel version, and machine hardware name. While it doesn't directly give you the distribution name, it's an excellent first step to understand the underlying kernel.

uname -a

Display all system information using uname

The output of uname -a typically looks like this:

Linux myhostname 5.15.0-76-generic #83~20.04.1-Ubuntu SMP Mon Jun 19 14:19:46 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

From this, you can deduce the kernel name (Linux), hostname (myhostname), kernel release (5.15.0-76-generic), and architecture (x86_64). However, the distribution name (e.g., Ubuntu, CentOS) is not explicitly stated.

Identifying Linux Distribution and Version

For Linux distributions, the most reliable way to find the distribution name and version is by checking specific files in the /etc directory. The os-release file (or its predecessors) has become the de facto standard for this information.

flowchart TD
    A[Start: Need OS Info?] --> B{Is /etc/os-release present?}
    B -- Yes --> C[Read /etc/os-release]
    C --> D[Extract NAME, VERSION_ID, PRETTY_NAME]
    B -- No --> E{Is /etc/lsb-release present?}
    E -- Yes --> F[Read /etc/lsb-release]
    F --> G[Extract DISTRIB_ID, DISTRIB_RELEASE]
    E -- No --> H{Check distribution-specific files?}
    H -- Yes --> I[e.g., /etc/redhat-release, /etc/debian_version]
    H -- No --> J[Fall back to uname -a]
    D --> K[End: OS Info Found]
    G --> K
    I --> K
    J --> K

Decision flow for identifying Linux distribution and version

Using /etc/os-release (Recommended for Modern Linux)

Most modern Linux distributions adhere to the systemd specification, which includes the /etc/os-release file. This file contains distribution identification data and is the most consistent source of information.

cat /etc/os-release

Display content of the os-release file

Example output from Ubuntu:

PRETTY_NAME="Ubuntu 22.04.3 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.3 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
BUILD_ID=20230801
UBUNTU_CODENAME=jammy

This file provides comprehensive details like NAME, VERSION_ID, and PRETTY_NAME, which are exactly what you need.

grep -E '^(NAME|VERSION_ID|PRETTY_NAME)=' /etc/os-release

Extract specific fields from os-release

Using /etc/lsb-release (Older Linux Distributions)

Some older Linux distributions, or those not fully adopting systemd's os-release standard, might use /etc/lsb-release. This file is part of the Linux Standard Base (LSB) specification.

cat /etc/lsb-release

Display content of the lsb-release file

Example output:

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04.6 LTS"

Distribution-Specific Files

Before the widespread adoption of os-release, many distributions had their own unique files for version information. These are still present on some systems and can serve as a fallback.

Red Hat/CentOS/Fedora

cat /etc/redhat-release

or

cat /etc/centos-release

or

cat /etc/fedora-release

Debian

cat /etc/debian_version

SuSE/OpenSUSE

cat /etc/SuSE-release

Identifying Traditional Unix Systems

For traditional Unix systems like Solaris, AIX, or HP-UX, the methods differ slightly, though uname remains a common starting point.

Solaris/illumos

cat /etc/release

or

uname -v

AIX

oslevel -s

or

uname -v

HP-UX

uname -r

or

swlist -l product | grep -i "OS Environment"

FreeBSD

freebsd-version

or

uname -r

A Robust Script for OS Detection

To handle the various possibilities, especially in automated scripts, it's best to create a function or script that checks for these files in a specific order.

#!/bin/bash

get_os_info() {
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        echo "OS Name: ${PRETTY_NAME:-${NAME} ${VERSION_ID}}"
        echo "ID: ${ID}"
        echo "Version ID: ${VERSION_ID}"
    elif [ -f /etc/lsb-release ]; then
        . /etc/lsb-release
        echo "OS Name: ${DISTRIB_DESCRIPTION:-${DISTRIB_ID} ${DISTRIB_RELEASE}}"
        echo "ID: ${DISTRIB_ID}"
        echo "Version ID: ${DISTRIB_RELEASE}"
    elif [ -f /etc/redhat-release ]; then
        echo "OS Name: $(cat /etc/redhat-release)"
        echo "ID: redhat-based"
    elif [ -f /etc/debian_version ]; then
        echo "OS Name: Debian $(cat /etc/debian_version)"
        echo "ID: debian"
    elif [ -f /etc/SuSE-release ]; then
        echo "OS Name: $(cat /etc/SuSE-release | head -n 1)"
        echo "ID: suse-based"
    else
        echo "OS Name: Unknown Linux/Unix"
        echo "Kernel: $(uname -srm)"
    fi
}

get_os_info

A shell script to robustly detect OS name and version

This script prioritizes /etc/os-release, then falls back to lsb-release, and finally checks for distribution-specific files before resorting to uname for generic Unix/Linux identification. This approach provides the most accurate and detailed information available on the system.