3-3. Oracle Linux

In Oracle Linux, / etc / oracle-release has been added.

$ ls -l /etc/*release
-rw-r--r--. 1 root root  32 May  5 02:08 /etc/oracle-release
-rw-r--r--. 1 root root 479 May  5 02:08 /etc/os-release
-rw-r--r--. 1 root root  45 May  5 02:08 /etc/redhat-release
lrwxrwxrwx. 1 root root  14 May  5 02:08 /etc/system-release -> oracle-release

What's interesting is the comparison with CentOS. Whereas / etc / redhat-release is a symbolic link on CentOS, it is not a symbolic link on Oracle Linux.

$ cat /etc/oracle-release
Oracle Linux Server release 8.2

$ cat /etc/os-release
NAME="Oracle Linux Server"
VERSION="8.2"
ID="ol"
ID_LIKE="fedora"
VARIANT="Server"
VARIANT_ID="server"
VERSION_ID="8.2"
PLATFORM_ID="platform:el8"
PRETTY_NAME="Oracle Linux Server 8.2"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:8:2:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"

ORACLE_BUGZILLA_PRODUCT="Oracle Linux 8"
ORACLE_BUGZILLA_PRODUCT_VERSION=8.2
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=8.2

Since / etc / redhat-release is not a symbolic link, it is the same as RHEL as follows.

$ cat /etc/redhat-release
Red Hat Enterprise Linux release 8.2 (Ootpa)

Such a specification would be a compatibility measure for programs that check distributions.

For driver packages provided by commercial products and HW vendors, / etc / * -release is often used to determine the type and version of the distribution. By leaving the original / etc / redhat-release, you can misidentify it as RHEL and bypass the check.

Pseudo code for version determination

if /etc/redhat-Is there a release
Version confirmation
else if /etc/centos-Is there a release
Version confirmation

3-4. Amazon Linux 2

Amazon Linux 2 does not have a file like / etc / <distribution name> -release.

$ ls -l /etc/*release
-rw-r--r-- 1 root root 212 Jun 24 21:10 /etc/os-release
-rw-r--r-- 1 root root  31 Jun 24 21:10 /etc/system-release

$ cat /etc/system-release
Amazon Linux release 2 (Karoo)

Amazon Linux is a RHEL-based distribution, but unlike CentOS and Oracle Linux, it's not a pure RHEL-compatible distribution. Therefore, the contents of / etc / os-release are also different from other RHEL distributions.

$ cat /etc/os-release
NAME="Amazon Linux"
VERSION="2"
ID="amzn"
ID_LIKE="centos rhel fedora"
VERSION_ID="2"
PRETTY_NAME="Amazon Linux 2"
ANSI_COLOR="0;33"
CPE_NAME="cpe:2.3:o:amazon:amazon_linux:2"
HOME_URL="https://amazonlinux.com/"

3-5. Ubuntu

On Ubuntu there are the following files: I'm using 20.04 LTS this time, but 18.04 LTS is basically the same.

$ ls -l /etc/*release
-rw-r--r-- 1 root root 102 Apr 15 11:09 /etc/lsb-release
lrwxrwxrwx 1 root root  21 Apr 15 11:09 /etc/os-release -> ../usr/lib/os-release

$ ls -l /etc/*version
-rw-r--r-- 1 root root 13 Dec  5  2019 /etc/debian_version
-rw-r--r-- 1 root root 31 Jul 14 15:46 /etc/ec2_version

$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04 LTS"
VERSION_ID="20.04"
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"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

Ubuntu often uses the / etc / lsb-release and lsb_release -a commands. RHEL distributions also have the lsb_release command, but it is often not installed by default (redhat-lsb-core package).

$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04 LTS"

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04 LTS
Release:        20.04
Codename:       focal

20.04 At LTS
$ cat /etc/debian_version
bullseye/sid

18.04 At LTS
$ cat /etc/debian_version
buster/sid

ec2 seems to be unique to Amazon EC2, but it was also found in Azure VM and Oracle Cloud Infrastructure Compute.

$ cat /etc/ec2_version
Ubuntu 20.04 LTS (Focal Fossa)

3-6. Bonus (sample code)

I think it's better to use sed in practice, but here's a distribution-independent sample code that determines the type and version of a distribution.

#!/bin/bash
FILENAME=/etc/os-release
dist=`grep -e ^NAME= ${FILENAME}`
dist=${dist#*\"}
dist=${dist%*\"}
echo "DIST: " $dist

version=`grep -e ^VERSION_ID= ${FILENAME}`
version=${version#*\"}
version=${version%*\"}
version=${version%*\.*}   #Minor version removed
echo "VER: " $version

Output result

DIST:  Oracle Linux Server
VER:  8

4. Summary

• ** Use / etc / * release to find out the distribution type and version **
• ** You can use / etc / os-release as a file common to all distributions **