Windows and macOS have few maintained versions due to their commercial nature. In contrast, FOSS operating systems like BSD and Linux have hundreds of maintained distros. Only a few Linux distros dominate such as Debian, Ubuntu and Red Hat. Less common Linux distros are commonly based on popular distros.
For certain system management tasks and install scripts it’s useful to programatically identify which major Linux distro family the current OS belongs to. A standard method to detect Linux operating system version is via plaintext /etc/os-release. Prior to this de facto standard, older Linux distros used other files.
The algorithm we use to identify older and newer Linux distros is to first check the file “/etc/os-release” versus known distros. If “/etc/os-release” is not present, the algorithm looks for OS-specific files: