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Identifying Linux distribution

Sometimes I come across a Linux install and don't know what distribution runs on it. This page documents the markers I found that permit identification of distribution including its version.

RPM based distributions

These can typically be identified by the presence of "rpm" command. Most systems will have rpm or apt installed, but not both.

Fedora, RHEL and Centos distributions along with their versions can be quickly gleaned from the output of rpm -qa:

  • Fedora installations will have many packages with .fcXX. in their name, where XX is a number like 20 signifying Fedora release.
  • RHEL and Centos installations will have many packages with .elX suffix, where X is a number like 5 signifying the major version of the release.
  • Centos will have packages with .centos in their names, whereas RHEL is unlikely to have any such packages.

Debian and derivative distributions

These can typically be identified by the presence of "apt" and "dpkg" commands.

Debian and Debian derivatives have a /etc/debian_version file. Stable Debian releases have the release version number in it, like 7.0. Systems running the testing distribution will show the code name of the distribution, like jessie/sid.

Ubuntu is apparently built from Debian testing, thus it has the Debian release it was built from, like jessie/sid, in its /etc/debian_version file. Ubuntu can be easily identified by looking for ubuntu in package versions obtained from dpkg -l.

Ubuntu version can be identified by running lsb_release -a, or checking /etc/lsb-release which has the same information. lsb_release -a works on Debian as well but the corresponding file is /etc/os-release.

Another technique that works on Debian and Ubuntu, per this page, is checking /etc/issue.