If *best* is false, the first non-empty version number in priority order of the examined sources is returned. If *best* is true, the most precise version number out of all examined sources is returned. **Lookup hierarchy:** In all cases, the version number is obtained from the following sources. If *best* is false, this order represents the priority order: the value of the "VERSION_ID" attribute of the os-release file, the value of the "Release" attribute returned by the lsb_release command, the version number parsed from the "<version_id>" field of the first line of the distro release file, the version number parsed from the "PRETTY_NAME" attribute of the os-release file, if it follows the format of the distro release files. the version number parsed from the "Description" attribute returned by the lsb_release command, if it follows the format of the distro release files.
Return the version of the current OS distribution, as a human-readable dstring. If *pretty* is false, the version is returned without codename (e.g. "7.0"). If *pretty* is true, the codename in parenthesis is appended, if the codename is non-empty (e.g. "7.0 (Maipo)"). Some distributions provide version numbers with different precisions in the different sources of distribution information. Examining the different sources in a fixed priority order does not always yield the most precise version (e.g. for Debian 8.2, or CentOS 7.1). The *best* parameter can be used to control the approach for the returned