Путеводитель по Руководству Linux

  User  |  Syst  |  Libr  |  Device  |  Files  |  Other  |  Admin  |  Head  |



   initrd-release    ( 5 )

идентификация операционной системы (Operating system identification)

Имя (Name)

os-release, initrd-release, extension-release - Operating system identification


Синопсис (Synopsis)

/etc/os-release

/usr/lib/os-release

/etc/initrd-release

/usr/lib/extension-release.d/extension-release.IMAGE


Описание (Description)

The /etc/os-release and /usr/lib/os-release files contain operating system identification data.

The basic file format of os-release is a newline-separated list of environment-like shell-compatible variable assignments. It is possible to source the configuration from shell scripts, however, beyond mere variable assignments, no shell features are supported (this means variable expansion is explicitly not supported), allowing applications to read the file without implementing a shell compatible execution engine. Variable assignment values must be enclosed in double or single quotes if they include spaces, semicolons or other special characters outside of A–Z, a–z, 0–9. Shell special characters ("$", quotes, backslash, backtick) must be escaped with backslashes, following shell style. All strings should be in UTF-8 format, and non-printable characters should not be used. It is not supported to concatenate multiple individually quoted strings. Lines beginning with "#" shall be ignored as comments. Blank lines are permitted and ignored.

The file /etc/os-release takes precedence over /usr/lib/os-release. Applications should check for the former, and exclusively use its data if it exists, and only fall back to /usr/lib/os-release if it is missing. Applications should not read data from both files at the same time. /usr/lib/os-release is the recommended place to store OS release information as part of vendor trees. /etc/os-release should be a relative symlink to /usr/lib/os-release, to provide compatibility with applications only looking at /etc/. A relative symlink instead of an absolute symlink is necessary to avoid breaking the link in a chroot or initrd environment such as dracut.

os-release contains data that is defined by the operating system vendor and should generally not be changed by the administrator.

As this file only encodes names and identifiers it should not be localized.

The /etc/os-release and /usr/lib/os-release files might be symlinks to other files, but it is important that the file is available from earliest boot on, and hence must be located on the root file system.

For a longer rationale for os-release please refer to the Announcement of /etc/os-release[1].

/etc/initrd-release In the initrd[2], /etc/initrd-release plays the same role as os-release in the main system. Additionally, the presence of that file means that the system is in the initrd phase. /etc/os-release should be symlinked to /etc/initrd-release (or vice versa), so programs that only look for /etc/os-release (as described above) work correctly.

The rest of this document that talks about os-release should be understood to apply to initrd-release too.

/usr/lib/extension-release.d/extension-release.IMAGE /usr/lib/extension-release.d/extension-release.IMAGE plays the same role for extension images as os-release for the main system, and follows the syntax and rules as described in the Portable Services Documentation[3]. The purpose of this file is to identify the extension and to allow the operating system to verify that the extension image matches the base OS. This is typically implemented by checking that the ID= options match, and either SYSEXT_LEVEL= exists and matches too, or if it is not present, VERSION_ID= exists and matches. This ensures ABI/API compatibility between the layers and prevents merging of an incompatible image in an overlay.

In the extension-release.IMAGE filename, the IMAGE part must exactly match the file name of the containing image with the suffix removed. In case it is not possible to guarantee that an image file name is stable and doesn't change between the build and the deployment phases, it is possible to relax this check: if exactly one file whose name matches "extension-release.*" is present in this directory, and the file is tagged with a user.extension-release.strict xattr(7) set to the string "0", it will be used instead.

The rest of this document that talks about os-release should be understood to apply to extension-release too.