man `5 os-release`

OS-RELEASE(5) os-release OS-RELEASE(5)

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

SYNOPSIS
/etc/os-release

/usr/lib/os-release

/etc/initrd-release

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

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

The format of os-release is a newline-separated list of
environment-like shell-compatible variable assignments. It is possible
to source the configuration from Bourne 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. (Assignments that do not include these
special characters may be enclosed in quotes too, but this is
optional.) Shell special characters ("$", quotes, backslash, backtick)
must be escaped with backslashes, following shell style. All strings
should be in UTF-8 encoding, and non-printable characters should not be
used. Concatenation of multiple individually quoted strings is not
supported. Lines beginning with "#" are treated 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.

os-release must not contain repeating keys. Nevertheless, readers
should pick the entries later in the file in case of repeats, similarly
to how a shell sourcing the file would. A reader may warn about
repeating entries.

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.

OPTIONS
The following OS identifications parameters may be set using
os-release:

General information identifying the operating system
NAME=
A string identifying the operating system, without a version
component, and suitable for presentation to the user. If not set, a
default of "NAME=Linux" may be used.

Examples: "NAME=Fedora", "NAME="Debian GNU/Linux"".

ID=
A lower-case string (no spaces or other characters outside of 0-9,
a-z, ".", "_" and "-") identifying the operating system, excluding
any version information and suitable for processing by scripts or
usage in generated filenames. If not set, a default of "ID=linux"
may be used. Note that even though this string may not include
characters that require shell quoting, quoting may nevertheless be
used.

Examples: "ID=fedora", "ID=debian".

ID_LIKE=
A space-separated list of operating system identifiers in the same
syntax as the ID= setting. It should list identifiers of operating
systems that are closely related to the local operating system in
regards to packaging and programming interfaces, for example
listing one or more OS identifiers the local OS is a derivative
from. An OS should generally only list other OS identifiers it
itself is a derivative of, and not any OSes that are derived from
it, though symmetric relationships are possible. Build scripts and
similar should check this variable if they need to identify the
local operating system and the value of ID= is not recognized.
Operating systems should be listed in order of how closely the
local operating system relates to the listed ones, starting with
the closest. This field is optional.

Examples: for an operating system with "ID=centos", an assignment
of "ID_LIKE="rhel fedora"" would be appropriate. For an operating
system with "ID=ubuntu", an assignment of "ID_LIKE=debian" is
appropriate.

PRETTY_NAME=
A pretty operating system name in a format suitable for
presentation to the user. May or may not contain a release code
name or OS version of some kind, as suitable. If not set, a default
of "PRETTY_NAME="Linux"" may be used

Example: "PRETTY_NAME="Fedora 17 (Beefy Miracle)"".

CPE_NAME=
A CPE name for the operating system, in URI binding syntax,
following the Common Platform Enumeration Specification[4] as
proposed by the NIST. This field is optional.

Example: "CPE_NAME="cpe:/o:fedoraproject:fedora:17""

VARIANT=
A string identifying a specific variant or edition of the operating
system suitable for presentation to the user. This field may be
used to inform the user that the configuration of this system is
subject to a specific divergent set of rules or default
configuration settings. This field is optional and may not be
implemented on all systems.

Examples: "VARIANT="Server Edition"", "VARIANT="Smart Refrigerator
Edition"".

Note: this field is for display purposes only. The VARIANT_ID field
should be used for making programmatic decisions.

VARIANT_ID=
A lower-case string (no spaces or other characters outside of 0-9,
a-z, ".", "_" and "-"), identifying a specific variant or edition
of the operating system. This may be interpreted by other packages
in order to determine a divergent default configuration. This field
is optional and may not be implemented on all systems.

Examples: "VARIANT_ID=server", "VARIANT_ID=embedded".

Information about the version of the operating system
VERSION=
A string identifying the operating system version, excluding any OS
name information, possibly including a release code name, and
suitable for presentation to the user. This field is optional.

Examples: "VERSION=17", "VERSION="17 (Beefy Miracle)"".

VERSION_ID=
A lower-case string (mostly numeric, no spaces or other characters
outside of 0-9, a-z, ".", "_" and "-") identifying the operating
system version, excluding any OS name information or release code
name, and suitable for processing by scripts or usage in generated
filenames. This field is optional.

Examples: "VERSION_ID=17", "VERSION_ID=11.04".

VERSION_CODENAME=
A lower-case string (no spaces or other characters outside of 0-9,
a-z, ".", "_" and "-") identifying the operating system release
code name, excluding any OS name information or release version,
and suitable for processing by scripts or usage in generated
filenames. This field is optional and may not be implemented on all
systems.

Examples: "VERSION_CODENAME=buster", "VERSION_CODENAME=xenial".

BUILD_ID=
A string uniquely identifying the system image originally used as
the installation base. In most cases, VERSION_ID or
IMAGE_ID+IMAGE_VERSION are updated when the entire system image is
replaced during an update. BUILD_ID may be used in distributions
where the original installation image version is important:
VERSION_ID would change during incremental system updates, but
BUILD_ID would not. This field is optional.

Examples: "BUILD_ID="2013-03-20.3"", "BUILD_ID=201303203".

IMAGE_ID=
A lower-case string (no spaces or other characters outside of 0-9,
a-z, ".", "_" and "-"), identifying a specific image of the
operating system. This is supposed to be used for environments
where OS images are prepared, built, shipped and updated as
comprehensive, consistent OS images. This field is optional and may
not be implemented on all systems, in particularly not on those
that are not managed via images but put together and updated from
individual packages and on the local system.

Examples: "IMAGE_ID=vendorx-cashier-system",
"IMAGE_ID=netbook-image".

IMAGE_VERSION=
A lower-case string (mostly numeric, no spaces or other characters
outside of 0-9, a-z, ".", "_" and "-") identifying the OS image
version. This is supposed to be used together with IMAGE_ID
described above, to discern different versions of the same image.

Examples: "IMAGE_VERSION=33", "IMAGE_VERSION=47.1rc1".

To summarize: if the image updates are built and shipped as
comprehensive units, IMAGE_ID+IMAGE_VERSION is the best fit. Otherwise,
if updates eventually completely replace previously installed contents,
as in a typical binary distribution, VERSION_ID should be used to
identify major releases of the operating system. BUILD_ID may be used
instead or in addition to VERSION_ID when the original system image
version is important.

Presentation information and links
HOME_URL=, DOCUMENTATION_URL=, SUPPORT_URL=, BUG_REPORT_URL=,
PRIVACY_POLICY_URL=
Links to resources on the Internet related to the operating system.
HOME_URL= should refer to the homepage of the operating system, or
alternatively some homepage of the specific version of the
operating system. DOCUMENTATION_URL= should refer to the main
documentation page for this operating system. SUPPORT_URL= should
refer to the main support page for the operating system, if there
is any. This is primarily intended for operating systems which
vendors provide support for. BUG_REPORT_URL= should refer to the
main bug reporting page for the operating system, if there is any.
This is primarily intended for operating systems that rely on
community QA. PRIVACY_POLICY_URL= should refer to the main privacy
policy page for the operating system, if there is any. These
settings are optional, and providing only some of these settings is
common. These URLs are intended to be exposed in "About this
system" UIs behind links with captions such as "About this
Operating System", "Obtain Support", "Report a Bug", or "Privacy
Policy". The values should be in RFC3986 format[5], and should be
"http:" or "https:" URLs, and possibly "mailto:" or "tel:". Only
one URL shall be listed in each setting. If multiple resources need
to be referenced, it is recommended to provide an online landing
page linking all available resources.

Examples: "HOME_URL="https://fedoraproject.org/"",
"BUG_REPORT_URL="https://bugzilla.redhat.com/"".

SUPPORT_END=
The date at which support for this version of the OS ends. (What
exactly "lack of support" means varies between vendors, but
generally users should assume that updates, including security
fixes, will not be provided.) The value is a date in the ISO 8601
format "YYYY-MM-DD", and specifies the first day on which support
is not provided.

For example, "SUPPORT_END=2001-01-01" means that the system was
supported until the end of the last day of the previous millennium.

LOGO=
A string, specifying the name of an icon as defined by
freedesktop.org Icon Theme Specification[6]. This can be used by
graphical applications to display an operating system's or
distributor's logo. This field is optional and may not necessarily
be implemented on all systems.

Examples: "LOGO=fedora-logo", "LOGO=distributor-logo-opensuse"

ANSI_COLOR=
A suggested presentation color when showing the OS name on the
console. This should be specified as string suitable for inclusion
in the ESC [ m ANSI/ECMA-48 escape code for setting graphical
rendition. This field is optional.

Examples: "ANSI_COLOR="0;31"" for red, "ANSI_COLOR="1;34"" for
light blue, or "ANSI_COLOR="0;38;2;60;110;180"" for Fedora blue.

Distribution-level defaults and metadata
DEFAULT_HOSTNAME=
A string specifying the hostname if hostname(5) is not present and
no other configuration source specifies the hostname. Must be
either a single DNS label (a string composed of 7-bit ASCII
lower-case characters and no spaces or dots, limited to the format
allowed for DNS domain name labels), or a sequence of such labels
separated by single dots that forms a valid DNS FQDN. The hostname
must be at most 64 characters, which is a Linux limitation (DNS
allows longer names).

See org.freedesktop.hostname1(5) for a description of how systemd-
hostnamed.service(8) determines the fallback hostname.

ARCHITECTURE=
A string that specifies which CPU architecture the userspace
binaries require. The architecture identifiers are the same as for
ConditionArchitecture= described in systemd.unit(5). The field is
optional and should only be used when just single architecture is
supported. It may provide redundant information when used in a GPT
partition with a GUID type that already encodes the architecture.
If this is not the case, the architecture should be specified in
e.g., an extension image, to prevent an incompatible host from
loading it.

SYSEXT_LEVEL=
A lower-case string (mostly numeric, no spaces or other characters
outside of 0-9, a-z, ".", "_" and "-") identifying the operating
system extensions support level, to indicate which extension images
are supported. See
/usr/lib/extension-release.d/extension-release.IMAGE, initrd[2] and
systemd-sysext(8)) for more information.

Examples: "SYSEXT_LEVEL=2", "SYSEXT_LEVEL=15.14".

SYSEXT_SCOPE=
Takes a space-separated list of one or more of the strings
"system", "initrd" and "portable". This field is only supported in
extension-release.d/ files and indicates what environments the
system extension is applicable to: i.e. to regular systems, to
initrds, or to portable service images. If unspecified,
"SYSEXT_SCOPE=system portable" is implied, i.e. any system
extension without this field is applicable to regular systems and
to portable service environments, but not to initrd environments.

PORTABLE_PREFIXES=
Takes a space-separated list of one or more valid prefix match
strings for the Portable Services[3] logic. This field serves two
purposes: it is informational, identifying portable service images
as such (and thus allowing them to be distinguished from other OS
images, such as bootable system images). It is also used when a
portable service image is attached: the specified or implied
portable service prefix is checked against the list specified here,
to enforce restrictions how images may be attached to a system.

Notes
If you are using this file to determine the OS or a specific version of
it, use the ID and VERSION_ID fields, possibly with ID_LIKE as fallback
for ID. When looking for an OS identification string for presentation
to the user use the PRETTY_NAME field.

Note that operating system vendors may choose not to provide version
information, for example to accommodate for rolling releases. In this
case, VERSION and VERSION_ID may be unset. Applications should not rely
on these fields to be set.

Operating system vendors may extend the file format and introduce new
fields. It is highly recommended to prefix new fields with an OS
specific name in order to avoid name clashes. Applications reading this
file must ignore unknown fields.

Example: "DEBIAN_BTS="debbugs://bugs.debian.org/"".

Container and sandbox runtime managers may make the host's
identification data available to applications by providing the host's
/etc/os-release (if available, otherwise /usr/lib/os-release as a
fallback) as /run/host/os-release.

EXAMPLES
Example 1. os-release file for Fedora Workstation

NAME=Fedora
VERSION="32 (Workstation Edition)"
ID=fedora
VERSION_ID=32
PRETTY_NAME="Fedora 32 (Workstation Edition)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:32"
HOME_URL="https://fedoraproject.org/"
DOCUMENTATION_URL="https://docs.fedoraproject.org/en-US/fedora/f32/system-administrators-guide/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=32
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=32
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Workstation Edition"
VARIANT_ID=workstation

Example 2. extension-release file for an extension for Fedora
Workstation 32

ID=fedora
VERSION_ID=32

Example 3. Reading os-release in sh(1)

#!/bin/sh -eu
# SPDX-License-Identifier: MIT-0

test -e /etc/os-release && os_release='/etc/os-release' || os_release='/usr/lib/os-release'
. "${os_release}"

echo "Running on ${PRETTY_NAME:-Linux}"

if [ "${ID:-linux}" = "debian" ] || [ "${ID_LIKE#*debian*}" != "${ID_LIKE}" ]; then
echo "Looks like Debian!"
fi

Example 4. Reading os-release in python(1) (versions >= 3.10)

#!/usr/bin/python
# SPDX-License-Identifier: MIT-0

import platform
os_release = platform.freedesktop_os_release()

pretty_name = os_release.get('PRETTY_NAME', 'Linux')
print(f'Running on {pretty_name!r}')

if 'fedora' in [os_release.get('ID', 'linux'),
*os_release.get('ID_LIKE', '').split()]:
print('Looks like Fedora!')

See docs for platform.freedesktop_os_release[7] for more details.

Example 5. Reading os-release in python(1) (any version)

#!/usr/bin/python
# SPDX-License-Identifier: MIT-0

import ast
import re
import sys

def read_os_release():
try:
filename = '/etc/os-release'
f = open(filename)
except FileNotFoundError:
filename = '/usr/lib/os-release'
f = open(filename)

for line_number, line in enumerate(f, start=1):
line = line.rstrip()
if not line or line.startswith('#'):
continue
m = re.match(r'([A-Z][A-Z_0-9]+)=(.*)', line)
if m:
name, val = m.groups()
if val and val[0] in '"\'':
val = ast.literal_eval(val)
yield name, val
else:
print(f'{filename}:{line_number}: bad line {line!r}',
file=sys.stderr)

os_release = dict(read_os_release())

pretty_name = os_release.get('PRETTY_NAME', 'Linux')
print(f'Running on {pretty_name!r}')

if 'debian' in [os_release.get('ID', 'linux'),
*os_release.get('ID_LIKE', '').split()]:
print('Looks like Debian!')

Note that the above version that uses the built-in implementation is
preferred in most cases, and the open-coded version here is provided
for reference.

SEE ALSO
systemd(1), lsb_release(1), hostname(5), machine-id(5), machine-info(5)

NOTES
1. Announcement of /etc/os-release
http://0pointer.de/blog/projects/os-release

2. initrd
https://docs.kernel.org/admin-guide/initrd.html

3. Portable Services Documentation
https://systemd.io/PORTABLE_SERVICES

4. Common Platform Enumeration Specification
http://scap.nist.gov/specifications/cpe/

5. RFC3986 format
https://tools.ietf.org/html/rfc3986

6. freedesktop.org Icon Theme Specification
https://standards.freedesktop.org/icon-theme-spec/latest

platform.freedesktop_os_release
https://docs.python.org/3/library/platform.html#platform.freedesktop_os_release

systemd 252 OS-RELEASE(5)

man 5 os-release

man `5 os-release`