<?xml version='1.0'?> <!--*-nxml-*-->

<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"

"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="os-release" xmlns:xi="http://www.w3.org/2001/XInclude">

<refentryinfo>

<title>os-release</title>

<productname>systemd</productname>

</refentryinfo>

<refmeta>

<refentrytitle>os-release</refentrytitle>

<manvolnum>5</manvolnum>

</refmeta>

<refnamediv>

<refname>os-release</refname>

<refname>initrd-release</refname>

<refname>extension-release</refname>

<refpurpose>Operating system identification</refpurpose>

</refnamediv>

<refsynopsisdiv>

<para><filename>/etc/os-release</filename></para>

<para><filename>/usr/lib/os-release</filename></para>

<para><filename>/etc/initrd-release</filename></para>

<para><filename>/usr/lib/extension-release.d/extension-release.<replaceable>IMAGE</replaceable></filename></para>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para>The <filename>/etc/os-release</filename> and

<filename>/usr/lib/os-release</filename> files contain operating

system identification data.</para>

<para>The format of <filename>os-release</filename> 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.</para>

<para>The file <filename>/etc/os-release</filename> takes

precedence over <filename>/usr/lib/os-release</filename>.

Applications should check for the former, and exclusively use its

data if it exists, and only fall back to

<filename>/usr/lib/os-release</filename> if it is missing.

Applications should not read data from both files at the same

time. <filename>/usr/lib/os-release</filename> is the recommended

place to store OS release information as part of vendor trees.

<filename>/etc/os-release</filename> should be a relative symlink

to <filename>/usr/lib/os-release</filename>, to provide

compatibility with applications only looking at

<filename>/etc/</filename>. A relative symlink instead of an

absolute symlink is necessary to avoid breaking the link in a

chroot or initrd environment such as dracut.</para>

<para><filename>os-release</filename> contains data that is

defined by the operating system vendor and should generally not be

changed by the administrator.</para>

<para>As this file only encodes names and identifiers it should

not be localized.</para>

<para>The <filename>/etc/os-release</filename> and

<filename>/usr/lib/os-release</filename> 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.</para>

<para><filename>os-release</filename> 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.</para>

<para>For a longer rationale for <filename>os-release</filename>

please refer to the <ulink

url="http://0pointer.de/blog/projects/os-release">Announcement of <filename>/etc/os-release</filename></ulink>.</para>

<refsect2>

<title><filename>/etc/initrd-release</filename></title>

<para>In the <ulink

url="https://www.kernel.org/doc/html/latest/admin-guide/initrd.html">initrd</ulink>,

<filename>/etc/initrd-release</filename> plays the same role as <filename>os-release</filename> in the

main system. Additionally, the presence of that file means that the system is in the initrd phase.

<filename>/etc/os-release</filename> should be symlinked to <filename>/etc/initrd-release</filename>

(or vice versa), so programs that only look for <filename>/etc/os-release</filename> (as described

above) work correctly.</para>

<para>The rest of this document that talks about <filename>os-release</filename> should be understood

to apply to <filename>initrd-release</filename> too.</para>

</refsect2>

<refsect2>

<title><filename>/usr/lib/extension-release.d/extension-release.<replaceable>IMAGE</replaceable></filename></title>

<para><filename>/usr/lib/extension-release.d/extension-release.<replaceable>IMAGE</replaceable></filename>

plays the same role for extension images as <filename>os-release</filename> for the main system, and

follows the syntax and rules as described in the <ulink

url="https://systemd.io/PORTABLE_SERVICES">Portable Services Documentation</ulink>. 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 <varname>ID=</varname> options

match, and either <varname>SYSEXT_LEVEL=</varname> exists and matches too, or if it is not present,

<varname>VERSION_ID=</varname> exists and matches. This ensures ABI/API compatibility between the

layers and prevents merging of an incompatible image in an overlay.</para>

<para>In the <filename>extension-release.<replaceable>IMAGE</replaceable></filename> filename, the

<replaceable>IMAGE</replaceable> 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 <literal><filename>extension-release.*</filename></literal> is present in this

directory, and the file is tagged with a <varname>user.extension-release.strict</varname>

<citerefentry><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry> set to the

string <literal>0</literal>, it will be used instead.</para>

<para>The rest of this document that talks about <filename>os-release</filename> should be understood

to apply to <filename>extension-release</filename> too.</para>

</refsect2>

</refsect1>

<refsect1>

<title>Options</title>

<para>The following OS identifications parameters may be set using

<filename>os-release</filename>:</para>

<refsect2>

<title>General information identifying the operating system</title>

<variablelist class='environment-variables'>

<varlistentry>

<term><varname>NAME=</varname></term>

<listitem><para>A string identifying the operating system, without a version component, and

suitable for presentation to the user. If not set, a default of <literal>NAME=Linux</literal> may

be used.</para>

<para>Examples: <literal>NAME=Fedora</literal>, <literal>NAME="Debian GNU/Linux"</literal>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>ID=</varname></term>

<listitem><para>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

<literal>ID=linux</literal> may be used. Note that even though this string may not include

characters that require shell quoting, quoting may nevertheless be used.</para>

<para>Examples: <literal>ID=fedora</literal>, <literal>ID=debian</literal>.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>ID_LIKE=</varname></term>

<listitem><para>A space-separated list of operating system identifiers in the same syntax as the

<varname>ID=</varname> 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

<varname>ID=</varname> 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.</para>

<para>Examples: for an operating system with <literal>ID=centos</literal>, an assignment of

<literal>ID_LIKE="rhel fedora"</literal> would be appropriate. For an operating system with

<literal>ID=ubuntu</literal>, an assignment of <literal>ID_LIKE=debian</literal> is appropriate.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>PRETTY_NAME=</varname></term>

<listitem><para>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 <literal>PRETTY_NAME="Linux"</literal> may be used</para>

<para>Example: <literal>PRETTY_NAME="Fedora 17 (Beefy Miracle)"</literal>.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>CPE_NAME=</varname></term>

<listitem><para>A CPE name for the operating system, in URI binding syntax, following the <ulink

url="http://scap.nist.gov/specifications/cpe/">Common Platform Enumeration Specification</ulink> as

proposed by the NIST. This field is optional.</para>

<para>Example: <literal>CPE_NAME="cpe:/o:fedoraproject:fedora:17"</literal></para></listitem>

</varlistentry>

<varlistentry>

<term><varname>VARIANT=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>VARIANT="Server Edition"</literal>, <literal>VARIANT="Smart Refrigerator

Edition"</literal>.</para>

<para>Note: this field is for display purposes only. The <varname>VARIANT_ID</varname> field should

be used for making programmatic decisions.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>VARIANT_ID=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>VARIANT_ID=server</literal>, <literal>VARIANT_ID=embedded</literal>.

</para></listitem>

</varlistentry>

</variablelist>

</refsect2>

<refsect2>

<title>Information about the version of the operating system</title>

<variablelist class='environment-variables'>

<varlistentry>

<term><varname>VERSION=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>VERSION=17</literal>, <literal>VERSION="17 (Beefy Miracle)"</literal>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>VERSION_ID=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>VERSION_ID=17</literal>, <literal>VERSION_ID=11.04</literal>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>VERSION_CODENAME=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>VERSION_CODENAME=buster</literal>,

<literal>VERSION_CODENAME=xenial</literal>.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>BUILD_ID=</varname></term>

<listitem><para>A string uniquely identifying the system image originally used as the installation

base. In most cases, <varname>VERSION_ID</varname> or

<varname>IMAGE_ID</varname>+<varname>IMAGE_VERSION</varname> are updated when the entire system

image is replaced during an update. <varname>BUILD_ID</varname> may be used in distributions where

the original installation image version is important: <varname>VERSION_ID</varname> would change

during incremental system updates, but <varname>BUILD_ID</varname> would not. This field is

optional.</para>

<para>Examples: <literal>BUILD_ID="2013-03-20.3"</literal>, <literal>BUILD_ID=201303203</literal>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>IMAGE_ID=</varname></term>

<listitem><para> 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.</para>

<para>Examples: <literal>IMAGE_ID=vendorx-cashier-system</literal>,

<literal>IMAGE_ID=netbook-image</literal>.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>IMAGE_VERSION=</varname></term>

<listitem><para>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

<varname>IMAGE_ID</varname> described above, to discern different versions of the same image.

</para>

<para>Examples: <literal>IMAGE_VERSION=33</literal>, <literal>IMAGE_VERSION=47.1rc1</literal>.

</para></listitem>

</varlistentry>

</variablelist>

<para>To summarize: if the image updates are built and shipped as comprehensive units,

<varname>IMAGE_ID</varname>+<varname>IMAGE_VERSION</varname> is the best fit. Otherwise, if updates

eventually completely replace previously installed contents, as in a typical binary distribution,

<varname>VERSION_ID</varname> should be used to identify major releases of the operating system.

<varname>BUILD_ID</varname> may be used instead or in addition to <varname>VERSION_ID</varname> when

the original system image version is important.</para>

</refsect2>

<refsect2>

<title>Presentation information and links</title>

<variablelist class='environment-variables'>

<varlistentry>

<term><varname>HOME_URL=</varname></term>

<term><varname>DOCUMENTATION_URL=</varname></term>

<term><varname>SUPPORT_URL=</varname></term>

<term><varname>BUG_REPORT_URL=</varname></term>

<term><varname>PRIVACY_POLICY_URL=</varname></term>

<listitem><para>Links to resources on the Internet related to the operating system.

<varname>HOME_URL=</varname> should refer to the homepage of the operating system, or alternatively

some homepage of the specific version of the operating system.

<varname>DOCUMENTATION_URL=</varname> should refer to the main documentation page for this

operating system. <varname>SUPPORT_URL=</varname> 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. <varname>BUG_REPORT_URL=</varname> 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. <varname>PRIVACY_POLICY_URL=</varname> 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 <ulink

url="https://tools.ietf.org/html/rfc3986">RFC3986 format</ulink>, and should be

<literal>http:</literal> or <literal>https:</literal> URLs, and possibly <literal>mailto:</literal>

or <literal>tel:</literal>. 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.</para>

<para>Examples: <literal>HOME_URL="https://fedoraproject.org/"</literal>,

<literal>BUG_REPORT_URL="https://bugzilla.redhat.com/"</literal>.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>LOGO=</varname></term>

<listitem><para>A string, specifying the name of an icon as defined by <ulink

url="http://standards.freedesktop.org/icon-theme-spec/latest">freedesktop.org Icon Theme

Specification</ulink>. 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.</para>

<para>Examples: <literal>LOGO=fedora-logo</literal>, <literal>LOGO=distributor-logo-opensuse</literal>

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>ANSI_COLOR=</varname></term>

<listitem><para>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.</para>

<para>Examples: <literal>ANSI_COLOR="0;31"</literal> for red, <literal>ANSI_COLOR="1;34"</literal>

for light blue, or <literal>ANSI_COLOR="0;38;2;60;110;180"</literal> for Fedora blue.

</para></listitem>

</varlistentry>

</variablelist>

</refsect2>

<refsect2>

<title>Distribution-level defaults and metadata</title>

<variablelist class='environment-variables'>

<varlistentry>

<term><varname>DEFAULT_HOSTNAME=</varname></term>

<listitem><para>A string specifying the hostname if

<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry> 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).</para>

<para>See <citerefentry><refentrytitle>org.freedesktop.hostname1</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for a description of how

<citerefentry><refentrytitle>systemd-hostnamed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>

determines the fallback hostname.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>SYSEXT_LEVEL=</varname></term>

<listitem><para>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 <filename>/usr/lib/extension-release.d/extension-release.<replaceable>IMAGE</replaceable></filename>,

<ulink url="https://www.kernel.org/doc/html/latest/admin-guide/initrd.html">initrd</ulink> and

<citerefentry><refentrytitle>systemd-sysext</refentrytitle><manvolnum>8</manvolnum></citerefentry>)

for more information.</para>

<para>Examples: <literal>SYSEXT_LEVEL=2</literal>, <literal>SYSEXT_LEVEL=15.14</literal>.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>SYSEXT_SCOPE=</varname></term>

<listitem><para>Takes a space-separated list of one or more of the strings

<literal>system</literal>, <literal>initrd</literal> and <literal>portable</literal>. This field is

only supported in <filename>extension-release.d/</filename> files and indicates what environments

the system extension is applicable to: i.e. to regular systems, to initial RAM filesystems

("initrd") or to portable service images. If unspecified, <literal>SYSEXT_SCOPE=system

portable</literal> 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.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>PORTABLE_PREFIXES=</varname></term>

<listitem><para>Takes a space-separated list of one or more valid prefix match strings for the

<ulink url="https://systemd.io/PORTABLE_SERVICES">Portable Services</ulink> 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). In 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.</para></listitem>

</varlistentry>

</variablelist>

</refsect2>

<refsect2>

<title>Notes</title>

<para>If you are using this file to determine the OS or a specific version of it, use the

<varname>ID</varname> and <varname>VERSION_ID</varname> fields, possibly with

<varname>ID_LIKE</varname> as fallback for <varname>ID</varname>. When looking for an OS identification

string for presentation to the user use the <varname>PRETTY_NAME</varname> field.</para>

<para>Note that operating system vendors may choose not to provide version information, for example to

accommodate for rolling releases. In this case, <varname>VERSION</varname> and

<varname>VERSION_ID</varname> may be unset. Applications should not rely on these fields to be

set.</para>

<para>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.</para>

<para>Example: <literal>DEBIAN_BTS="debbugs://bugs.debian.org/"</literal>.</para>

<para>Container and sandbox runtime managers may make the host's identification data available to

applications by providing the host's <filename>/etc/os-release</filename> (if available, otherwise

<filename>/usr/lib/os-release</filename> as a fallback) as

<filename>/run/host/os-release</filename>.</para>

</refsect2>

</refsect1>

<refsect1>

<title>Examples</title>

<example>

<title><filename>os-release</filename> file for Fedora Workstation</title>

<programlisting>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</programlisting>

</example>

<example>

<title><filename>extension-release</filename> file for an extension for Fedora Workstation 32</title>

<programlisting>ID=fedora

VERSION_ID=32</programlisting>

</example>

<example>

<title>Reading <filename>os-release</filename> in

<citerefentry><refentrytitle>sh</refentrytitle><manvolnum>1</manvolnum></citerefentry></title>

<programlisting><xi:include href="check-os-release.sh" parse="text" /></programlisting>

</example>

<example>

<title>Reading <filename>os-release</filename> in

<citerefentry><refentrytitle>python</refentrytitle><manvolnum>1</manvolnum></citerefentry> (versions &gt;= 3.10)</title>

<programlisting><xi:include href="check-os-release-simple.py" parse="text" /></programlisting>

<para>See docs for <ulink url="https://docs.python.org/3/library/platform.html#platform.freedesktop_os_release">

<function>platform.freedesktop_os_release</function></ulink> for more details.

</para>

</example>

<example>

<title>Reading <filename>os-release</filename> in

<citerefentry><refentrytitle>python</refentrytitle><manvolnum>1</manvolnum></citerefentry> (any version)</title>

<programlisting><xi:include href="check-os-release.py" parse="text" /></programlisting>

<para>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.</para>

</example>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry project='die-net'><refentrytitle>lsb_release</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>hostname</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>