1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"os-release" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
8 <title>os-release
</title>
9 <productname>systemd
</productname>
13 <refentrytitle>os-release
</refentrytitle>
14 <manvolnum>5</manvolnum>
18 <refname>os-release
</refname>
19 <refname>initrd-release
</refname>
20 <refname>extension-release
</refname>
21 <refpurpose>Operating system identification
</refpurpose>
26 <member><filename>/etc/os-release
</filename></member>
27 <member><filename>/usr/lib/os-release
</filename></member>
28 <member><filename>/etc/initrd-release
</filename></member>
29 <member><filename>/usr/lib/extension-release.d/extension-release.
<replaceable>IMAGE
</replaceable></filename></member>
34 <title>Description
</title>
36 <para>The
<filename>/etc/os-release
</filename> and
37 <filename>/usr/lib/os-release
</filename> files contain operating
38 system identification data.
</para>
40 <para>The format of
<filename>os-release
</filename> is a newline-separated list of
41 environment-like shell-compatible variable assignments. It is possible to source the configuration from
42 Bourne shell scripts, however, beyond mere variable assignments, no shell features are supported (this
43 means variable expansion is explicitly not supported), allowing applications to read the file without
44 implementing a shell compatible execution engine. Variable assignment values must be enclosed in double
45 or single quotes if they include spaces, semicolons or other special characters outside of A–Z, a–z,
46 0–
9. (Assignments that do not include these special characters may be enclosed in quotes too, but this is
47 optional.) Shell special characters (
"$", quotes, backslash, backtick) must be escaped with backslashes,
48 following shell style. All strings should be in UTF-
8 encoding, and non-printable characters should not
49 be used. Concatenation of multiple individually quoted strings is not supported. Lines beginning with
"#"
50 are treated as comments. Blank lines are permitted and ignored.
</para>
52 <para>The file
<filename>/etc/os-release
</filename> takes
53 precedence over
<filename>/usr/lib/os-release
</filename>.
54 Applications should check for the former, and exclusively use its
55 data if it exists, and only fall back to
56 <filename>/usr/lib/os-release
</filename> if it is missing.
57 Applications should not read data from both files at the same
58 time.
<filename>/usr/lib/os-release
</filename> is the recommended
59 place to store OS release information as part of vendor trees.
60 <filename>/etc/os-release
</filename> should be a relative symlink
61 to
<filename>/usr/lib/os-release
</filename>, to provide
62 compatibility with applications only looking at
63 <filename>/etc/
</filename>. A relative symlink instead of an
64 absolute symlink is necessary to avoid breaking the link in a
65 chroot or initrd environment.
</para>
67 <para><filename>os-release
</filename> contains data that is
68 defined by the operating system vendor and should generally not be
69 changed by the administrator.
</para>
71 <para>As this file only encodes names and identifiers it should
72 not be localized.
</para>
74 <para>The
<filename>/etc/os-release
</filename> and
75 <filename>/usr/lib/os-release
</filename> files might be symlinks
76 to other files, but it is important that the file is available
77 from earliest boot on, and hence must be located on the root file
80 <para><filename>os-release
</filename> must not contain repeating keys. Nevertheless, readers should pick
81 the entries later in the file in case of repeats, similarly to how a shell sourcing the file would. A
82 reader may warn about repeating entries.
</para>
84 <para>For a longer rationale for
<filename>os-release
</filename>
85 please refer to the
<ulink
86 url=
"https://0pointer.de/blog/projects/os-release">Announcement of
<filename>/etc/os-release
</filename></ulink>.
</para>
89 <title><filename>/etc/initrd-release
</filename></title>
92 url=
"https://docs.kernel.org/admin-guide/initrd.html">initrd
</ulink>,
93 <filename>/etc/initrd-release
</filename> plays the same role as
<filename>os-release
</filename> in the
94 main system. Additionally, the presence of that file means that the system is in the initrd phase.
95 <filename>/etc/os-release
</filename> should be symlinked to
<filename>/etc/initrd-release
</filename>
96 (or vice versa), so programs that only look for
<filename>/etc/os-release
</filename> (as described
97 above) work correctly.
</para>
99 <para>The rest of this document that talks about
<filename>os-release
</filename> should be understood
100 to apply to
<filename>initrd-release
</filename> too.
</para>
104 <title><filename>/usr/lib/extension-release.d/extension-release.
<replaceable>IMAGE
</replaceable></filename></title>
106 <para><filename>/usr/lib/extension-release.d/extension-release.
<replaceable>IMAGE
</replaceable></filename>
107 plays the same role for extension images as
<filename>os-release
</filename> for the main system, and
108 follows the syntax and rules as described in the
<ulink
109 url=
"https://systemd.io/PORTABLE_SERVICES">Portable Services
</ulink> page. The purpose of this
110 file is to identify the extension and to allow the operating system to verify that the extension image
111 matches the base OS. This is typically implemented by checking that the
<varname>ID=
</varname> options
112 match, and either
<varname>SYSEXT_LEVEL=
</varname> exists and matches too, or if it is not present,
113 <varname>VERSION_ID=
</varname> exists and matches. This ensures ABI/API compatibility between the
114 layers and prevents merging of an incompatible image in an overlay.
</para>
116 <para>In order to identify the extension image itself, the same fields defined below can be added to the
117 <filename>extension-release
</filename> file with a
<varname>SYSEXT_
</varname> prefix (to disambiguate
118 from fields used to match on the base image). E.g.:
<varname>SYSEXT_ID=myext
</varname>,
119 <varname>SYSEXT_VERSION_ID=
1.2.3</varname>.
</para>
121 <para>In the
<filename>extension-release.
<replaceable>IMAGE
</replaceable></filename> filename, the
122 <replaceable>IMAGE
</replaceable> part must exactly match the file name of the containing image with the
123 suffix removed. In case it is not possible to guarantee that an image file name is stable and doesn't
124 change between the build and the deployment phases, it is possible to relax this check: if exactly one
125 file whose name matches
<literal><filename>extension-release.*
</filename></literal> is present in this
126 directory, and the file is tagged with a
<varname>user.extension-release.strict
</varname>
127 <citerefentry project='man-pages'
><refentrytitle>xattr
</refentrytitle><manvolnum>7</manvolnum></citerefentry> set to the
128 string
<literal>0</literal>, it will be used instead.
</para>
130 <para>The rest of this document that talks about
<filename>os-release
</filename> should be understood
131 to apply to
<filename>extension-release
</filename> too.
</para>
136 <title>Options
</title>
138 <para>The following OS identifications parameters may be set using
139 <filename>os-release
</filename>:
</para>
142 <title>General information identifying the operating system
</title>
144 <variablelist class='environment-variables'
>
146 <term><varname>NAME=
</varname></term>
148 <listitem><para>A string identifying the operating system, without a version component, and
149 suitable for presentation to the user. If not set, a default of
<literal>NAME=Linux
</literal> may
152 <para>Examples:
<literal>NAME=Fedora
</literal>,
<literal>NAME=
"Debian GNU/Linux"</literal>.
157 <term><varname>ID=
</varname></term>
159 <listitem><para>A lower-case string (no spaces or other characters outside of
0–
9, a–z,
".",
"_"
160 and
"-") identifying the operating system, excluding any version information and suitable for
161 processing by scripts or usage in generated filenames. If not set, a default of
162 <literal>ID=linux
</literal> may be used. Note that even though this string may not include
163 characters that require shell quoting, quoting may nevertheless be used.
</para>
165 <para>Examples:
<literal>ID=fedora
</literal>,
<literal>ID=debian
</literal>.
</para></listitem>
169 <term><varname>ID_LIKE=
</varname></term>
171 <listitem><para>A space-separated list of operating system identifiers in the same syntax as the
172 <varname>ID=
</varname> setting. It should list identifiers of operating systems that are closely
173 related to the local operating system in regards to packaging and programming interfaces, for
174 example listing one or more OS identifiers the local OS is a derivative from. An OS should
175 generally only list other OS identifiers it itself is a derivative of, and not any OSes that are
176 derived from it, though symmetric relationships are possible. Build scripts and similar should
177 check this variable if they need to identify the local operating system and the value of
178 <varname>ID=
</varname> is not recognized. Operating systems should be listed in order of how
179 closely the local operating system relates to the listed ones, starting with the closest. This
180 field is optional.
</para>
182 <para>Examples: for an operating system with
<literal>ID=centos
</literal>, an assignment of
183 <literal>ID_LIKE=
"rhel fedora"</literal> would be appropriate. For an operating system with
184 <literal>ID=ubuntu
</literal>, an assignment of
<literal>ID_LIKE=debian
</literal> is appropriate.
189 <term><varname>PRETTY_NAME=
</varname></term>
191 <listitem><para>A pretty operating system name in a format suitable for presentation to the
192 user. May or may not contain a release code name or OS version of some kind, as suitable. If not
193 set, a default of
<literal>PRETTY_NAME=
"Linux"</literal> may be used
</para>
195 <para>Example:
<literal>PRETTY_NAME=
"Fedora 17 (Beefy Miracle)"</literal>.
</para></listitem>
199 <term><varname>CPE_NAME=
</varname></term>
201 <listitem><para>A CPE name for the operating system, in URI binding syntax, following the
<ulink
202 url=
"http://scap.nist.gov/specifications/cpe/">Common Platform Enumeration Specification
</ulink> as
203 proposed by the NIST. This field is optional.
</para>
205 <para>Example:
<literal>CPE_NAME=
"cpe:/o:fedoraproject:fedora:17"</literal></para></listitem>
209 <term><varname>VARIANT=
</varname></term>
211 <listitem><para>A string identifying a specific variant or edition of the operating system suitable
212 for presentation to the user. This field may be used to inform the user that the configuration of
213 this system is subject to a specific divergent set of rules or default configuration settings. This
214 field is optional and may not be implemented on all systems.
</para>
216 <para>Examples:
<literal>VARIANT=
"Server Edition"</literal>,
<literal>VARIANT=
"Smart Refrigerator
217 Edition"</literal>.
</para>
219 <para>Note: this field is for display purposes only. The
<varname>VARIANT_ID
</varname> field should
220 be used for making programmatic decisions.
</para>
222 <xi:include href=
"version-info.xml" xpointer=
"v220"/></listitem>
226 <term><varname>VARIANT_ID=
</varname></term>
228 <listitem><para>A lower-case string (no spaces or other characters outside of
0–
9, a–z,
".",
"_" and
229 "-"), identifying a specific variant or edition of the operating system. This may be interpreted by
230 other packages in order to determine a divergent default configuration. This field is optional and
231 may not be implemented on all systems.
</para>
233 <para>Examples:
<literal>VARIANT_ID=server
</literal>,
<literal>VARIANT_ID=embedded
</literal>.
236 <xi:include href=
"version-info.xml" xpointer=
"v220"/></listitem>
242 <title>Information about the version of the operating system
</title>
244 <variablelist class='environment-variables'
>
246 <term><varname>VERSION=
</varname></term>
248 <listitem><para>A string identifying the operating system version, excluding any OS name
249 information, possibly including a release code name, and suitable for presentation to the
250 user. This field is optional.
</para>
252 <para>Examples:
<literal>VERSION=
17</literal>,
<literal>VERSION=
"17 (Beefy Miracle)"</literal>.
257 <term><varname>VERSION_ID=
</varname></term>
259 <listitem><para>A lower-case string (mostly numeric, no spaces or other characters outside of
0–
9,
260 a–z,
".",
"_" and
"-") identifying the operating system version, excluding any OS name information
261 or release code name, and suitable for processing by scripts or usage in generated filenames. This
262 field is optional.
</para>
264 <para>Examples:
<literal>VERSION_ID=
17</literal>,
<literal>VERSION_ID=
11.04</literal>.
269 <term><varname>VERSION_CODENAME=
</varname></term>
271 <listitem><para>A lower-case string (no spaces or other characters outside of
0–
9, a–z,
".",
"_"
272 and
"-") identifying the operating system release code name, excluding any OS name information or
273 release version, and suitable for processing by scripts or usage in generated filenames. This field
274 is optional and may not be implemented on all systems.
</para>
276 <para>Examples:
<literal>VERSION_CODENAME=buster
</literal>,
277 <literal>VERSION_CODENAME=xenial
</literal>.
</para>
279 <xi:include href=
"version-info.xml" xpointer=
"v231"/></listitem>
283 <term><varname>BUILD_ID=
</varname></term>
285 <listitem><para>A string uniquely identifying the system image originally used as the installation
286 base. In most cases,
<varname>VERSION_ID
</varname> or
287 <varname>IMAGE_ID
</varname>+
<varname>IMAGE_VERSION
</varname> are updated when the entire system
288 image is replaced during an update.
<varname>BUILD_ID
</varname> may be used in distributions where
289 the original installation image version is important:
<varname>VERSION_ID
</varname> would change
290 during incremental system updates, but
<varname>BUILD_ID
</varname> would not. This field is
293 <para>Examples:
<literal>BUILD_ID=
"2013-03-20.3"</literal>,
<literal>BUILD_ID=
201303203</literal>.
296 <xi:include href=
"version-info.xml" xpointer=
"v200"/></listitem>
300 <term><varname>IMAGE_ID=
</varname></term>
302 <listitem><para> A lower-case string (no spaces or other characters outside of
0–
9, a–z,
".",
"_"
303 and
"-"), identifying a specific image of the operating system. This is supposed to be used for
304 environments where OS images are prepared, built, shipped and updated as comprehensive, consistent
305 OS images. This field is optional and may not be implemented on all systems, in particularly not on
306 those that are not managed via images but put together and updated from individual packages and on
307 the local system.
</para>
309 <para>Examples:
<literal>IMAGE_ID=vendorx-cashier-system
</literal>,
310 <literal>IMAGE_ID=netbook-image
</literal>.
</para>
312 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
316 <term><varname>IMAGE_VERSION=
</varname></term>
318 <listitem><para>A lower-case string (mostly numeric, no spaces or other characters outside of
0–
9,
319 a–z,
".",
"_" and
"-") identifying the OS image version. This is supposed to be used together with
320 <varname>IMAGE_ID
</varname> described above, to discern different versions of the same image.
323 <para>Examples:
<literal>IMAGE_VERSION=
33</literal>,
<literal>IMAGE_VERSION=
47.1rc1
</literal>.
326 <xi:include href=
"version-info.xml" xpointer=
"v249"/></listitem>
330 <para>To summarize: if the image updates are built and shipped as comprehensive units,
331 <varname>IMAGE_ID
</varname>+
<varname>IMAGE_VERSION
</varname> is the best fit. Otherwise, if updates
332 eventually completely replace previously installed contents, as in a typical binary distribution,
333 <varname>VERSION_ID
</varname> should be used to identify major releases of the operating system.
334 <varname>BUILD_ID
</varname> may be used instead or in addition to
<varname>VERSION_ID
</varname> when
335 the original system image version is important.
</para>
339 <title>Presentation information and links
</title>
341 <variablelist class='environment-variables'
>
343 <term><varname>HOME_URL=
</varname></term>
344 <term><varname>DOCUMENTATION_URL=
</varname></term>
345 <term><varname>SUPPORT_URL=
</varname></term>
346 <term><varname>BUG_REPORT_URL=
</varname></term>
347 <term><varname>PRIVACY_POLICY_URL=
</varname></term>
349 <listitem><para>Links to resources on the Internet related to the operating system.
350 <varname>HOME_URL=
</varname> should refer to the homepage of the operating system, or alternatively
351 some homepage of the specific version of the operating system.
352 <varname>DOCUMENTATION_URL=
</varname> should refer to the main documentation page for this
353 operating system.
<varname>SUPPORT_URL=
</varname> should refer to the main support page for the
354 operating system, if there is any. This is primarily intended for operating systems which vendors
355 provide support for.
<varname>BUG_REPORT_URL=
</varname> should refer to the main bug reporting page
356 for the operating system, if there is any. This is primarily intended for operating systems that
357 rely on community QA.
<varname>PRIVACY_POLICY_URL=
</varname> should refer to the main privacy
358 policy page for the operating system, if there is any. These settings are optional, and providing
359 only some of these settings is common. These URLs are intended to be exposed in
"About this system"
360 UIs behind links with captions such as
"About this Operating System",
"Obtain Support",
"Report a
361 Bug", or
"Privacy Policy". The values should be in
<ulink
362 url=
"https://tools.ietf.org/html/rfc3986">RFC3986 format
</ulink>, and should be
363 <literal>http:
</literal> or
<literal>https:
</literal> URLs, and possibly
<literal>mailto:
</literal>
364 or
<literal>tel:
</literal>. Only one URL shall be listed in each setting. If multiple resources
365 need to be referenced, it is recommended to provide an online landing page linking all available
368 <para>Examples:
<literal>HOME_URL=
"https://fedoraproject.org/"</literal>,
369 <literal>BUG_REPORT_URL=
"https://bugzilla.redhat.com/"</literal>.
</para></listitem>
373 <term><varname>SUPPORT_END=
</varname></term>
375 <listitem><para>The date at which support for this version of the OS ends. (What exactly
"lack of
376 support" means varies between vendors, but generally users should assume that updates, including
377 security fixes, will not be provided.) The value is a date in the ISO
8601 format
378 <literal>YYYY-MM-DD
</literal>, and specifies the first day on which support
<emphasis>is
379 not
</emphasis> provided.
</para>
381 <para>For example,
<literal>SUPPORT_END=
2001-
01-
01</literal> means that the system was supported
382 until the end of the last day of the previous millennium.
</para>
384 <xi:include href=
"version-info.xml" xpointer=
"v252"/></listitem>
388 <term><varname>LOGO=
</varname></term>
390 <listitem><para>A string, specifying the name of an icon as defined by
<ulink
391 url=
"https://standards.freedesktop.org/icon-theme-spec/latest">freedesktop.org Icon Theme
392 Specification
</ulink>. This can be used by graphical applications to display an operating system's
393 or distributor's logo. This field is optional and may not necessarily be implemented on all
396 <para>Examples:
<literal>LOGO=fedora-logo
</literal>,
<literal>LOGO=distributor-logo-opensuse
</literal>
399 <xi:include href=
"version-info.xml" xpointer=
"v240"/></listitem>
403 <term><varname>ANSI_COLOR=
</varname></term>
405 <listitem><para>A suggested presentation color when showing the OS name on the console. This should
406 be specified as string suitable for inclusion in the ESC [ m ANSI/ECMA-
48 escape code for setting
407 graphical rendition. This field is optional.
</para>
409 <para>Examples:
<literal>ANSI_COLOR=
"0;31"</literal> for red,
<literal>ANSI_COLOR=
"1;34"</literal>
410 for light blue, or
<literal>ANSI_COLOR=
"0;38;2;60;110;180"</literal> for Fedora blue.
415 <term><varname>VENDOR_NAME=
</varname></term>
417 <listitem><para>The name of the OS vendor. This is the name of the organization or company which
418 produces the OS. This field is optional.
</para>
420 <para>This name is intended to be exposed in
"About this system" UIs or software update UIs when
421 needed to distinguish the OS vendor from the OS itself. It is intended to be human readable.
</para>
423 <para>Examples:
<literal>VENDOR_NAME=
"Fedora Project"</literal> for Fedora Linux,
424 <literal>VENDOR_NAME=
"Canonical"</literal> for Ubuntu.
</para>
426 <xi:include href=
"version-info.xml" xpointer=
"v254"/></listitem>
430 <term><varname>VENDOR_URL=
</varname></term>
432 <listitem><para>The homepage of the OS vendor. This field is optional. The
433 <varname>VENDOR_NAME=
</varname> field should be set if this one is, although clients must be
434 robust against either field not being set.
</para>
436 <para>The value should be in
<ulink
437 url=
"https://tools.ietf.org/html/rfc3986">RFC3986 format
</ulink>, and should be
438 <literal>http:
</literal> or
<literal>https:
</literal> URLs. Only one URL shall be listed in the
441 <para>Examples:
<literal>VENDOR_URL=
"https://fedoraproject.org/"</literal>,
442 <literal>VENDOR_URL=
"https://canonical.com/"</literal>.
</para>
444 <xi:include href=
"version-info.xml" xpointer=
"v254"/></listitem>
450 <title>Distribution-level defaults and metadata
</title>
452 <variablelist class='environment-variables'
>
454 <term><varname>DEFAULT_HOSTNAME=
</varname></term>
456 <listitem><para>A string specifying the hostname if
457 <citerefentry><refentrytitle>hostname
</refentrytitle><manvolnum>5</manvolnum></citerefentry> is not
458 present and no other configuration source specifies the hostname. Must be either a single DNS label
459 (a string composed of
7-bit ASCII lower-case characters and no spaces or dots, limited to the
460 format allowed for DNS domain name labels), or a sequence of such labels separated by single dots
461 that forms a valid DNS FQDN. The hostname must be at most
64 characters, which is a Linux
462 limitation (DNS allows longer names).
</para>
464 <para>See
<citerefentry><refentrytitle>org.freedesktop.hostname1
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
465 for a description of how
466 <citerefentry><refentrytitle>systemd-hostnamed.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
467 determines the fallback hostname.
</para>
469 <xi:include href=
"version-info.xml" xpointer=
"v248"/></listitem>
473 <term><varname>ARCHITECTURE=
</varname></term>
474 <listitem><para>A string that specifies which CPU architecture the userspace binaries require.
475 The architecture identifiers are the same as for
<varname>ConditionArchitecture=
</varname>
476 described in
<citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
477 The field is optional and should only be used when just single architecture is supported.
478 It may provide redundant information when used in a GPT partition with a GUID type that already
479 encodes the architecture. If this is not the case, the architecture should be specified in
480 e.g., an extension image, to prevent an incompatible host from loading it.
483 <xi:include href=
"version-info.xml" xpointer=
"v252"/></listitem>
487 <term><varname>SYSEXT_LEVEL=
</varname></term>
489 <listitem><para>A lower-case string (mostly numeric, no spaces or other characters outside of
0–
9,
490 a–z,
".",
"_" and
"-") identifying the operating system extensions support level, to indicate which
491 extension images are supported. See
<filename>/usr/lib/extension-release.d/extension-release.
<replaceable>IMAGE
</replaceable></filename>,
492 <ulink url=
"https://docs.kernel.org/admin-guide/initrd.html">initrd
</ulink> and
493 <citerefentry><refentrytitle>systemd-sysext
</refentrytitle><manvolnum>8</manvolnum></citerefentry>)
494 for more information.
</para>
496 <para>Examples:
<literal>SYSEXT_LEVEL=
2</literal>,
<literal>SYSEXT_LEVEL=
15.14</literal>.
499 <xi:include href=
"version-info.xml" xpointer=
"v248"/></listitem>
503 <term><varname>CONFEXT_LEVEL=
</varname></term>
505 <listitem><para>Semantically the same as
<varname>SYSEXT_LEVEL=
</varname> but for confext images.
506 See
<filename>/etc/extension-release.d/extension-release.
<replaceable>IMAGE
</replaceable></filename>
507 for more information.
</para>
509 <para>Examples:
<literal>CONFEXT_LEVEL=
2</literal>,
<literal>CONFEXT_LEVEL=
15.14</literal>.
512 <xi:include href=
"version-info.xml" xpointer=
"v254"/></listitem>
516 <term><varname>SYSEXT_SCOPE=
</varname></term>
517 <listitem><para>Takes a space-separated list of one or more of the strings
518 <literal>system
</literal>,
<literal>initrd
</literal> and
<literal>portable
</literal>. This field is
519 only supported in
<filename>extension-release.d/
</filename> files and indicates what environments
520 the system extension is applicable to: i.e. to regular systems, to initrds, or to portable service
521 images. If unspecified,
<literal>SYSEXT_SCOPE=system portable
</literal> is implied, i.e. any system
522 extension without this field is applicable to regular systems and to portable service environments,
523 but not to initrd environments.
</para>
525 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
529 <term><varname>CONFEXT_SCOPE=
</varname></term>
531 <listitem><para>Semantically the same as
<varname>SYSEXT_SCOPE=
</varname> but for confext images.
</para>
533 <xi:include href=
"version-info.xml" xpointer=
"v254"/></listitem>
537 <term><varname>PORTABLE_PREFIXES=
</varname></term>
538 <listitem><para>Takes a space-separated list of one or more valid prefix match strings for the
539 <ulink url=
"https://systemd.io/PORTABLE_SERVICES">Portable Services
</ulink> logic.
540 This field serves two purposes: it is informational, identifying portable service images as such
541 (and thus allowing them to be distinguished from other OS images, such as bootable system images).
542 It is also used when a portable service image is attached: the specified or implied portable
543 service prefix is checked against the list specified here, to enforce restrictions how images may
544 be attached to a system.
</para>
546 <xi:include href=
"version-info.xml" xpointer=
"v250"/></listitem>
554 <para>If you are using this file to determine the OS or a specific version of it, use the
555 <varname>ID
</varname> and
<varname>VERSION_ID
</varname> fields, possibly with
556 <varname>ID_LIKE
</varname> as fallback for
<varname>ID
</varname>. When looking for an OS identification
557 string for presentation to the user use the
<varname>PRETTY_NAME
</varname> field.
</para>
559 <para>Note that operating system vendors may choose not to provide version information, for example to
560 accommodate for rolling releases. In this case,
<varname>VERSION
</varname> and
561 <varname>VERSION_ID
</varname> may be unset. Applications should not rely on these fields to be
564 <para>Operating system vendors may extend the file format and introduce new fields. It is highly
565 recommended to prefix new fields with an OS specific name in order to avoid name clashes. Applications
566 reading this file must ignore unknown fields.
</para>
568 <para>Example:
<literal>DEBIAN_BTS=
"debbugs://bugs.debian.org/"</literal>.
</para>
570 <para>Container and sandbox runtime managers may make the host's identification data available to
571 applications by providing the host's
<filename>/etc/os-release
</filename> (if available, otherwise
572 <filename>/usr/lib/os-release
</filename> as a fallback) as
573 <filename>/run/host/os-release
</filename>.
</para>
578 <title>Examples
</title>
581 <title><filename>os-release
</filename> file for Fedora Workstation
</title>
583 <programlisting>NAME=Fedora
584 VERSION=
"32 (Workstation Edition)"
587 PRETTY_NAME=
"Fedora 32 (Workstation Edition)"
588 ANSI_COLOR=
"0;38;2;60;110;180"
589 LOGO=fedora-logo-icon
590 CPE_NAME=
"cpe:/o:fedoraproject:fedora:32"
591 HOME_URL=
"https://fedoraproject.org/"
592 DOCUMENTATION_URL=
"https://docs.fedoraproject.org/en-US/fedora/f32/system-administrators-guide/"
593 SUPPORT_URL=
"https://fedoraproject.org/wiki/Communicating_and_getting_help"
594 BUG_REPORT_URL=
"https://bugzilla.redhat.com/"
595 REDHAT_BUGZILLA_PRODUCT=
"Fedora"
596 REDHAT_BUGZILLA_PRODUCT_VERSION=
32
597 REDHAT_SUPPORT_PRODUCT=
"Fedora"
598 REDHAT_SUPPORT_PRODUCT_VERSION=
32
599 PRIVACY_POLICY_URL=
"https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
600 VARIANT=
"Workstation Edition"
601 VARIANT_ID=workstation
</programlisting>
605 <title><filename>extension-release
</filename> file for an extension for Fedora Workstation
32</title>
607 <programlisting>ID=fedora
608 VERSION_ID=
32</programlisting>
612 <title>Reading
<filename>os-release
</filename> in
613 <citerefentry project='man-pages'
><refentrytitle>sh
</refentrytitle><manvolnum>1</manvolnum></citerefentry></title>
615 <programlisting><xi:include href=
"check-os-release.sh" parse=
"text" /></programlisting>
619 <title>Reading
<filename>os-release
</filename> in
620 <citerefentry project='die-net'
><refentrytitle>python
</refentrytitle><manvolnum>1</manvolnum></citerefentry> (versions
>=
3.10)
</title>
622 <programlisting><xi:include href=
"check-os-release-simple.py" parse=
"text" /></programlisting>
624 <para>See docs for
<ulink url=
"https://docs.python.org/3/library/platform.html#platform.freedesktop_os_release">
625 <function>platform.freedesktop_os_release
</function></ulink> for more details.
630 <title>Reading
<filename>os-release
</filename> in
631 <citerefentry project='die-net'
><refentrytitle>python
</refentrytitle><manvolnum>1</manvolnum></citerefentry> (any version)
</title>
633 <programlisting><xi:include href=
"check-os-release.py" parse=
"text" /></programlisting>
635 <para>Note that the above version that uses the built-in implementation is preferred
636 in most cases, and the open-coded version here is provided for reference.
</para>
642 <title>See Also
</title>
643 <para><simplelist type=
"inline">
644 <member><citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
645 <member><citerefentry project='die-net'
><refentrytitle>lsb_release
</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
646 <member><citerefentry><refentrytitle>hostname
</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
647 <member><citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
648 <member><citerefentry><refentrytitle>machine-info
</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>