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systemd-stable/man/os-release.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<refentry id="os-release">
<refentryinfo>
<title>os-release</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>os-release</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>os-release</refname>
<refpurpose>Operating system identification</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>/etc/os-release</filename></para>
<para><filename>/usr/lib/os-release</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 basic file 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 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.</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>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>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following OS identifications parameters may be set using
<filename>os-release</filename>:</para>
<variablelist>
<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, defaults to
<literal>NAME=Linux</literal>. Example:
<literal>NAME=Fedora</literal> or <literal>NAME="Debian
GNU/Linux"</literal>.</para></listitem>
</varlistentry>
<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. Example:
<literal>VERSION=17</literal> or <literal>VERSION="17 (Beefy
Miracle)"</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, defaults to
<literal>ID=linux</literal>. Example:
<literal>ID=fedora</literal> or
<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. Example: 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>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. Example: <literal>VERSION_ID=17</literal>
or <literal>VERSION_ID=11.04</literal>.</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, defaults to
<literal>PRETTY_NAME="Linux"</literal>. Example:
<literal>PRETTY_NAME="Fedora 17 (Beefy
Miracle)"</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.
Example: <literal>ANSI_COLOR="0;31"</literal> for red, or
<literal>ANSI_COLOR="1;34"</literal> for light
blue.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CPE_NAME=</varname></term>
<listitem><para>A CPE name for the operating system, following
the <ulink url="https://cpe.mitre.org/specification/">Common
Platform Enumeration Specification</ulink> as proposed by the
MITRE Corporation. This field is optional. Example:
<literal>CPE_NAME="cpe:/o:fedoraproject:fedora:17"</literal>
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>HOME_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 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>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 operation 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. Examples:
<literal>HOME_URL="https://fedoraproject.org/"</literal> and
<literal>BUG_REPORT_URL="https://bugzilla.redhat.com/"</literal></para></listitem>
</varlistentry>
<varlistentry>
<term><varname>BUILD_ID=</varname></term>
<listitem><para>A string uniquely identifying the system image
used as the origin for a distribution (it is not updated with
system updates). The field can be identical between different
VERSION_IDs as BUILD_ID is an only a unique identifier to a
specific version. Distributions that release each update as a
new version would only need to use VERSION_ID as each build is
already distinct based on the VERSION_ID. This field is
optional. Example: <literal>BUILD_ID="2013-03-20.3"</literal>
or <literal>BUILD_ID=201303203</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.
Examples:
<literal>VARIANT="Server Edition"</literal>,
<literal>VARIANT="Smart Refrigerator Edition"</literal>
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.
Examples:
<literal>VARIANT_ID=server</literal>,
<literal>VARIANT_ID=embedded</literal>
</para></listitem>
</varlistentry>
</variablelist>
<para>If you are reading this file from C code or a shell script
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. Example:
<literal>DEBIAN_BTS="debbugs://bugs.debian.org/"</literal></para>
</refsect1>
<refsect1>
<title>Example</title>
<programlisting>NAME=Fedora
VERSION="17 (Beefy Miracle)"
ID=fedora
VERSION_ID=17
PRETTY_NAME="Fedora 17 (Beefy Miracle)"
ANSI_COLOR="0;34"
CPE_NAME="cpe:/o:fedoraproject:fedora:17"
HOME_URL="https://fedoraproject.org/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"</programlisting>
</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>