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-<!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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- Copyright 2012 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
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- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
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- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
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+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="systemd-fstab-generator">
- <refentryinfo>
- <title>systemd-fstab-generator</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>systemd-fstab-generator</refentrytitle>
- <manvolnum>8</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>systemd-fstab-generator</refname>
- <refpurpose>Unit generator for /etc/fstab</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename>/usr/lib/systemd/system-generators/systemd-fstab-generator</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para><filename>systemd-fstab-generator</filename> is
- a generator that translates
- <filename>/etc/fstab</filename> (see
- <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details) into native systemd units early at boot
- and when configuration of the system manager is
- reloaded. This will instantiate mount and swap units
- as necessary.</para>
-
- <para>See
- <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- and
- <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for more information about special
- <filename>/etc/fstab</filename> mount options this
- generator understands.</para>
-
- <para><filename>systemd-fstab-generator</filename>
- implements the <ulink
- url="http://www.freedesktop.org/wiki/Software/systemd/Generators">generator
- specification</ulink>.</para>
- </refsect1>
-
- <refsect1>
- <title>Kernel Command Line</title>
-
- <para><filename>systemd-fstab-generator</filename> understands
- the following kernel command line parameters:</para>
-
- <variablelist class='kernel-commandline-options'>
-
- <varlistentry>
- <term><varname>fstab=</varname></term>
- <term><varname>rd.fstab=</varname></term>
-
- <listitem><para>Takes a boolean
- argument. Defaults to
- <literal>yes</literal>. If
- <literal>no</literal>, causes the
- generator to ignore any mounts or swaps
- configured in
- <filename>/etc/fstab</filename>. <varname>rd.fstab=</varname>
- is honored only by initial RAM disk
- (initrd) while
- <varname>fstab=</varname> is
- honored by both the main system and
- the initrd. </para></listitem>
- </varlistentry>
-
- </variablelist>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>systemd-fstab-generator</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd-fstab-generator</refentrytitle>
+ <manvolnum>8</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd-fstab-generator</refname>
+ <refpurpose>Unit generator for /etc/fstab</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>/usr/lib/systemd/system-generators/systemd-fstab-generator</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><filename>systemd-fstab-generator</filename> is a generator
+ that translates <filename>/etc/fstab</filename> (see
+ <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) into native systemd units early at boot and when
+ configuration of the system manager is reloaded. This will
+ instantiate mount and swap units as necessary.</para>
+
+ <para>The <varname>passno</varname> field is treated like a simple
+ boolean, and the ordering information is discarded. However, if
+ the root file system is checked, it is checked before all the
+ other file systems.</para>
+
+ <para>See
+ <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more information about special <filename>/etc/fstab</filename>
+ mount options this generator understands.</para>
+
+ <para>One special topic is handling of symbolic links. Historical init
+ implementations supported symlinks in <filename>/etc/fstab</filename>.
+ Because mount units will refuse mounts where the target is a symbolic link,
+ this generator will resolve any symlinks as far as possible when processing
+ <filename>/etc/fstab</filename> in order to enhance backwards compatibility.
+ If a symlink target does not exist at the time that this generator runs, it
+ is assumed that the symlink target is the final target of the mount.</para>
+
+ <para><filename>systemd-fstab-generator</filename> implements
+ <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Kernel Command Line</title>
+
+ <para><filename>systemd-fstab-generator</filename> understands the
+ following kernel command line parameters:</para>
+
+ <variablelist class='kernel-commandline-options'>
+
+ <varlistentry>
+ <term><varname>fstab=</varname></term>
+ <term><varname>rd.fstab=</varname></term>
+
+ <listitem><para>Takes a boolean argument. Defaults to
+ <literal>yes</literal>. If <literal>no</literal>, causes the
+ generator to ignore any mounts or swap devices configured in
+ <filename>/etc/fstab</filename>. <varname>rd.fstab=</varname>
+ is honored only by the initial RAM disk (initrd) while
+ <varname>fstab=</varname> is honored by both the main system
+ and the initrd.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>root=</varname></term>
+
+ <listitem><para>Takes the root filesystem to mount in the
+ initrd. <varname>root=</varname> is honored by the
+ initrd.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>rootfstype=</varname></term>
+
+ <listitem><para>Takes the root filesystem type that will be
+ passed to the mount command. <varname>rootfstype=</varname> is
+ honored by the initrd.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>rootflags=</varname></term>
+
+ <listitem><para>Takes the root filesystem mount options to use. <varname>rootflags=</varname> is
+ honored by the initrd.</para>
+
+ <para>Note that unlike most kernel command line options this setting does not override settings made
+ in configuration files (specifically: the mount option string in
+ <filename>/etc/fstab</filename>). See
+ <citerefentry><refentrytitle>systemd-remount-fs.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>mount.usr=</varname></term>
+
+ <listitem><para>Takes the <filename>/usr</filename> filesystem
+ to be mounted by the initrd. If
+ <varname>mount.usrfstype=</varname> or
+ <varname>mount.usrflags=</varname> is set, then
+ <varname>mount.usr=</varname> will default to the value set in
+ <varname>root=</varname>.</para>
+
+ <para>Otherwise, this parameter defaults to the
+ <filename>/usr</filename> entry found in
+ <filename>/etc/fstab</filename> on the root filesystem.</para>
+
+ <para><varname>mount.usr=</varname> is honored by the initrd.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>mount.usrfstype=</varname></term>
+
+ <listitem><para>Takes the <filename>/usr</filename> filesystem
+ type that will be passed to the mount command. If
+ <varname>mount.usr=</varname> or
+ <varname>mount.usrflags=</varname> is set, then
+ <varname>mount.usrfstype=</varname> will default to the value
+ set in <varname>rootfstype=</varname>.</para>
+
+ <para>Otherwise, this value will be read from the
+ <filename>/usr</filename> entry in
+ <filename>/etc/fstab</filename> on the root filesystem.</para>
+
+ <para><varname>mount.usrfstype=</varname> is honored by the
+ initrd.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>mount.usrflags=</varname></term>
+
+ <listitem><para>Takes the <filename>/usr</filename> filesystem
+ mount options to use. If <varname>mount.usr=</varname> or
+ <varname>mount.usrfstype=</varname> is set, then
+ <varname>mount.usrflags=</varname> will default to the value
+ set in <varname>rootflags=</varname>.</para>
+
+ <para>Otherwise, this value will be read from the
+ <filename>/usr</filename> entry in
+ <filename>/etc/fstab</filename> on the root filesystem.</para>
+
+ <para><varname>mount.usrflags=</varname> is honored by the
+ initrd.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.volatile=</varname></term>
+
+ <listitem><para>Controls whether the system shall boot up in volatile mode. Takes a boolean argument or the
+ special value <option>state</option>.</para>
+
+ <para>If false (the default), this generator makes no changes to the mount tree and the system is booted up in
+ normal mode.</para>
+
+ <para>If true the generator ensures
+ <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ is run as part of the initial RAM disk ("initrd"). This service changes the mount table before transitioning to
+ the host system, so that a volatile memory file system (<literal>tmpfs</literal>) is used as root directory,
+ with only <filename>/usr</filename> mounted into it from the configured root file system, in read-only
+ mode. This way the system operates in fully stateless mode, with all configuration and state reset at boot and
+ lost at shutdown, as <filename>/etc</filename> and <filename>/var</filename> will be served from the (initially
+ unpopulated) volatile memory file system.</para>
+
+ <para>If set to <option>state</option> the generator will leave the root directory mount point unaltered,
+ however will mount a <literal>tmpfs</literal> file system to <filename>/var</filename>. In this mode the normal
+ system configuration (i.e. the contents of <literal>/etc</literal>) is in effect (and may be modified during
+ system runtime), however the system state (i.e. the contents of <literal>/var</literal>) is reset at boot and
+ lost at shutdown.</para>
+
+ <para>If this setting is set to <literal>overlay</literal> the root file system is set up as
+ <literal>overlayfs</literal> mount combining the read-only root directory with a writable
+ <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
+ nonetheless with all changes being lost at reboot.</para>
+
+ <para>Note that in none of these modes the root directory, <filename>/etc</filename>, <filename>/var</filename>
+ or any other resources stored in the root file system are physically removed. It's thus safe to boot a system
+ that is normally operated in non-volatile mode temporarily into volatile mode, without losing data.</para>
+
+ <para>Note that with the exception of <literal>overlay</literal> mode, enabling this setting will only work
+ correctly on operating systems that can boot up with only <filename>/usr</filename> mounted, and are able to
+ automatically populate <filename>/etc</filename>, and also <filename>/var</filename> in case of
+ <literal>systemd.volatile=yes</literal>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.swap</varname></term>
+
+ <listitem><para>Takes a boolean argument or enables the option if specified
+ without an argument. If disabled, causes the generator to ignore
+ any swap devices configured in <filename>/etc/fstab</filename>.
+ Defaults to enabled.</para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+ </refsect1>
</refentry>
projects / thirdparty / systemd.git / blobdiff