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| Copyright 2012 Lennart Poettering |
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| <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 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></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>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 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> |
| </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> |