man/systemd.mount.xml

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  23
  24 <refentry id="systemd.mount">
  25   <refentryinfo>
  26     <title>systemd.mount</title>
  27     <productname>systemd</productname>
  28
  29     <authorgroup>
  30       <author>
  31         <contrib>Developer</contrib>
  32         <firstname>Lennart</firstname>
  33         <surname>Poettering</surname>
  34         <email>lennart@poettering.net</email>
  35       </author>
  36     </authorgroup>
  37   </refentryinfo>
  38
  39   <refmeta>
  40     <refentrytitle>systemd.mount</refentrytitle>
  41     <manvolnum>5</manvolnum>
  42   </refmeta>
  43
  44   <refnamediv>
  45     <refname>systemd.mount</refname>
  46     <refpurpose>Mount unit configuration</refpurpose>
  47   </refnamediv>
  48
  49   <refsynopsisdiv>
  50     <para><filename><replaceable>mount</replaceable>.mount</filename></para>
  51   </refsynopsisdiv>
  52
  53   <refsect1>
  54     <title>Description</title>
  55
  56     <para>A unit configuration file whose name ends in
  57     <literal>.mount</literal> encodes information about a file system
  58     mount point controlled and supervised by systemd.</para>
  59
  60     <para>This man page lists the configuration options specific to
  61     this unit type. See
  62     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  63     for the common options of all unit configuration files. The common
  64     configuration items are configured in the generic [Unit] and
  65     [Install] sections. The mount specific configuration options are
  66     configured in the [Mount] section.</para>
  67
  68     <para>Additional options are listed in
  69     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  70     which define the execution environment the
  71     <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  72     binary is executed in, and in
  73     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  74     which define the way the processes are terminated, and in
  75     <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  76     which configure resource control settings for the processes of the
  77     service. Note that the User= and Group= options are not
  78     particularly useful for mount units specifying a
  79     <literal>Type=</literal> option or using configuration not
  80     specified in <filename>/etc/fstab</filename>;
  81     <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  82     will refuse options that are not listed in
  83     <filename>/etc/fstab</filename> if it is not run as UID 0.</para>
  84
  85     <para>Mount units must be named after the mount point directories
  86     they control. Example: the mount point
  87     <filename noindex='true'>/home/lennart</filename> must be
  88     configured in a unit file <filename>home-lennart.mount</filename>.
  89     For details about the escaping logic used to convert a file system
  90     path to a unit name, see
  91     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  92
  93     <para>Optionally, a mount unit may be accompanied by an automount
  94     unit, to allow on-demand or parallelized mounting. See
  95     <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
  96
  97     <para>If a mount point is beneath another mount point in the file
  98     system hierarchy, a dependency between both units is created
  99     automatically.</para>
 100
 101     <para>Mount points created at runtime (independently of unit files
 102     or <filename>/etc/fstab</filename>) will be monitored by systemd
 103     and appear like any other mount unit in systemd. See
 104     <filename>/proc/self/mountinfo</filename> description in
 105     <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 106     </para>
 107
 108     <para>Some file systems have special semantics as API file systems
 109     for kernel-to-userspace and userspace-to-userspace interfaces. Some
 110     of them may not be changed via mount units, and cannot be
 111     disabled. For a longer discussion see <ulink
 112     url="http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems">API
 113     File Systems</ulink>.</para>
 114   </refsect1>
 115
 116   <refsect1>
 117     <title><filename>fstab</filename></title>
 118
 119     <para>Mount units may either be configured via unit files, or via
 120     <filename>/etc/fstab</filename> (see
 121     <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 122     for details). Mounts listed in <filename>/etc/fstab</filename>
 123     will be converted into native units dynamically at boot and when
 124     the configuration of the system manager is reloaded. In general,
 125     configuring mount points through <filename>/etc/fstab</filename>
 126     is the preferred approach. See
 127     <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 128     for details about the conversion.</para>
 129
 130     <para>When reading <filename>/etc/fstab</filename> a few special
 131     mount options are understood by systemd which influence how
 132     dependencies are created for mount points. systemd will create a
 133     dependency of type <option>Wants</option> or
 134     <option>Requires</option> (see option <option>nofail</option>
 135     below), from either <filename>local-fs.target</filename> or
 136     <filename>remote-fs.target</filename>, depending whether the file
 137     system is local or remote.</para>
 138
 139     <variablelist class='fstab-options'>
 140
 141       <varlistentry>
 142         <term><option>x-systemd.requires=</option></term>
 143
 144         <listitem><para>Configures a <varname>Requires=</varname> and
 145         an <varname>After=</varname> dependency between the created
 146         mount unit and another systemd unit, such as a device or mount
 147         unit. The argument should be a unit name, or an absolute path
 148         to a device node or mount point.  This option may be specified
 149         more than once. This option is particularly useful for mount
 150         point declarations that need an additional device to be around
 151         (such as an external journal device for journal file systems)
 152         or an additional mount to be in place (such as an overlay file
 153         system that merges multiple mount points). See
 154         <varname>After=</varname> and <varname>Requires=</varname> in
 155         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 156         for details.</para></listitem>
 157       </varlistentry>
 158
 159       <varlistentry>
 160         <term><option>x-systemd.requires-mounts-for=</option></term>
 161
 162         <listitem><para>Configures a
 163         <varname>RequiresMountsFor=</varname> dependency between the
 164         created mount unit and other mount units. The argument must be
 165         an absolute path. This option may be specified more than once.
 166         See <varname>RequiresMountsFor=</varname> in
 167         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 168         for details.</para></listitem>
 169        </varlistentry>
 170
 171       <varlistentry>
 172         <term><option>x-systemd.automount</option></term>
 173
 174         <listitem><para>An automount unit will be created for the file
 175         system. See
 176         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 177         for details.</para></listitem>
 178       </varlistentry>
 179
 180       <varlistentry>
 181         <term><option>x-systemd.idle-timeout=</option></term>
 182
 183         <listitem><para>Configures the idle timeout of the
 184         automount unit. See <varname>TimeoutIdleSec=</varname> in
 185         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 186         for details.</para></listitem>
 187       </varlistentry>
 188
 189       <varlistentry>
 190         <term><option>x-systemd.device-timeout=</option></term>
 191
 192         <listitem><para>Configure how long systemd should wait for a
 193         device to show up before giving up on an entry from
 194         <filename>/etc/fstab</filename>. Specify a time in seconds or
 195         explicitly append a unit such as <literal>s</literal>,
 196         <literal>min</literal>, <literal>h</literal>,
 197         <literal>ms</literal>.</para>
 198
 199         <para>Note that this option can only be used in
 200         <filename>/etc/fstab</filename>, and will be
 201         ignored when part of the <varname>Options=</varname>
 202         setting in a unit file.</para>
 203         </listitem>
 204       </varlistentry>
 205
 206       <varlistentry>
 207         <term><option>noauto</option></term>
 208         <term><option>auto</option></term>
 209
 210         <listitem><para>With <option>noauto</option>, this mount will
 211         not be added as a dependency for
 212         <filename>local-fs.target</filename> or
 213         <filename>remote-fs.target</filename>. This means that it will
 214         not be mounted automatically during boot, unless it is pulled
 215         in by some other unit. The <option>auto</option> option has the
 216         opposite meaning and is the default.</para>
 217         </listitem>
 218       </varlistentry>
 219
 220       <varlistentry>
 221         <term><option>nofail</option></term>
 222
 223         <listitem><para>With <option>nofail</option>, this mount will
 224         be only wanted, not required, by
 225         <filename>local-fs.target</filename> or
 226         <filename>remote-fs.target</filename>. This means that the
 227         boot will continue even if this mount point is not mounted
 228         successfully.</para>
 229         </listitem>
 230       </varlistentry>
 231
 232       <varlistentry>
 233         <term><option>x-initrd.mount</option></term>
 234
 235         <listitem><para>An additional filesystem to be mounted in the
 236         initramfs. See <filename>initrd-fs.target</filename>
 237         description in
 238         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 239         </para></listitem>
 240       </varlistentry>
 241     </variablelist>
 242
 243     <para>If a mount point is configured in both
 244     <filename>/etc/fstab</filename> and a unit file that is stored
 245     below <filename>/usr</filename>, the former will take precedence.
 246     If the unit file is stored below <filename>/etc</filename>, it
 247     will take precedence. This means: native unit files take
 248     precedence over traditional configuration files, but this is
 249     superseded by the rule that configuration in
 250     <filename>/etc</filename> will always take precedence over
 251     configuration in <filename>/usr</filename>.</para>
 252   </refsect1>
 253
 254   <refsect1>
 255     <title>Options</title>
 256
 257     <para>Mount files must include a [Mount] section, which carries
 258     information about the file system mount points it supervises. A
 259     number of options that may be used in this section are shared with
 260     other unit types. These options are documented in
 261     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 262     and
 263     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 264     The options specific to the [Mount] section of mount units are the
 265     following:</para>
 266
 267     <variablelist class='unit-directives'>
 268
 269       <varlistentry>
 270         <term><varname>What=</varname></term>
 271         <listitem><para>Takes an absolute path of a device node, file
 272         or other resource to mount. See
 273         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 274         for details. If this refers to a device node, a dependency on
 275         the respective device unit is automatically created. (See
 276         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 277         for more information.) This option is
 278         mandatory.</para></listitem>
 279       </varlistentry>
 280
 281       <varlistentry>
 282         <term><varname>Where=</varname></term>
 283         <listitem><para>Takes an absolute path of a directory of the
 284         mount point. If the mount point does not exist at the time of
 285         mounting, it is created. This string must be reflected in the
 286         unit filename. (See above.) This option is
 287         mandatory.</para></listitem>
 288       </varlistentry>
 289
 290       <varlistentry>
 291         <term><varname>Type=</varname></term>
 292         <listitem><para>Takes a string for the file system type. See
 293         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 294         for details. This setting is optional.</para></listitem>
 295       </varlistentry>
 296
 297       <varlistentry>
 298         <term><varname>Options=</varname></term>
 299
 300         <listitem><para>Mount options to use when mounting. This takes
 301         a comma-separated list of options. This setting is
 302         optional.</para></listitem>
 303       </varlistentry>
 304
 305       <varlistentry>
 306         <term><varname>SloppyOptions=</varname></term>
 307
 308         <listitem><para>Takes a boolean argument. If true, parsing of
 309         the options specified in <varname>Options=</varname> is
 310         relaxed, and unknown mount options are tolerated. This
 311         corresponds with
 312         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
 313         <parameter>-s</parameter> switch. Defaults to
 314         off.</para></listitem>
 315       </varlistentry>
 316
 317       <varlistentry>
 318         <term><varname>DirectoryMode=</varname></term>
 319         <listitem><para>Directories of mount points (and any parent
 320         directories) are automatically created if needed. This option
 321         specifies the file system access mode used when creating these
 322         directories. Takes an access mode in octal notation. Defaults
 323         to 0755.</para></listitem>
 324       </varlistentry>
 325
 326       <varlistentry>
 327         <term><varname>SmackFileSystemRootLabel=</varname></term>
 328         <listitem><para>Takes a string for the SMACK label.
 329         This option specifies the label to assign the root of the
 330         file system if it lacks the SMACK extended attribute.
 331         Note that this option will be ignored if kernel does not
 332         support the SMACK feature.
 333         See <ulink
 334         url="https://www.kernel.org/doc/Documentation/security/Smack.txt">Smack.txt</ulink>
 335         for details. </para></listitem>
 336       </varlistentry>
 337
 338       <varlistentry>
 339         <term><varname>TimeoutSec=</varname></term>
 340         <listitem><para>Configures the time to wait for the mount
 341         command to finish. If a command does not exit within the
 342         configured time, the mount will be considered failed and be
 343         shut down again. All commands still running will be terminated
 344         forcibly via <constant>SIGTERM</constant>, and after another
 345         delay of this time with <constant>SIGKILL</constant>. (See
 346         <option>KillMode=</option> in
 347         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
 348         Takes a unit-less value in seconds, or a time span value such
 349         as "5min 20s". Pass 0 to disable the timeout logic. The
 350         default value is set from the manager configuration file's
 351         <varname>DefaultTimeoutStart=</varname>
 352         variable.</para></listitem>
 353       </varlistentry>
 354     </variablelist>
 355
 356     <para>Check
 357     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 358     and
 359     <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 360     for more settings.</para>
 361   </refsect1>
 362
 363   <refsect1>
 364       <title>See Also</title>
 365       <para>
 366         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 367         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 368         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 369         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 370         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 371         <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 372         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 373         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 374         <citerefentry project='man-pages'><refentrytitle>proc</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 375         <citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 376         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 377         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 378       </para>
 379   </refsect1>
 380
 381 </refentry>