systemd.mount(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | AUTOMATIC DEPENDENCIES | FSTAB | OPTIONS | SEE ALSO | NOTES | COLOPHON

SYSTEMD.MOUNT(5)              systemd.mount             SYSTEMD.MOUNT(5)

NAME         top

       systemd.mount - Mount unit configuration

SYNOPSIS         top

       mount.mount

DESCRIPTION         top

       A unit configuration file whose name ends in ".mount" encodes
       information about a file system mount point controlled and
       supervised by systemd.

       This man page lists the configuration options specific to this
       unit type. See systemd.unit(5) for the common options of all unit
       configuration files. The common configuration items are
       configured in the generic [Unit] and [Install] sections. The
       mount specific configuration options are configured in the
       [Mount] section.

       Additional options are listed in systemd.exec(5), which define
       the execution environment the mount(8) program is executed in,
       and in systemd.kill(5), which define the way the processes are
       terminated, and in systemd.resource-control(5), which configure
       resource control settings for the processes of the service.

       Note that the options User= and Group= are not useful for mount
       units. systemd passes two parameters to mount(8); the values of
       What= and Where=. When invoked in this way, mount(8) does not
       read any options from /etc/fstab, and must be run as UID 0.

       Mount units must be named after the mount point directories they
       control. Example: the mount point /home/lennart must be
       configured in a unit file home-lennart.mount. For details about
       the escaping logic used to convert a file system path to a unit
       name, see systemd.unit(5). Note that mount units cannot be
       templated, nor is possible to add multiple names to a mount unit
       by creating additional symlinks to it.

       Optionally, a mount unit may be accompanied by an automount unit,
       to allow on-demand or parallelized mounting. See
       systemd.automount(5).

       Mount points created at runtime (independently of unit files or
       /etc/fstab) will be monitored by systemd and appear like any
       other mount unit in systemd. See /proc/self/mountinfo description
       in proc(5).

       Some file systems have special semantics as API file systems for
       kernel-to-userspace and userspace-to-userspace interfaces. Some
       of them may not be changed via mount units, and cannot be
       disabled. For a longer discussion see API File Systems[1].

       The systemd-mount(1) command allows creating .mount and
       .automount units dynamically and transiently from the command
       line.

AUTOMATIC DEPENDENCIES         top

   Implicit Dependencies
       The following dependencies are implicitly added:

       •   If a mount unit is beneath another mount unit in the file
           system hierarchy, both a requirement dependency and an
           ordering dependency between both units are created
           automatically.

       •   Block device backed file systems automatically gain BindsTo=
           and After= type dependencies on the device unit encapsulating
           the block device (see below).

       •   If traditional file system quota is enabled for a mount unit,
           automatic Wants= and Before= dependencies on
           systemd-quotacheck.service and quotaon.service are added.

       •   Additional implicit dependencies may be added as result of
           execution and resource control parameters as documented in
           systemd.exec(5) and systemd.resource-control(5).

   Default Dependencies
       The following dependencies are added unless
       DefaultDependencies=no is set:

       •   All mount units acquire automatic Before= and Conflicts= on
           umount.target in order to be stopped during shutdown.

       •   Mount units referring to local file systems automatically
           gain an After= dependency on local-fs-pre.target, and a
           Before= dependency on local-fs.target unless nofail mount
           option is set.

       •   Network mount units automatically acquire After= dependencies
           on remote-fs-pre.target, network.target and
           network-online.target, and gain a Before= dependency on
           remote-fs.target unless nofail mount option is set. Towards
           the latter a Wants= unit is added as well.

       Mount units referring to local and network file systems are
       distinguished by their file system type specification. In some
       cases this is not sufficient (for example network block device
       based mounts, such as iSCSI), in which case _netdev may be added
       to the mount option string of the unit, which forces systemd to
       consider the mount unit a network mount.

FSTAB         top

       Mount units may either be configured via unit files, or via
       /etc/fstab (see fstab(5) for details). Mounts listed in
       /etc/fstab will be converted into native units dynamically at
       boot and when the configuration of the system manager is
       reloaded. In general, configuring mount points through /etc/fstab
       is the preferred approach. See systemd-fstab-generator(8) for
       details about the conversion.

       The NFS mount option bg for NFS background mounts as documented
       in nfs(5) is detected by systemd-fstab-generator and the options
       are transformed so that systemd fulfills the job-control
       implications of that option. Specifically systemd-fstab-generator
       acts as though "x-systemd.mount-timeout=infinity,retry=10000" was
       prepended to the option list, and "fg,nofail" was appended.
       Depending on specific requirements, it may be appropriate to
       provide some of these options explicitly, or to make use of the
       "x-systemd.automount" option described below instead of using
       "bg".

       When reading /etc/fstab a few special mount options are
       understood by systemd which influence how dependencies are
       created for mount points. systemd will create a dependency of
       type Wants= or Requires= (see option nofail below), from either
       local-fs.target or remote-fs.target, depending whether the file
       system is local or remote.

       x-systemd.requires=
           Configures a Requires= and an After= dependency between the
           created mount unit and another systemd unit, such as a device
           or mount unit. The argument should be a unit name, or an
           absolute path to a device node or mount point. This option
           may be specified more than once. This option is particularly
           useful for mount point declarations that need an additional
           device to be around (such as an external journal device for
           journal file systems) or an additional mount to be in place
           (such as an overlay file system that merges multiple mount
           points). See After= and Requires= in systemd.unit(5) for
           details.

           Note that this option always applies to the created mount
           unit only regardless whether x-systemd.automount has been
           specified.

       x-systemd.before=, x-systemd.after=
           In the created mount unit, configures a Before= or After=
           dependency on another systemd unit, such as a mount unit. The
           argument should be a unit name or an absolute path to a mount
           point. This option may be specified more than once. This
           option is particularly useful for mount point declarations
           with nofail option that are mounted asynchronously but need
           to be mounted before or after some unit start, for example,
           before local-fs.target unit. See Before= and After= in
           systemd.unit(5) for details.

           Note that these options always apply to the created mount
           unit only regardless whether x-systemd.automount has been
           specified.

       x-systemd.wanted-by=, x-systemd.required-by=
           In the created mount unit, configures a WantedBy= or
           RequiredBy= dependency on another unit. This option may be
           specified more than once. If this is specified, the normal
           automatic dependencies on the created mount unit, e.g.,
           local-fs.target, are not automatically created. See WantedBy=
           and RequiredBy= in systemd.unit(5) for details.

       x-systemd.requires-mounts-for=
           Configures a RequiresMountsFor= dependency between the
           created mount unit and other mount units. The argument must
           be an absolute path. This option may be specified more than
           once. See RequiresMountsFor= in systemd.unit(5) for details.

       x-systemd.device-bound
           The block device backed file system will be upgraded to
           BindsTo= dependency. This option is only useful when mounting
           file systems manually with mount(8) as the default dependency
           in this case is Requires=. This option is already implied by
           entries in /etc/fstab or by mount units.

       x-systemd.automount
           An automount unit will be created for the file system. See
           systemd.automount(5) for details.

       x-systemd.idle-timeout=
           Configures the idle timeout of the automount unit. See
           TimeoutIdleSec= in systemd.automount(5) for details.

       x-systemd.device-timeout=
           Configure how long systemd should wait for a device to show
           up before giving up on an entry from /etc/fstab. Specify a
           time in seconds or explicitly append a unit such as "s",
           "min", "h", "ms".

           Note that this option can only be used in /etc/fstab, and
           will be ignored when part of the Options= setting in a unit
           file.

       x-systemd.mount-timeout=
           Configure how long systemd should wait for the mount command
           to finish before giving up on an entry from /etc/fstab.
           Specify a time in seconds or explicitly append a unit such as
           "s", "min", "h", "ms".

           Note that this option can only be used in /etc/fstab, and
           will be ignored when part of the Options= setting in a unit
           file.

           See TimeoutSec= below for details.

       x-systemd.makefs
           The file system will be initialized on the device. If the
           device is not "empty", i.e. it contains any signature, the
           operation will be skipped. It is hence expected that this
           option remains set even after the device has been
           initialized.

           Note that this option can only be used in /etc/fstab, and
           will be ignored when part of the Options= setting in a unit
           file.

           See systemd-makefs@.service(8).

           wipefs(8) may be used to remove any signatures from a block
           device to force x-systemd.makefs to reinitialize the device.

       x-systemd.growfs
           The file system will be grown to occupy the full block
           device. If the file system is already at maximum size, no
           action will be performed. It is hence expected that this
           option remains set even after the file system has been grown.
           Only certain file system types are supported, see
           systemd-makefs@.service(8) for details.

           Note that this option can only be used in /etc/fstab, and
           will be ignored when part of the Options= setting in a unit
           file.

       x-systemd.rw-only
           If a mount operation fails to mount the file system
           read-write, it normally tries mounting the file system
           read-only instead. This option disables that behaviour, and
           causes the mount to fail immediately instead. This option is
           translated into the ReadWriteOnly= setting in a unit file.

       _netdev
           Normally the file system type is used to determine if a mount
           is a "network mount", i.e. if it should only be started after
           the network is available. Using this option overrides this
           detection and specifies that the mount requires network.

           Network mount units are ordered between remote-fs-pre.target
           and remote-fs.target, instead of local-fs-pre.target and
           local-fs.target. They also pull in network-online.target and
           are ordered after it and network.target.

       noauto, auto
           With noauto, the mount unit will not be added as a dependency
           for local-fs.target or remote-fs.target. This means that it
           will not be mounted automatically during boot, unless it is
           pulled in by some other unit. The auto option has the
           opposite meaning and is the default. Note that the noauto
           option has an effect on the mount unit itself only — if
           x-systemd.automount is used (see above), then the matching
           automount unit will still be pulled in by these targets.

       nofail
           With nofail, this mount will be only wanted, not required, by
           local-fs.target or remote-fs.target. Moreover the mount unit
           is not ordered before these target units. This means that the
           boot will continue without waiting for the mount unit and
           regardless whether the mount point can be mounted
           successfully.

       x-initrd.mount
           An additional filesystem to be mounted in the initramfs. See
           initrd-fs.target description in systemd.special(7).

       If a mount point is configured in both /etc/fstab and a unit file
       that is stored below /usr/, the former will take precedence. If
       the unit file is stored below /etc/, it will take precedence.
       This means: native unit files take precedence over traditional
       configuration files, but this is superseded by the rule that
       configuration in /etc/ will always take precedence over
       configuration in /usr/.

OPTIONS         top

       Mount files must include a [Mount] section, which carries
       information about the file system mount points it supervises. A
       number of options that may be used in this section are shared
       with other unit types. These options are documented in
       systemd.exec(5) and systemd.kill(5). The options specific to the
       [Mount] section of mount units are the following:

       What=
           Takes an absolute path of a device node, file or other
           resource to mount. See mount(8) for details. If this refers
           to a device node, a dependency on the respective device unit
           is automatically created. (See systemd.device(5) for more
           information.) This option is mandatory. Note that the usual
           specifier expansion is applied to this setting, literal
           percent characters should hence be written as "%%". If this
           mount is a bind mount and the specified path does not exist
           yet it is created as directory.

       Where=
           Takes an absolute path of a file or directory for the mount
           point; in particular, the destination cannot be a symbolic
           link. If the mount point does not exist at the time of
           mounting, it is created as directory. This string must be
           reflected in the unit filename. (See above.) This option is
           mandatory.

       Type=
           Takes a string for the file system type. See mount(8) for
           details. This setting is optional.

       Options=
           Mount options to use when mounting. This takes a
           comma-separated list of options. This setting is optional.
           Note that the usual specifier expansion is applied to this
           setting, literal percent characters should hence be written
           as "%%".

       SloppyOptions=
           Takes a boolean argument. If true, parsing of the options
           specified in Options= is relaxed, and unknown mount options
           are tolerated. This corresponds with mount(8)'s -s switch.
           Defaults to off.

       LazyUnmount=
           Takes a boolean argument. If true, detach the filesystem from
           the filesystem hierarchy at time of the unmount operation,
           and clean up all references to the filesystem as soon as they
           are not busy anymore. This corresponds with umount(8)'s -l
           switch. Defaults to off.

       ReadWriteOnly=
           Takes a boolean argument. If false, a mount point that shall
           be mounted read-write but cannot be mounted so is retried to
           be mounted read-only. If true the operation will fail
           immediately after the read-write mount attempt did not
           succeed. This corresponds with mount(8)'s -w switch. Defaults
           to off.

       ForceUnmount=
           Takes a boolean argument. If true, force an unmount (in case
           of an unreachable NFS system). This corresponds with
           umount(8)'s -f switch. Defaults to off.

       DirectoryMode=
           Directories of mount points (and any parent directories) are
           automatically created if needed. This option specifies the
           file system access mode used when creating these directories.
           Takes an access mode in octal notation. Defaults to 0755.

       TimeoutSec=
           Configures the time to wait for the mount command to finish.
           If a command does not exit within the configured time, the
           mount will be considered failed and be shut down again. All
           commands still running will be terminated forcibly via
           SIGTERM, and after another delay of this time with SIGKILL.
           (See KillMode= in systemd.kill(5).) Takes a unit-less value
           in seconds, or a time span value such as "5min 20s". Pass 0
           to disable the timeout logic. The default value is set from
           DefaultTimeoutStartSec= option in systemd-system.conf(5).

       Check systemd.exec(5) and systemd.kill(5) for more settings.

SEE ALSO         top

       systemd(1), systemctl(1), systemd-system.conf(5),
       systemd.unit(5), systemd.exec(5), systemd.kill(5),
       systemd.resource-control(5), systemd.service(5),
       systemd.device(5), proc(5), mount(8), systemd-fstab-generator(8),
       systemd.directives(7), systemd-mount(1)

NOTES         top

        1. API File Systems
           https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
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       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                             SYSTEMD.MOUNT(5)

Pages that refer to this page: systemd(1)systemd-mount(1)crypttab(5)systemd.automount(5)systemd.exec(5)systemd.kill(5)systemd.resource-control(5)systemd.swap(5)systemd.unit(5)veritytab(5)systemd.syntax(7)systemd-fstab-generator(8)systemd-gpt-auto-generator(8)systemd-makefs@.service(8)