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systemd.mount(5) — systemd — Debian trixie — Debian Manpages
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NAME
SYNOPSIS
DESCRIPTION
AUTOMATIC DEPENDENCIES
FSTAB
OPTIONS
SEE ALSO
NOTES
other versions
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SYSTEMD.MOUNT(5)
systemd.mount
SYSTEMD.MOUNT(5)
NAME
systemd.mount - Mount unit configuration
SYNOPSIS
mount
.mount
DESCRIPTION
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 symlinks to its unit file.
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
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
Requires=
StopPropagatedFrom=
, and
After=
type
dependencies on the device unit encapsulating the block device (see
x-systemd.device-bound=
for details).
•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 one or more mount options
among
nofail
x-systemd.wanted-by=
, and
x-systemd.required-by=
is set. See below for detailed information.
Additionally, an
After=
dependency on swap.target is added
when the file system type is "tmpfs".
•Network mount units automatically acquire
After=
dependencies on remote-fs-pre.target, network.target, plus
After=
and
Wants=
dependencies on network-online.target, and a
Before=
dependency on remote-fs.target, unless one or more mount
options among
nofail
x-systemd.wanted-by=
, and
x-systemd.required-by=
is set.
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
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 to manage mounts
for humans. For tooling, writing mount units should be preferred over
editing /etc/fstab. See
systemd-fstab-generator(8)
for details about
the conversion from /etc/fstab to mount units.
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.
Added in version 220.
x-systemd.wants=
Configures a
Wants=
and an
After=
dependency between the created mount unit and another systemd unit, similar to
the
x-systemd.requires=
option.
Added in version 257.
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.
Added in version 233.
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 default dependencies (see above)
other than umount.target on the created mount unit, e.g. local-fs.target, are
not automatically created. Hence it is likely that some ordering dependencies
need to be set up manually through
x-systemd.before=
and
x-systemd.after=
. See
WantedBy=
and
RequiredBy=
in
systemd.unit(5)
for details.
Added in version 245.
x-systemd.wants-mounts-for=
x-systemd.requires-mounts-for=
Configures a
RequiresMountsFor=
or
WantsMountsFor=
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=
or
WantsMountsFor=
in
systemd.unit(5)
for details.
Added in version 220.
x-systemd.device-bound=
Takes a boolean argument. If true or no argument, a
BindsTo=
dependency on the backing device is set. If false, the mount
unit is not stopped no matter whether the backing device is still present.
This is useful when the file system is backed by volume managers. If not set,
and the mount comes from unit fragments, i.e. generated from /etc/fstab by
systemd-fstab-generator(8)
or loaded from a manually configured mount
unit, a combination of
Requires=
and
StopPropagatedFrom=
dependencies is set on the backing device, otherwise only
Requires=
is
used.
Added in version 233.
x-systemd.automount
An automount unit will be created for the file system.
See
systemd.automount(5)
for details.
Added in version 215.
x-systemd.idle-timeout=
Configures the idle timeout of the automount unit. See
TimeoutIdleSec=
in
systemd.automount(5)
for details.
Added in version 220.
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.
Added in version 215.
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.
Added in version 233.
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.
Added in version 236.
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.
Added in version 236.
x-systemd.pcrfs
Measures file system identity information (mount point,
type, label, UUID, partition label, partition UUID) into PCR 15 after the file
system has been mounted. This ensures the
systemd-pcrfs@.service
(8) or
systemd-pcrfs-root.service services are pulled in by the mount unit.
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. It is also
implied for the root and /usr/ partitions discovered by
systemd-gpt-auto-generator(8)
Added in version 253.
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.
Added in version 246.
_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.
Added in version 235.
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 if
x-systemd.automount
(see above) is used,
neither
auto
nor
noauto
have any effect. The matching
automount unit will be added as a dependency to the appropriate target.
Added in version 215.
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.
Added in version 215.
x-initrd.mount
An additional filesystem to be mounted in the initrd. See
initrd-fs.target description in
systemd.special(7)
. This is both an
indicator to the initrd to mount this partition early and an indicator to the
host to leave the partition mounted until final shutdown. Or in other words,
if this flag is set it is assumed the mount shall be active during the entire
regular runtime of the system, i.e. established before the initrd transitions
into the host all the way until the host transitions to the final shutdown
phase.
Added in version 215.
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
Mount unit files may include [Unit] and [Install] sections, which
are described in
systemd.unit(5)
Mount unit 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)
systemd.kill(5)
and
systemd.resource-control(5)
. The options
specific to the [Mount] section of mount units are the following:
What=
Takes an absolute path or a fstab-style identifier 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 either a
directory or a file. The former is the usual case; the latter is done only if
this mount is a bind mount and the source (
What=
) is not a 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.
If the type is "overlay", and "upperdir=" or
"workdir=" are specified as options and the directories do not
exist, they will be created.
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.
Added in version 215.
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.
Added in version 232.
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.
Added in version 246.
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.
Added in version 232.
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.unit(5)
systemd.exec(5)
, and
systemd.kill(5)
for more settings.
SEE ALSO
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
1.
API File Systems
systemd 257.9
Source file:
systemd.mount.5.en.gz (from
systemd 257.9-1~deb13u1
Source last updated:
2025-09-03T18:38:20Z
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2026-04-11T20:45:26Z
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