1SYSTEMD.MOUNT(5) systemd.mount SYSTEMD.MOUNT(5)
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6 systemd.mount - Mount unit configuration
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9 mount.mount
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12 A unit configuration file whose name ends in ".mount" encodes
13 information about a file system mount point controlled and supervised
14 by systemd.
15 This man page lists the configuration options specific to this unit
17 type. See systemd.unit(5) for the common options of all unit
18 configuration files. The common configuration items are configured in
19 the generic [Unit] and [Install] sections. The mount specific
20 configuration options are configured in the [Mount] section.
21 Additional options are listed in systemd.exec(5), which define the
23 execution environment the mount(8) program is executed in, and in
24 systemd.kill(5), which define the way the processes are terminated, and
25 in systemd.resource-control(5), which configure resource control
26 settings for the processes of the service.
27 Note that the options User= and Group= are not useful for mount units.
29 systemd passes two parameters to mount(8); the values of What= and
30 Where=. When invoked in this way, mount(8) does not read any options
31 from /etc/fstab, and must be run as UID 0.
32 Mount units must be named after the mount point directories they
34 control. Example: the mount point /home/lennart must be configured in a
35 unit file home-lennart.mount. For details about the escaping logic used
36 to convert a file system path to a unit name, see systemd.unit(5). Note
37 that mount units cannot be templated, nor is possible to add multiple
38 names to a mount unit by creating additional symlinks to it.
39 Optionally, a mount unit may be accompanied by an automount unit, to
41 allow on-demand or parallelized mounting. See systemd.automount(5).
42 Mount points created at runtime (independently of unit files or
44 /etc/fstab) will be monitored by systemd and appear like any other
45 mount unit in systemd. See /proc/self/mountinfo description in proc(5).
46 Some file systems have special semantics as API file systems for
48 kernel-to-userspace and userspace-to-userspace interfaces. Some of them
49 may not be changed via mount units, and cannot be disabled. For a
50 longer discussion see API File Systems[1].
51 The systemd-mount(1) command allows creating .mount and .automount
53 units dynamically and transiently from the command line.
54
56 Implicit Dependencies
57 The following dependencies are implicitly added:
58 • If a mount unit is beneath another mount unit in the file system
60 hierarchy, both a requirement dependency and an ordering dependency
61 between both units are created automatically.
62 • Block device backed file systems automatically gain BindsTo= and
64 After= type dependencies on the device unit encapsulating the block
65 device (see below).
66 • If traditional file system quota is enabled for a mount unit,
68 automatic Wants= and Before= dependencies on
69 systemd-quotacheck.service and quotaon.service are added.
70 • Additional implicit dependencies may be added as result of
72 execution and resource control parameters as documented in
73 systemd.exec(5) and systemd.resource-control(5).
74 Default Dependencies
76 The following dependencies are added unless DefaultDependencies=no is
77 set:
78 • All mount units acquire automatic Before= and Conflicts= on
80 umount.target in order to be stopped during shutdown.
81 • Mount units referring to local file systems automatically gain an
83 After= dependency on local-fs-pre.target, and a Before= dependency
84 on local-fs.target unless nofail mount option is set.
85 • Network mount units automatically acquire After= dependencies on
87 remote-fs-pre.target, network.target and network-online.target, and
88 gain a Before= dependency on remote-fs.target unless nofail mount
89 option is set. Towards the latter a Wants= unit is added as well.
90 Mount units referring to local and network file systems are
92 distinguished by their file system type specification. In some cases
93 this is not sufficient (for example network block device based mounts,
94 such as iSCSI), in which case _netdev may be added to the mount option
95 string of the unit, which forces systemd to consider the mount unit a
96 network mount.
97
99 Mount units may either be configured via unit files, or via /etc/fstab
100 (see fstab(5) for details). Mounts listed in /etc/fstab will be
101 converted into native units dynamically at boot and when the
102 configuration of the system manager is reloaded. In general,
103 configuring mount points through /etc/fstab is the preferred approach
104 to manage mounts for humans. For tooling, writing mount units should be
105 preferred over editing /etc/fstab. See systemd-fstab-generator(8) for
106 details about the conversion from /etc/fstab to mount units.
107 The NFS mount option bg for NFS background mounts as documented in
109 nfs(5) is detected by systemd-fstab-generator and the options are
110 transformed so that systemd fulfills the job-control implications of
111 that option. Specifically systemd-fstab-generator acts as though
112 "x-systemd.mount-timeout=infinity,retry=10000" was prepended to the
113 option list, and "fg,nofail" was appended. Depending on specific
114 requirements, it may be appropriate to provide some of these options
115 explicitly, or to make use of the "x-systemd.automount" option
116 described below instead of using "bg".
117 When reading /etc/fstab a few special mount options are understood by
119 systemd which influence how dependencies are created for mount points.
120 systemd will create a dependency of type Wants= or Requires= (see
121 option nofail below), from either local-fs.target or remote-fs.target,
122 depending whether the file system is local or remote.
123 x-systemd.requires=
125 Configures a Requires= and an After= dependency between the created
126 mount unit and another systemd unit, such as a device or mount
127 unit. The argument should be a unit name, or an absolute path to a
128 device node or mount point. This option may be specified more than
129 once. This option is particularly useful for mount point
130 declarations that need an additional device to be around (such as
131 an external journal device for journal file systems) or an
132 additional mount to be in place (such as an overlay file system
133 that merges multiple mount points). See After= and Requires= in
134 systemd.unit(5) for details.
135 Note that this option always applies to the created mount unit only
137 regardless whether x-systemd.automount has been specified.
138 x-systemd.before=, x-systemd.after=
140 In the created mount unit, configures a Before= or After=
141 dependency on another systemd unit, such as a mount unit. The
142 argument should be a unit name or an absolute path to a mount
143 point. This option may be specified more than once. This option is
144 particularly useful for mount point declarations with nofail option
145 that are mounted asynchronously but need to be mounted before or
146 after some unit start, for example, before local-fs.target unit.
147 See Before= and After= in systemd.unit(5) for details.
148 Note that these options always apply to the created mount unit only
150 regardless whether x-systemd.automount has been specified.
151 x-systemd.wanted-by=, x-systemd.required-by=
153 In the created mount unit, configures a WantedBy= or RequiredBy=
154 dependency on another unit. This option may be specified more than
155 once. If this is specified, the normal automatic dependencies on
156 the created mount unit, e.g., local-fs.target, are not
157 automatically created. See WantedBy= and RequiredBy= in
158 systemd.unit(5) for details.
159 x-systemd.requires-mounts-for=
161 Configures a RequiresMountsFor= dependency between the created
162 mount unit and other mount units. The argument must be an absolute
163 path. This option may be specified more than once. See
164 RequiresMountsFor= in systemd.unit(5) for details.
165 x-systemd.device-bound
167 The block device backed file system will be upgraded to BindsTo=
168 dependency. This option is only useful when mounting file systems
169 manually with mount(8) as the default dependency in this case is
170 Requires=. This option is already implied by entries in /etc/fstab
171 or by mount units.
172 x-systemd.automount
174 An automount unit will be created for the file system. See
175 systemd.automount(5) for details.
176 x-systemd.idle-timeout=
178 Configures the idle timeout of the automount unit. See
179 TimeoutIdleSec= in systemd.automount(5) for details.
180 x-systemd.device-timeout=
182 Configure how long systemd should wait for a device to show up
183 before giving up on an entry from /etc/fstab. Specify a time in
184 seconds or explicitly append a unit such as "s", "min", "h", "ms".
185 Note that this option can only be used in /etc/fstab, and will be
187 ignored when part of the Options= setting in a unit file.
188 x-systemd.mount-timeout=
190 Configure how long systemd should wait for the mount command to
191 finish before giving up on an entry from /etc/fstab. Specify a time
192 in seconds or explicitly append a unit such as "s", "min", "h",
193 "ms".
194 Note that this option can only be used in /etc/fstab, and will be
196 ignored when part of the Options= setting in a unit file.
197 See TimeoutSec= below for details.
199 x-systemd.makefs
201 The file system will be initialized on the device. If the device is
202 not "empty", i.e. it contains any signature, the operation will be
203 skipped. It is hence expected that this option remains set even
204 after the device has been initialized.
205 Note that this option can only be used in /etc/fstab, and will be
207 ignored when part of the Options= setting in a unit file.
208 See systemd-makefs@.service(8).
210 wipefs(8) may be used to remove any signatures from a block device
212 to force x-systemd.makefs to reinitialize the device.
213 x-systemd.growfs
215 The file system will be grown to occupy the full block device. If
216 the file system is already at maximum size, no action will be
217 performed. It is hence expected that this option remains set even
218 after the file system has been grown. Only certain file system
219 types are supported, see systemd-makefs@.service(8) for details.
220 Note that this option can only be used in /etc/fstab, and will be
222 ignored when part of the Options= setting in a unit file.
223 x-systemd.rw-only
225 If a mount operation fails to mount the file system read-write, it
226 normally tries mounting the file system read-only instead. This
227 option disables that behaviour, and causes the mount to fail
228 immediately instead. This option is translated into the
229 ReadWriteOnly= setting in a unit file.
230 _netdev
232 Normally the file system type is used to determine if a mount is a
233 "network mount", i.e. if it should only be started after the
234 network is available. Using this option overrides this detection
235 and specifies that the mount requires network.
236 Network mount units are ordered between remote-fs-pre.target and
238 remote-fs.target, instead of local-fs-pre.target and
239 local-fs.target. They also pull in network-online.target and are
240 ordered after it and network.target.
241 noauto, auto
243 With noauto, the mount unit will not be added as a dependency for
244 local-fs.target or remote-fs.target. This means that it will not be
245 mounted automatically during boot, unless it is pulled in by some
246 other unit. The auto option has the opposite meaning and is the
247 default.
248 Note that if x-systemd.automount (see above) is used, neither auto
250 nor noauto have any effect. The matching automount unit will be
251 added as a dependency to the appropriate target.
252 nofail
254 With nofail, this mount will be only wanted, not required, by
255 local-fs.target or remote-fs.target. Moreover the mount unit is not
256 ordered before these target units. This means that the boot will
257 continue without waiting for the mount unit and regardless whether
258 the mount point can be mounted successfully.
259 x-initrd.mount
261 An additional filesystem to be mounted in the initramfs. See
262 initrd-fs.target description in systemd.special(7).
263 If a mount point is configured in both /etc/fstab and a unit file that
265 is stored below /usr/, the former will take precedence. If the unit
266 file is stored below /etc/, it will take precedence. This means: native
267 unit files take precedence over traditional configuration files, but
268 this is superseded by the rule that configuration in /etc/ will always
269 take precedence over configuration in /usr/.
270
272 Mount unit files may include [Unit] and [Install] sections, which are
273 described in systemd.unit(5).
274 Mount unit files must include a [Mount] section, which carries
276 information about the file system mount points it supervises. A number
277 of options that may be used in this section are shared with other unit
278 types. These options are documented in systemd.exec(5) and
279 systemd.kill(5). The options specific to the [Mount] section of mount
280 units are the following:
281 What=
283 Takes an absolute path of a device node, file or other resource to
284 mount. See mount(8) for details. If this refers to a device node, a
285 dependency on the respective device unit is automatically created.
286 (See systemd.device(5) for more information.) This option is
287 mandatory. Note that the usual specifier expansion is applied to
288 this setting, literal percent characters should hence be written as
289 "%%". If this mount is a bind mount and the specified path does not
290 exist yet it is created as directory.
291 Where=
293 Takes an absolute path of a file or directory for the mount point;
294 in particular, the destination cannot be a symbolic link. If the
295 mount point does not exist at the time of mounting, it is created
296 as directory. This string must be reflected in the unit filename.
297 (See above.) This option is mandatory.
298 Type=
300 Takes a string for the file system type. See mount(8) for details.
301 This setting is optional.
302 Options=
304 Mount options to use when mounting. This takes a comma-separated
305 list of options. This setting is optional. Note that the usual
306 specifier expansion is applied to this setting, literal percent
307 characters should hence be written as "%%".
308 SloppyOptions=
310 Takes a boolean argument. If true, parsing of the options specified
311 in Options= is relaxed, and unknown mount options are tolerated.
312 This corresponds with mount(8)'s -s switch. Defaults to off.
313 LazyUnmount=
315 Takes a boolean argument. If true, detach the filesystem from the
316 filesystem hierarchy at time of the unmount operation, and clean up
317 all references to the filesystem as soon as they are not busy
318 anymore. This corresponds with umount(8)'s -l switch. Defaults to
319 off.
320 ReadWriteOnly=
322 Takes a boolean argument. If false, a mount point that shall be
323 mounted read-write but cannot be mounted so is retried to be
324 mounted read-only. If true the operation will fail immediately
325 after the read-write mount attempt did not succeed. This
326 corresponds with mount(8)'s -w switch. Defaults to off.
327 ForceUnmount=
329 Takes a boolean argument. If true, force an unmount (in case of an
330 unreachable NFS system). This corresponds with umount(8)'s -f
331 switch. Defaults to off.
332 DirectoryMode=
334 Directories of mount points (and any parent directories) are
335 automatically created if needed. This option specifies the file
336 system access mode used when creating these directories. Takes an
337 access mode in octal notation. Defaults to 0755.
338 TimeoutSec=
340 Configures the time to wait for the mount command to finish. If a
341 command does not exit within the configured time, the mount will be
342 considered failed and be shut down again. All commands still
343 running will be terminated forcibly via SIGTERM, and after another
344 delay of this time with SIGKILL. (See KillMode= in
345 systemd.kill(5).) Takes a unit-less value in seconds, or a time
346 span value such as "5min 20s". Pass 0 to disable the timeout logic.
347 The default value is set from DefaultTimeoutStartSec= option in
348 systemd-system.conf(5).
349 Check systemd.unit(5), systemd.exec(5), and systemd.kill(5) for more
351 settings.
352
354 systemd(1), systemctl(1), systemd-system.conf(5), systemd.unit(5),
355 systemd.exec(5), systemd.kill(5), systemd.resource-control(5),
356 systemd.service(5), systemd.device(5), proc(5), mount(8), systemd-
357 fstab-generator(8), systemd.directives(7), systemd-mount(1)
358
360 1. API File Systems
361 https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
362systemd 251 SYSTEMD.MOUNT(5)