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 See systemd-fstab-generator(8) for details about the conversion.
105 The NFS mount option bg for NFS background mounts as documented in
107 nfs(5) is detected by systemd-fstab-generator and the options are
108 transformed so that systemd fulfills the job-control implications of
109 that option. Specifically systemd-fstab-generator acts as though
110 "x-systemd.mount-timeout=infinity,retry=10000" was prepended to the
111 option list, and "fg,nofail" was appended. Depending on specific
112 requirements, it may be appropriate to provide some of these options
113 explicitly, or to make use of the "x-systemd.automount" option
114 described below instead of using "bg".
115 When reading /etc/fstab a few special mount options are understood by
117 systemd which influence how dependencies are created for mount points.
118 systemd will create a dependency of type Wants= or Requires= (see
119 option nofail below), from either local-fs.target or remote-fs.target,
120 depending whether the file system is local or remote.
121 x-systemd.requires=
123 Configures a Requires= and an After= dependency between the created
124 mount unit and another systemd unit, such as a device or mount
125 unit. The argument should be a unit name, or an absolute path to a
126 device node or mount point. This option may be specified more than
127 once. This option is particularly useful for mount point
128 declarations that need an additional device to be around (such as
129 an external journal device for journal file systems) or an
130 additional mount to be in place (such as an overlay file system
131 that merges multiple mount points). See After= and Requires= in
132 systemd.unit(5) for details.
133 Note that this option always applies to the created mount unit only
135 regardless whether x-systemd.automount has been specified.
136 x-systemd.before=, x-systemd.after=
138 In the created mount unit, configures a Before= or After=
139 dependency on another systemd unit, such as a mount unit. The
140 argument should be a unit name or an absolute path to a mount
141 point. This option may be specified more than once. This option is
142 particularly useful for mount point declarations with nofail option
143 that are mounted asynchronously but need to be mounted before or
144 after some unit start, for example, before local-fs.target unit.
145 See Before= and After= in systemd.unit(5) for details.
146 Note that these options always apply to the created mount unit only
148 regardless whether x-systemd.automount has been specified.
149 x-systemd.wanted-by=, x-systemd.required-by=
151 In the created mount unit, configures a WantedBy= or RequiredBy=
152 dependency on another unit. This option may be specified more than
153 once. If this is specified, the normal automatic dependencies on
154 the created mount unit, e.g., local-fs.target, are not
155 automatically created. See WantedBy= and RequiredBy= in
156 systemd.unit(5) for details.
157 x-systemd.requires-mounts-for=
159 Configures a RequiresMountsFor= dependency between the created
160 mount unit and other mount units. The argument must be an absolute
161 path. This option may be specified more than once. See
162 RequiresMountsFor= in systemd.unit(5) for details.
163 x-systemd.device-bound
165 The block device backed file system will be upgraded to BindsTo=
166 dependency. This option is only useful when mounting file systems
167 manually with mount(8) as the default dependency in this case is
168 Requires=. This option is already implied by entries in /etc/fstab
169 or by mount units.
170 x-systemd.automount
172 An automount unit will be created for the file system. See
173 systemd.automount(5) for details.
174 x-systemd.idle-timeout=
176 Configures the idle timeout of the automount unit. See
177 TimeoutIdleSec= in systemd.automount(5) for details.
178 x-systemd.device-timeout=
180 Configure how long systemd should wait for a device to show up
181 before giving up on an entry from /etc/fstab. Specify a time in
182 seconds or explicitly append a unit such as "s", "min", "h", "ms".
183 Note that this option can only be used in /etc/fstab, and will be
185 ignored when part of the Options= setting in a unit file.
186 x-systemd.mount-timeout=
188 Configure how long systemd should wait for the mount command to
189 finish before giving up on an entry from /etc/fstab. Specify a time
190 in seconds or explicitly append a unit such as "s", "min", "h",
191 "ms".
192 Note that this option can only be used in /etc/fstab, and will be
194 ignored when part of the Options= setting in a unit file.
195 See TimeoutSec= below for details.
197 x-systemd.makefs
199 The file system will be initialized on the device. If the device is
200 not "empty", i.e. it contains any signature, the operation will be
201 skipped. It is hence expected that this option remains set even
202 after the device has been initialized.
203 Note that this option can only be used in /etc/fstab, and will be
205 ignored when part of the Options= setting in a unit file.
206 See systemd-makefs@.service(8).
208 wipefs(8) may be used to remove any signatures from a block device
210 to force x-systemd.makefs to reinitialize the device.
211 x-systemd.growfs
213 The file system will be grown to occupy the full block device. If
214 the file system is already at maximum size, no action will be
215 performed. It is hence expected that this option remains set even
216 after the file system has been grown. Only certain file system
217 types are supported, see systemd-makefs@.service(8) for details.
218 Note that this option can only be used in /etc/fstab, and will be
220 ignored when part of the Options= setting in a unit file.
221 x-systemd.rw-only
223 If a mount operation fails to mount the file system read-write, it
224 normally tries mounting the file system read-only instead. This
225 option disables that behaviour, and causes the mount to fail
226 immediately instead. This option is translated into the
227 ReadWriteOnly= setting in a unit file.
228 _netdev
230 Normally the file system type is used to determine if a mount is a
231 "network mount", i.e. if it should only be started after the
232 network is available. Using this option overrides this detection
233 and specifies that the mount requires network.
234 Network mount units are ordered between remote-fs-pre.target and
236 remote-fs.target, instead of local-fs-pre.target and
237 local-fs.target. They also pull in network-online.target and are
238 ordered after it and network.target.
239 noauto, auto
241 With noauto, the mount unit will not be added as a dependency for
242 local-fs.target or remote-fs.target. This means that it will not be
243 mounted automatically during boot, unless it is pulled in by some
244 other unit. The auto option has the opposite meaning and is the
245 default. Note that the noauto option has an effect on the mount
246 unit itself only — if x-systemd.automount is used (see above), then
247 the matching automount unit will still be pulled in by these
248 targets.
249 nofail
251 With nofail, this mount will be only wanted, not required, by
252 local-fs.target or remote-fs.target. Moreover the mount unit is not
253 ordered before these target units. This means that the boot will
254 continue without waiting for the mount unit and regardless whether
255 the mount point can be mounted successfully.
256 x-initrd.mount
258 An additional filesystem to be mounted in the initramfs. See
259 initrd-fs.target description in systemd.special(7).
260 If a mount point is configured in both /etc/fstab and a unit file that
262 is stored below /usr, the former will take precedence. If the unit file
263 is stored below /etc, it will take precedence. This means: native unit
264 files take precedence over traditional configuration files, but this is
265 superseded by the rule that configuration in /etc will always take
266 precedence over configuration in /usr.
267
269 Mount files must include a [Mount] section, which carries information
270 about the file system mount points it supervises. A number of options
271 that may be used in this section are shared with other unit types.
272 These options are documented in systemd.exec(5) and systemd.kill(5).
273 The options specific to the [Mount] section of mount units are the
274 following:
275 What=
277 Takes an absolute path of a device node, file or other resource to
278 mount. See mount(8) for details. If this refers to a device node, a
279 dependency on the respective device unit is automatically created.
280 (See systemd.device(5) for more information.) This option is
281 mandatory. Note that the usual specifier expansion is applied to
282 this setting, literal percent characters should hence be written as
283 "%%". If this mount is a bind mount and the specified path does not
284 exist yet it is created as directory.
285 Where=
287 Takes an absolute path of a file or directory for the mount point;
288 in particular, the destination cannot be a symbolic link. If the
289 mount point does not exist at the time of mounting, it is created
290 as directory. This string must be reflected in the unit filename.
291 (See above.) This option is mandatory.
292 Type=
294 Takes a string for the file system type. See mount(8) for details.
295 This setting is optional.
296 Options=
298 Mount options to use when mounting. This takes a comma-separated
299 list of options. This setting is optional. Note that the usual
300 specifier expansion is applied to this setting, literal percent
301 characters should hence be written as "%%".
302 SloppyOptions=
304 Takes a boolean argument. If true, parsing of the options specified
305 in Options= is relaxed, and unknown mount options are tolerated.
306 This corresponds with mount(8)'s -s switch. Defaults to off.
307 LazyUnmount=
309 Takes a boolean argument. If true, detach the filesystem from the
310 filesystem hierarchy at time of the unmount operation, and clean up
311 all references to the filesystem as soon as they are not busy
312 anymore. This corresponds with umount(8)'s -l switch. Defaults to
313 off.
314 ReadWriteOnly=
316 Takes a boolean argument. If false, a mount point that shall be
317 mounted read-write but cannot be mounted so is retried to be
318 mounted read-only. If true the operation will fail immediately
319 after the read-write mount attempt did not succeed. This
320 corresponds with mount(8)'s -w switch. Defaults to off.
321 ForceUnmount=
323 Takes a boolean argument. If true, force an unmount (in case of an
324 unreachable NFS system). This corresponds with umount(8)'s -f
325 switch. Defaults to off.
326 DirectoryMode=
328 Directories of mount points (and any parent directories) are
329 automatically created if needed. This option specifies the file
330 system access mode used when creating these directories. Takes an
331 access mode in octal notation. Defaults to 0755.
332 TimeoutSec=
334 Configures the time to wait for the mount command to finish. If a
335 command does not exit within the configured time, the mount will be
336 considered failed and be shut down again. All commands still
337 running will be terminated forcibly via SIGTERM, and after another
338 delay of this time with SIGKILL. (See KillMode= in
339 systemd.kill(5).) Takes a unit-less value in seconds, or a time
340 span value such as "5min 20s". Pass 0 to disable the timeout logic.
341 The default value is set from DefaultTimeoutStartSec= option in
342 systemd-system.conf(5).
343 Check systemd.exec(5) and systemd.kill(5) for more settings.
345
347 systemd(1), systemctl(1), systemd-system.conf(5), systemd.unit(5),
348 systemd.exec(5), systemd.kill(5), systemd.resource-control(5),
349 systemd.service(5), systemd.device(5), proc(5), mount(8), systemd-
350 fstab-generator(8), systemd.directives(7), systemd-mount(1)
351
353 1. API File Systems
354 https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
355systemd 246 SYSTEMD.MOUNT(5)