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.
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16 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.
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22 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.
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28 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.
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33 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.
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40 Optionally, a mount unit may be accompanied by an automount unit, to
41 allow on-demand or parallelized mounting. See systemd.automount(5).
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43 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).
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47 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].
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53 Implicit Dependencies
54 The following dependencies are implicitly added:
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56 · If a mount unit is beneath another mount unit in the file system
57 hierarchy, both a requirement dependency and an ordering dependency
58 between both units are created automatically.
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60 · Block device backed file systems automatically gain BindsTo= and
61 After= type dependencies on the device unit encapsulating the block
62 device (see below).
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64 · If traditional file system quota is enabled for a mount unit,
65 automatic Wants= and Before= dependencies on
66 systemd-quotacheck.service and quotaon.service are added.
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68 · Additional implicit dependencies may be added as result of
69 execution and resource control parameters as documented in
70 systemd.exec(5) and systemd.resource-control(5).
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72 Default Dependencies
73 The following dependencies are added unless DefaultDependencies=no is
74 set:
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76 · All mount units acquire automatic Before= and Conflicts= on
77 umount.target in order to be stopped during shutdown.
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79 · Mount units referring to local file systems automatically gain an
80 After= dependency on local-fs-pre.target.
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82 · Network mount units automatically acquire After= dependencies on
83 remote-fs-pre.target, network.target and network-online.target.
84 Towards the latter a Wants= unit is added as well.
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86 Mount units referring to local and network file systems are
87 distinguished by their file system type specification. In some cases
88 this is not sufficient (for example network block device based mounts,
89 such as iSCSI), in which case _netdev may be added to the mount option
90 string of the unit, which forces systemd to consider the mount unit a
91 network mount.
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94 Mount units may either be configured via unit files, or via /etc/fstab
95 (see fstab(5) for details). Mounts listed in /etc/fstab will be
96 converted into native units dynamically at boot and when the
97 configuration of the system manager is reloaded. In general,
98 configuring mount points through /etc/fstab is the preferred approach.
99 See systemd-fstab-generator(8) for details about the conversion.
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101 The NFS mount option bg for NFS background mounts as documented in
102 nfs(5) is detected by systemd-fstab-generator and the options are
103 transformed so that systemd fulfills the job-control implications of
104 that option. Specifically systemd-fstab-generator acts as though
105 "x-systemd.mount-timout=infinity,retry=10000" was prepended to the
106 option list, and "fg,nofail" was appended. Depending on specific
107 requirements, it may be appropriate to provide some of these options
108 explicitly, or to make use of the "x-systemd.automount" option
109 described below instead of using "bg".
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111 When reading /etc/fstab a few special mount options are understood by
112 systemd which influence how dependencies are created for mount points.
113 systemd will create a dependency of type Wants= or Requires (see option
114 nofail below), from either local-fs.target or remote-fs.target,
115 depending whether the file system is local or remote.
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117 x-systemd.requires=
118 Configures a Requires= and an After= dependency between the created
119 mount unit and another systemd unit, such as a device or mount
120 unit. The argument should be a unit name, or an absolute path to a
121 device node or mount point. This option may be specified more than
122 once. This option is particularly useful for mount point
123 declarations that need an additional device to be around (such as
124 an external journal device for journal file systems) or an
125 additional mount to be in place (such as an overlay file system
126 that merges multiple mount points). See After= and Requires= in
127 systemd.unit(5) for details.
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129 x-systemd.before=, x-systemd.after=
130 Configures a Before= dependency or After= between the created mount
131 unit and another systemd unit, such as a mount unit. The argument
132 should be a unit name or an absolute path to a mount point. This
133 option may be specified more than once. This option is particularly
134 useful for mount point declarations with nofail option that are
135 mounted asynchronously but need to be mounted before or after some
136 unit start, for example, before local-fs.target unit. See Before=
137 and After= in systemd.unit(5) for details.
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139 x-systemd.requires-mounts-for=
140 Configures a RequiresMountsFor= dependency between the created
141 mount unit and other mount units. The argument must be an absolute
142 path. This option may be specified more than once. See
143 RequiresMountsFor= in systemd.unit(5) for details.
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145 x-systemd.device-bound
146 The block device backed file system will be upgraded to BindsTo=
147 dependency. This option is only useful when mounting file systems
148 manually with mount(8) as the default dependency in this case is
149 Requires=. This option is already implied by entries in /etc/fstab
150 or by mount units.
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152 x-systemd.automount
153 An automount unit will be created for the file system. See
154 systemd.automount(5) for details.
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156 x-systemd.idle-timeout=
157 Configures the idle timeout of the automount unit. See
158 TimeoutIdleSec= in systemd.automount(5) for details.
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160 x-systemd.device-timeout=
161 Configure how long systemd should wait for a device to show up
162 before giving up on an entry from /etc/fstab. Specify a time in
163 seconds or explicitly append a unit such as "s", "min", "h", "ms".
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165 Note that this option can only be used in /etc/fstab, and will be
166 ignored when part of the Options= setting in a unit file.
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168 x-systemd.mount-timeout=
169 Configure how long systemd should wait for the mount command to
170 finish before giving up on an entry from /etc/fstab. Specify a time
171 in seconds or explicitly append a unit such as "s", "min", "h",
172 "ms".
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174 Note that this option can only be used in /etc/fstab, and will be
175 ignored when part of the Options= setting in a unit file.
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177 See TimeoutSec= below for details.
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179 x-systemd.makefs
180 The file system or swap structure will be initialized on the
181 device. If the device is not "empty", i.e. it contains any
182 signature, the operation will be skipped. It is hence expected that
183 this option remains set even after the device has been initalized.
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185 Note that this option can only be used in /etc/fstab, and will be
186 ignored when part of the Options= setting in a unit file.
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188 See systemd-makefs@.service(8).
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190 wipefs(8) may be used to remove any signatures from a block device
191 to force x-systemd.makefs to reinitialize the device.
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193 x-systemd.growfs
194 The file system will be grown to occupy the full block device. If
195 the file system is already at maximum size, no action will be
196 performed. It is hence expected that this option remains set even
197 after the file system has been grown. Only certain file system
198 types are supported, see systemd-makefs@.service(8) for details.
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200 Note that this option can only be used in /etc/fstab, and will be
201 ignored when part of the Options= setting in a unit file.
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203 _netdev
204 Normally the file system type is used to determine if a mount is a
205 "network mount", i.e. if it should only be started after the
206 network is available. Using this option overrides this detection
207 and specifies that the mount requires network.
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209 Network mount units are ordered between remote-fs-pre.target and
210 remote-fs.target, instead of local-fs-pre.target and
211 local-fs.target. They also pull in network-online.target and are
212 ordered after it and network.target.
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214 noauto, auto
215 With noauto, the mount unit will not be added as a dependency for
216 local-fs.target or remote-fs.target. This means that it will not be
217 mounted automatically during boot, unless it is pulled in by some
218 other unit. The auto option has the opposite meaning and is the
219 default. Note that the noauto option has an effect on the mount
220 unit itself only — if x-systemd.automount is used (see above), then
221 the matching automount unit will still be pulled in by these
222 targets.
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224 nofail
225 With nofail, this mount will be only wanted, not required, by
226 local-fs.target or remote-fs.target. Moreover the mount unit is not
227 ordered before these target units. This means that the boot will
228 continue without waiting for the mount unit and regardless whether
229 the mount point can be mounted successfully.
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231 x-initrd.mount
232 An additional filesystem to be mounted in the initramfs. See
233 initrd-fs.target description in systemd.special(7).
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235 If a mount point is configured in both /etc/fstab and a unit file that
236 is stored below /usr, the former will take precedence. If the unit file
237 is stored below /etc, it will take precedence. This means: native unit
238 files take precedence over traditional configuration files, but this is
239 superseded by the rule that configuration in /etc will always take
240 precedence over configuration in /usr.
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243 Mount files must include a [Mount] section, which carries information
244 about the file system mount points it supervises. A number of options
245 that may be used in this section are shared with other unit types.
246 These options are documented in systemd.exec(5) and systemd.kill(5).
247 The options specific to the [Mount] section of mount units are the
248 following:
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250 What=
251 Takes an absolute path of a device node, file or other resource to
252 mount. See mount(8) for details. If this refers to a device node, a
253 dependency on the respective device unit is automatically created.
254 (See systemd.device(5) for more information.) This option is
255 mandatory. Note that the usual specifier expansion is applied to
256 this setting, literal percent characters should hence be written as
257 "%%".
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259 Where=
260 Takes an absolute path of a directory for the mount point; in
261 particular, the destination cannot be a symbolic link. If the mount
262 point does not exist at the time of mounting, it is created. This
263 string must be reflected in the unit filename. (See above.) This
264 option is mandatory.
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266 Type=
267 Takes a string for the file system type. See mount(8) for details.
268 This setting is optional.
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270 Options=
271 Mount options to use when mounting. This takes a comma-separated
272 list of options. This setting is optional. Note that the usual
273 specifier expansion is applied to this setting, literal percent
274 characters should hence be written as "%%".
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276 SloppyOptions=
277 Takes a boolean argument. If true, parsing of the options specified
278 in Options= is relaxed, and unknown mount options are tolerated.
279 This corresponds with mount(8)'s -s switch. Defaults to off.
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281 LazyUnmount=
282 Takes a boolean argument. If true, detach the filesystem from the
283 filesystem hierarchy at time of the unmount operation, and clean up
284 all references to the filesystem as soon as they are not busy
285 anymore. This corresponds with umount(8)'s -l switch. Defaults to
286 off.
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288 ForceUnmount=
289 Takes a boolean argument. If true, force an unmount (in case of an
290 unreachable NFS system). This corresponds with umount(8)'s -f
291 switch. Defaults to off.
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293 DirectoryMode=
294 Directories of mount points (and any parent directories) are
295 automatically created if needed. This option specifies the file
296 system access mode used when creating these directories. Takes an
297 access mode in octal notation. Defaults to 0755.
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299 TimeoutSec=
300 Configures the time to wait for the mount command to finish. If a
301 command does not exit within the configured time, the mount will be
302 considered failed and be shut down again. All commands still
303 running will be terminated forcibly via SIGTERM, and after another
304 delay of this time with SIGKILL. (See KillMode= in
305 systemd.kill(5).) Takes a unit-less value in seconds, or a time
306 span value such as "5min 20s". Pass 0 to disable the timeout logic.
307 The default value is set from the manager configuration file's
308 DefaultTimeoutStartSec= variable.
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310 Check systemd.exec(5) and systemd.kill(5) for more settings.
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313 systemd(1), systemctl(1), systemd.unit(5), systemd.exec(5),
314 systemd.kill(5), systemd.resource-control(5), systemd.service(5),
315 systemd.device(5), proc(5), mount(8), systemd-fstab-generator(8),
316 systemd.directives(7)
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319 1. API File Systems
320 https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
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324systemd 239 SYSTEMD.MOUNT(5)