| 1. | API File Systems |
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:
Default Dependencies
The following dependencies are added unless DefaultDependencies=no is set:
Additionally, an After= dependency on swap.target is added when the file system type is "tmpfs".
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=
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=
Added in version 257.
x-systemd.before=, x-systemd.after=
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=
Added in version 245.
x-systemd.wants-mounts-for=, x-systemd.requires-mounts-for=
Added in version 220.
x-systemd.device-bound=
Added in version 233.
x-systemd.automount
Added in version 215.
x-systemd.idle-timeout=
Added in version 220.
x-systemd.device-timeout=
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=
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
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 [email protected](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
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
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
Added in version 246.
_netdev
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
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
Added in version 215.
x-initrd.mount
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=
Where=
Type=
If the type is "overlay", and "upperdir=" or "workdir=" are specified as options and the directories do not exist, they will be created.
Options=
SloppyOptions=
Added in version 215.
LazyUnmount=
Added in version 232.
ReadWriteOnly=
Added in version 246.
ForceUnmount=
Added in version 232.
DirectoryMode=
TimeoutSec=
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