systemd.path - Path unit configuration
A unit configuration file whose name ends in ".path" encodes
information about a path monitored by systemd, for path-based activation.
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 path specific configuration
options are configured in the [Path] section.
For each path file, a matching unit file must exist, describing
the unit to activate when the path changes. By default, a service by the
same name as the path (except for the suffix) is activated. Example: a path
file foo.path activates a matching service foo.service. The unit to activate
may be controlled by Unit= (see below).
Internally, path units use the inotify(7) API to monitor
file systems. Due to that, it suffers by the same limitations as inotify,
and for example cannot be used to monitor files or directories changed by
other machines on remote NFS file systems.
When a service unit triggered by a path unit terminates
(regardless whether it exited successfully or failed), monitored paths are
checked immediately again, and the service accordingly restarted instantly.
As protection against busy looping in this trigger/start cycle, a start rate
limit is enforced on the service unit, see StartLimitIntervalSec= and
StartLimitBurst= in systemd.unit(5). Unlike other service
failures, the error condition that the start rate limit is hit is propagated
from the service unit to the path unit and causes the path unit to fail as
well, thus ending the loop.
The following dependencies are implicitly added:
•If a path unit is beneath another mount unit in
the file system hierarchy, both a requirement and an ordering dependency
between both units are created automatically.
•An implicit Before= dependency is added
between a path unit and the unit it is supposed to activate.
The following dependencies are added unless DefaultDependencies=no is
•Path units will automatically have dependencies
of type Before= on paths.target, dependencies of type After= and
Requires= on sysinit.target, and have dependencies of type
Conflicts= and Before= on shutdown.target. These ensure that
path units are terminated cleanly prior to system shutdown. Only path units
involved with early boot or late system shutdown should disable
Path files must include a [Path] section, which carries information about the
path(s) it monitors. The options specific to the [Path] section of path units
are the following:
PathExists=, PathExistsGlob=, PathChanged=,
Defines paths to monitor for certain changes:
may be used to watch the mere existence of a file or
directory. If the file specified exists, the configured unit is activated.
works similar, but checks for the existence of at least
one file matching the globbing pattern specified. PathChanged=
used to watch a file or directory and activate the configured unit whenever it
changes. It is not activated on every write to the watched file but it is
activated if the file which was open for writing gets closed.
is similar, but additionally it is activated also on
simple writes to the watched file. DirectoryNotEmpty=
may be used to
watch a directory and activate the configured unit whenever it contains at
least one file.
The arguments of these directives must be absolute file system
Multiple directives may be combined, of the same and of different
types, to watch multiple paths. If the empty string is assigned to any of
these options, the list of paths to watch is reset, and any prior
assignments of these options will not have any effect.
If a path already exists (in case of PathExists= and
PathExistsGlob=) or a directory already is not empty (in case of
DirectoryNotEmpty=) at the time the path unit is activated, then the
configured unit is immediately activated as well. Something similar does not
apply to PathChanged= and PathModified=.
If the path itself or any of the containing directories are not
accessible, systemd will watch for permission changes and notice that
conditions are satisfied when permissions allow that.
The unit to activate when any of the configured paths
changes. The argument is a unit name, whose suffix is not ".path".
If not specified, this value defaults to a service that has the same name as
the path unit, except for the suffix. (See above.) It is recommended that the
unit name that is activated and the unit name of the path unit are named
identical, except for the suffix.
Takes a boolean argument. If true, the directories to
watch are created before watching. This option is ignored for
PathExists= settings. Defaults to false.
If MakeDirectory= is enabled, use the mode
specified here to create the directories in question. Takes an access mode in
octal notation. Defaults to 0755.