1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
'\" t
.TH "SYSTEMD\&.PATH" "5" "" "systemd 256~rc3" "systemd.path"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
systemd.path \- Path unit configuration
.SH "SYNOPSIS"
.PP
\fIpath\fR\&.path
.SH "DESCRIPTION"
.PP
A unit configuration file whose name ends in
"\&.path"
encodes information about a path monitored by systemd, for path\-based activation\&.
.PP
This man page lists the configuration options specific to this unit type\&. See
\fBsystemd.unit\fR(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\&.
.PP
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
\fIUnit=\fR
(see below)\&.
.PP
Internally, path units use the
\fBinotify\fR(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\&.
.PP
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
\fIStartLimitIntervalSec=\fR
and
\fIStartLimitBurst=\fR
in
\fBsystemd.unit\fR(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\&.
.SH "AUTOMATIC DEPENDENCIES"
.SS "Implicit Dependencies"
.PP
The following dependencies are implicitly added:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
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\&.
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
An implicit
\fIBefore=\fR
dependency is added between a path unit and the unit it is supposed to activate\&.
.RE
.SS "Default Dependencies"
.PP
The following dependencies are added unless
\fIDefaultDependencies=no\fR
is set:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
Path units will automatically have dependencies of type
\fIBefore=\fR
on
paths\&.target, dependencies of type
\fIAfter=\fR
and
\fIRequires=\fR
on
sysinit\&.target, and have dependencies of type
\fIConflicts=\fR
and
\fIBefore=\fR
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
\fIDefaultDependencies=\fR
option\&.
.RE
.PP
.SH "OPTIONS"
.PP
Path unit files may include [Unit] and [Install] sections, which are described in
\fBsystemd.unit\fR(5)\&.
.PP
Path unit files must include a [Path] section, which carries information about the path or paths it monitors\&. The options specific to the [Path] section of path units are the following:
.PP
\fIPathExists=\fR, \fIPathExistsGlob=\fR, \fIPathChanged=\fR, \fIPathModified=\fR, \fIDirectoryNotEmpty=\fR
.RS 4
Defines paths to monitor for certain changes:
\fIPathExists=\fR
may be used to watch the mere existence of a file or directory\&. If the file specified exists, the configured unit is activated\&.
\fIPathExistsGlob=\fR
works similarly, but checks for the existence of at least one file matching the globbing pattern specified\&.
\fIPathChanged=\fR
may be 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\&.
\fIPathModified=\fR
is similar, but additionally it is activated also on simple writes to the watched file\&.
\fIDirectoryNotEmpty=\fR
may be used to watch a directory and activate the configured unit whenever it contains at least one file\&.
.sp
The arguments of these directives must be absolute file system paths\&.
.sp
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\&.
.sp
If a path already exists (in case of
\fIPathExists=\fR
and
\fIPathExistsGlob=\fR) or a directory already is not empty (in case of
\fIDirectoryNotEmpty=\fR) at the time the path unit is activated, then the configured unit is immediately activated as well\&. Something similar does not apply to
\fIPathChanged=\fR
and
\fIPathModified=\fR\&.
.sp
If the path itself or any of the containing directories are not accessible,
\fBsystemd\fR
will watch for permission changes and notice that conditions are satisfied when permissions allow that\&.
.RE
.PP
\fIUnit=\fR
.RS 4
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\&.
.RE
.PP
\fIMakeDirectory=\fR
.RS 4
Takes a boolean argument\&. If true, the directories to watch are created before watching\&. This option is ignored for
\fIPathExists=\fR
settings\&. Defaults to
\fBfalse\fR\&.
.RE
.PP
\fIDirectoryMode=\fR
.RS 4
If
\fIMakeDirectory=\fR
is enabled, use the mode specified here to create the directories in question\&. Takes an access mode in octal notation\&. Defaults to
\fB0755\fR\&.
.RE
.PP
\fITriggerLimitIntervalSec=\fR, \fITriggerLimitBurst=\fR
.RS 4
Configures a limit on how often this path unit may be activated within a specific time interval\&. The
\fITriggerLimitIntervalSec=\fR
may be used to configure the length of the time interval in the usual time units
"us",
"ms",
"s",
"min",
"h", \&... and defaults to 2s\&. See
\fBsystemd.time\fR(7)
for details on the various time units understood\&. The
\fITriggerLimitBurst=\fR
setting takes a positive integer value and specifies the number of permitted activations per time interval, and defaults to 200\&. Set either to 0 to disable any form of trigger rate limiting\&. If the limit is hit, the unit is placed into a failure mode, and will not watch the paths anymore until restarted\&. Note that this limit is enforced before the service activation is enqueued\&.
.sp
Added in version 250\&.
.RE
.PP
Check
\fBsystemd.unit\fR(5),
\fBsystemd.exec\fR(5), and
\fBsystemd.kill\fR(5)
for more settings\&.
.SH "SEE ALSO"
.PP
Environment variables with details on the trigger will be set for triggered units\&. See the section
"Environment Variables Set or Propagated by the Service Manager"
in
\fBsystemd.exec\fR(5)
for more details\&.
.PP
\fBsystemd\fR(1), \fBsystemctl\fR(1), \fBsystemd.unit\fR(5), \fBsystemd.service\fR(5), \fBinotify\fR(7), \fBsystemd.directives\fR(7)
|
