Docs: Add lttng-add-trigger man page
[lttng-tools.git] / doc / man / lttng-add-trigger.1.txt
1 lttng-add-trigger(1)
2 =====================
3 :revdate: 17 January 2020
4
5
6 NAME
7 ----
8 lttng-add-trigger - Create LTTng triggers
9
10
11 SYNOPSIS
12 --------
13
14 [verse]
15 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *add-trigger* [--id ID]
16 [--fire-every N] [--fire-once-after N]
17 --condition CONDITION-NAME CONDITION-ARGS
18 --action ACTION-NAME ACTION-ARGS
19 [--action ACTION-NAME ACTION-ARGS]...
20
21
22 DESCRIPTION
23 -----------
24
25 The `lttng add-trigger` command is used to create triggers. A
26 trigger is an association between a *condition* and one or more
27 *actions*. When the condition associated to a trigger is met, the
28 actions associated to that trigger are executed. The tracing does not
29 have to be active for the conditions to be met, and triggers are
30 independent from tracing sessions.
31
32 By default, a trigger fires every time its condition is met. The
33 '--fire-every' and '--fire-once-after' options can be used to change
34 this mode.
35
36 The syntax by which conditions and actions are specified is described
37 below.
38
39 Conditions
40 ~~~~~~~~~~
41
42 Conditions are specified with the `--condition` option, followed by a
43 condition name, and possibly some more arguments, depending on the
44 specific condition. There must be exactly one condition given in the
45 `lttng add-trigger` invocation.
46
47 The available conditions are:
48
49 Event rule: `on-event [event rule arguments]`::
50 This type of condition is met when the tracer encounters an event
51 matching the given even rule. The arguments describing the event
52 rule are the same as those describing the event rules of the
53 man:lttng-enable-event(1) command, with these exceptions:
54
55 - It is not possible to use filter operands that use values from
56 the context.
57
58 Actions
59 ~~~~~~~
60
61 Actions are specified with the `--action` option, followed by an action
62 name, and possibly some more arguments, depending on the specific
63 action. There must be at least one action given in the
64 `lttng add-trigger` invocation.
65
66 The available actions are:
67
68 Notify: *notify*::
69 This action causes the LTTng session daemon to send a notification,
70 through its notification mechanism (see man:lttng-sessiond(8)).
71 Some details about the condition evaluation are sent along with the
72 notification.
73
74 Start session: *start-session* session-name::
75 This action causes the LTTng session daemon to start tracing for the
76 session with the given name. If no session with the given name exist
77 at the time the condition is met, nothing is done.
78
79 Stop session: *stop-session* session-name::
80 This action causes the LTTng session daemon to stop tracing for the
81 session with the given name. If no session with the given name exist
82 at the time the condition is met, nothing is done.
83
84 Rotate session: *rotate-session* session-name::
85 This action causes the LTTng session daemon to rotate the session
86 with the given name. See man:lttng-rotate(1) for more information
87 about the session rotation concept. If no session with the given
88 name exist at the time the condition is met, nothing is done.
89
90 Snapshot session: *snapshot-session* session-name::
91 This action causes the LTTng session daemon to take a snapshot of the
92 session with the given name. See man:lttng-snapshot(1) for more
93 information about the session snapshot concept. If no session with
94 the given name exist at the time the condition is met, nothing is
95 done.
96
97 OPTIONS
98 -------
99
100 option:--id='ID'::
101 Set the id of the trigger to 'ID'. If omitted, an id will
102 automatically be assigned to the trigger by the session daemon.
103 +
104 If a trigger with the specified 'ID' already exists, the trigger
105 creation will fail.
106
107 option:--fire-every 'N'::
108 Execute the trigger's actions every 'N' times the condition is met.
109
110 option:--fire-once-after 'N'::
111 Execute the trigger's actions once after 'N' times the condition is
112 met, then never after that.
113
114 include::common-cmd-help-options.txt[]
115
116
117 include::common-cmd-footer.txt[]
118
119
120 SEE ALSO
121 --------
122 man:lttng-list-triggers(1),
123 man:lttng-remove-trigger(1),
124 man:lttng(1)
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