CLI: make list-triggers command print capture expressions
[lttng-tools.git] / doc / man / lttng-add-trigger.1.txt
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1lttng-add-trigger(1)
2=====================
3:revdate: 17 January 2020
4
5
6NAME
7----
8lttng-add-trigger - Create LTTng triggers
9
10
11SYNOPSIS
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
22DESCRIPTION
23-----------
24
25The `lttng add-trigger` command is used to create triggers. A
26trigger is an association between a *condition* and one or more
27*actions*. When the condition associated to a trigger is met, the
28actions associated to that trigger are executed. The tracing does not
29have to be active for the conditions to be met, and triggers are
30independent from tracing sessions.
31
32By default, a trigger fires every time its condition is met. The
33'--fire-every' and '--fire-once-after' options can be used to change
34this mode.
35
36The syntax by which conditions and actions are specified is described
37below.
38
d0a70fd5 39[[conditions]]
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40Conditions
41~~~~~~~~~~
42
43Conditions are specified with the `--condition` option, followed by a
44condition name, and possibly some more arguments, depending on the
45specific condition. There must be exactly one condition given in the
46`lttng add-trigger` invocation.
47
48The available conditions are:
49
50Event rule: `on-event [event rule arguments]`::
51 This type of condition is met when the tracer encounters an event
52 matching the given even rule. The arguments describing the event
53 rule are the same as those describing the event rules of the
54 man:lttng-enable-event(1) command, with these exceptions:
55
56 - It is not possible to use filter operands that use values from
57 the context.
58
d0a70fd5 59[[actions]]
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60Actions
61~~~~~~~
62
63Actions are specified with the `--action` option, followed by an action
64name, and possibly some more arguments, depending on the specific
65action. There must be at least one action given in the
66`lttng add-trigger` invocation.
67
68The available actions are:
69
70Notify: *notify*::
71 This action causes the LTTng session daemon to send a notification,
72 through its notification mechanism (see man:lttng-sessiond(8)).
73 Some details about the condition evaluation are sent along with the
74 notification.
75
76Start session: *start-session* session-name::
77 This action causes the LTTng session daemon to start tracing for the
78 session with the given name. If no session with the given name exist
79 at the time the condition is met, nothing is done.
80
81Stop session: *stop-session* session-name::
82 This action causes the LTTng session daemon to stop tracing for the
83 session with the given name. If no session with the given name exist
84 at the time the condition is met, nothing is done.
85
86Rotate session: *rotate-session* session-name::
87 This action causes the LTTng session daemon to rotate the session
88 with the given name. See man:lttng-rotate(1) for more information
89 about the session rotation concept. If no session with the given
90 name exist at the time the condition is met, nothing is done.
91
92Snapshot session: *snapshot-session* session-name::
93 This action causes the LTTng session daemon to take a snapshot of the
94 session with the given name. See man:lttng-snapshot(1) for more
95 information about the session snapshot concept. If no session with
96 the given name exist at the time the condition is met, nothing is
97 done.
98
99OPTIONS
100-------
101
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102option:--condition::
103 Define the condition for the trigger. See the
104 <<conditions,CONDITIONS>> section for more details.
105
106option:--action::
107 Define an action for the trigger. See the <<actions,ACTIONS>>
108 section for more details.
109
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110option:--id='ID'::
111 Set the id of the trigger to 'ID'. If omitted, an id will
112 automatically be assigned to the trigger by the session daemon.
113+
114If a trigger with the specified 'ID' already exists, the trigger
115creation will fail.
116
117option:--fire-every 'N'::
118 Execute the trigger's actions every 'N' times the condition is met.
119
120option:--fire-once-after 'N'::
121 Execute the trigger's actions once after 'N' times the condition is
122 met, then never after that.
123
124include::common-cmd-help-options.txt[]
125
126
127include::common-cmd-footer.txt[]
128
129
130SEE ALSO
131--------
132man:lttng-list-triggers(1),
133man:lttng-remove-trigger(1),
134man:lttng(1)
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