Check for pending notification on notification channel activity
[lttng-tools.git] / doc / man / lttng-create.1.txt
1 lttng-create(1)
2 ===============
3
4
5 NAME
6 ----
7 lttng-create - Create an LTTng tracing session
8
9
10 SYNOPSIS
11 --------
12 Local mode:
13
14 [verse]
15 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] [option:--shm-path='PATH']
16 [option:--no-output | option:--output='PATH' | option:--set-url=file://'PATH']
17
18 Network streaming mode:
19
20 [verse]
21 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] [option:--shm-path='PATH']
22 (option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL')
23 Snapshot mode:
24
25 [verse]
26 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] option:--snapshot
27 [option:--shm-path='PATH'] [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL']
28
29 Live mode:
30
31 [verse]
32 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] option:--live[='DELAYUS']
33 [option:--shm-path='PATH'] [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL']
34
35 DESCRIPTION
36 -----------
37 The `lttng create` command creates a new tracing session.
38
39 A tracing session is a named container of channels, which in turn
40 contain event rules. It is domain-agnostic, in that channels and event
41 rules can be enabled for the user space tracer and/or the Linux
42 kernel tracer.
43
44 On execution, an `.lttngrc` file is created, if it does not exist, in the
45 user's home directory. This file contains the name of the current tracing
46 session. When creating a new tracing session with `lttng create`, the
47 current tracing session is set to this new tracing session. The
48 man:lttng-set-session(1) command can be used to set the current
49 tracing session without manually editing the `.lttngrc` file.
50
51 If 'SESSION' is omitted, a session name is automatically created having
52 this form: `auto-YYYYmmdd-HHMMSS`. 'SESSION' *must not* contain the
53 character `/`.
54
55 The option:--shm-path option can be used to specify the path to the
56 shared memory holding the ring buffers. Specifying a location on an
57 NVRAM file system makes it possible to retrieve the latest recorded
58 trace data when the system reboots after a crash. To view the events
59 of ring buffer files after a system crash, use the
60 man:lttng-crash(1) utility.
61
62 Tracing sessions are destroyed using the man:lttng-destroy(1)
63 command.
64
65
66 Creation modes
67 ~~~~~~~~~~~~~~
68 There are four tracing session modes:
69
70 [[local-mode]]Local mode::
71 Traces the local system and writes the trace to the local
72 file system. The option:--output option specifies the trace path.
73 Using option:--set-url=file://'PATH' is the equivalent of using
74 option:--output='PATH'. The file system output can be disabled using
75 the option:--no-output option.
76 +
77 If none of the options mentioned above are used, then the trace is
78 written locally in the `$LTTNG_HOME/lttng-traces` directory
79 (`$LTTNG_HOME` defaults to `$HOME`).
80
81 [[network-streaming-mode]]Network streaming mode::
82 Traces the local system and sends the trace over the network to
83 a listening relay daemon (see man:lttng-relayd(8)).
84 The option:--set-url, or option:--ctrl-url and option:--data-url
85 options set the trace output destination (see the
86 <<url-format,URL format>> section below).
87
88 [[snapshot-mode]]Snapshot mode::
89 Traces the local system without writing the trace to the local file
90 system (implicit option:--no-output option). Channels are automatically
91 configured to be snapshot-ready on creation (see
92 man:lttng-enable-channel(1)). The man:lttng-snapshot(1)
93 command is used to take snapshots of the current ring buffers.
94 The option:--set-url, or option:--ctrl-url and option:--data-url
95 options set the default snapshot output destination.
96
97 [[live-mode]]Live mode::
98 Traces the local system, sending trace data to an LTTng relay daemon
99 over the network (see man:lttng-relayd(8)). The
100 option:--set-url, or option:--ctrl-url and option:--data-url options
101 set the trace output destination. The live output URLs cannot use
102 the `file://` protocol (see the <<url-format,URL format>>
103 section below).
104
105
106 [[url-format]]
107 URL format
108 ~~~~~~~~~~
109 The option:--set-url, option:--ctrl-url, and option:--data-url options'
110 arguments are URLs.
111
112 The format of those URLs is one of:
113
114 [verse]
115 file://'TRACEPATH'
116 'NETPROTO'://('HOST' | 'IPADDR')[:__CTRLPORT__[:__DATAPORT__]][/'TRACEPATH']
117
118 The `file://` protocol targets the *local file system* and can only
119 be used as the option:--set-url option's argument when the session is
120 created in <<local-mode,local>> or <<snapshot-mode,snapshot>> mode.
121
122 'TRACEPATH'::
123 Absolute path to trace files on the local file system.
124
125 The other version is available when the session is created in
126 <<network-streaming-mode,network streaming>>,
127 <<snapshot-mode,snapshot>>, or <<live-mode,live>> mode.
128
129 'NETPROTO'::
130 Network protocol, amongst:
131 +
132 --
133 `net`::
134 TCP over IPv4; the default values of 'CTRLPORT' and 'DATAPORT'
135 are respectively {default_network_control_port} and
136 {default_network_data_port}.
137
138 `net6`::
139 TCP over IPv6: same default ports as the `net` protocol.
140
141 `tcp`::
142 Same as the `net` protocol; can only be used with the
143 option:--ctrl-url and option:--data-url options together.
144
145 `tcp6`::
146 Same as the `net6` protocol; can only be used with the
147 option:--ctrl-url and option:--data-url options together.
148 --
149
150 ('HOST' | 'IPADDR')::
151 Hostname or IP address (IPv6 address *must* be enclosed in brackets
152 (`[` and `]`); see https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]).
153
154 'CTRLPORT'::
155 Control port.
156
157 'DATAPORT'::
158 Data port.
159
160 'TRACEPATH'::
161 Path of trace files on the remote file system. This path is relative
162 to the base output directory set on the relay daemon side;
163 see man:lttng-relayd(8).
164
165
166 include::common-cmd-options-head.txt[]
167
168
169 Mode selection
170 ~~~~~~~~~~~~~~
171 option:--live[='DELAYUS']::
172 Create the session in <<live-mode,live mode>>.
173 +
174 The optional 'DELAYUS' parameter, given in microseconds, is the
175 maximum time the user can wait for the data to be flushed. This mode
176 can be set with a network URL (options option:--set-url, or
177 option:--ctrl-url and option:--data-url) and must have a relay
178 daemon listening (see man:lttng-relayd(8)).
179 +
180 By default, 'DELAYUS' is {default_lttng_live_timer} and the network URL
181 is set to `net://127.0.0.1`.
182
183 option:--snapshot::
184 Create the session in <<snapshot-mode,snapshot mode>>.
185 This is the equivalent of using the option:--no-output option and
186 creating all the channels of this new tracing session in overwrite
187 mode with an `mmap` output type.
188
189
190 Output
191 ~~~~~~
192 option:--no-output::
193 In <<local-mode,local mode>>, do not output any trace data.
194
195 option:-o 'PATH', option:--output='PATH'::
196 In <<local-mode,local mode>>, set trace output path to 'PATH'.
197
198 option:--shm-path='PATH'::
199 Create shared memory holding buffers at 'PATH'.
200
201
202 URL
203 ~~~
204 See the <<url-format,URL format>> section above for more information
205 about the syntax of the following options' 'URL' argument.
206
207 option:-C 'URL', option:--ctrl-url='URL'::
208 Set control path URL to 'URL' (must use option:--data-url option
209 also).
210
211 option:-D 'URL', option:--data-url='URL'::
212 Set data path URL to 'URL' (must use option:--ctrl-url option
213 also).
214
215 option:-U 'URL', option:--set-url='URL'::
216 Set URL destination of the trace data to 'URL'. It is persistent for
217 the session lifetime. This option sets both data
218 (option:--data-url option) and control (option:--ctrl-url option)
219 URLs at the same time.
220 +
221 In <<local-mode,local>> mode, 'URL' must start with `file://` followed
222 by the destination path on the local file system.
223
224
225 include::common-cmd-help-options.txt[]
226
227
228 include::common-cmd-footer.txt[]
229
230
231 SEE ALSO
232 --------
233 man:lttng-destroy(1),
234 man:lttng-set-session(1),
235 man:lttng(1)
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