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1 | lttng-create(1) |
2 | =============== | |
3 | ||
4 | ||
5 | NAME | |
6 | ---- | |
7 | lttng-create - Create an LTTng tracing session | |
8 | ||
9 | ||
10 | SYNOPSIS | |
11 | -------- | |
f87c4756 | 12 | Local mode: |
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13 | |
14 | [verse] | |
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15 | *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* [option:--shm-path='PATH'] |
16 | [option:--no-output | option:--output='PATH' | option:--set-url=file://'PATH'] ['SESSION'] | |
17 | ||
18 | Network streaming mode: | |
19 | ||
20 | [verse] | |
21 | *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* [option:--shm-path='PATH'] | |
22 | (option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL') ['SESSION'] | |
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23 | |
24 | Snapshot mode: | |
25 | ||
26 | [verse] | |
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27 | *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* option:--snapshot [option:--shm-path='PATH'] |
28 | [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL'] ['SESSION'] | |
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29 | |
30 | Live mode: | |
31 | ||
32 | [verse] | |
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33 | *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* option:--live[='DELAYUS'] [option:--shm-path='PATH'] |
34 | [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL'] ['SESSION'] | |
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35 | |
36 | ||
37 | DESCRIPTION | |
38 | ----------- | |
39 | The `lttng create` command creates a new tracing session. | |
40 | ||
41 | A tracing session is a named container of channels, which in turn | |
42 | contain event rules. It is domain-agnostic, in that channels and event | |
43 | rules can be enabled for the user space tracer and/or the Linux | |
44 | kernel tracer. | |
45 | ||
46 | On execution, an `.lttngrc` file is created, if it does not exist, in the | |
47 | user's home directory. This file contains the name of the current tracing | |
48 | session. When creating a new tracing session with `lttng create`, the | |
49 | current tracing session is set to this new tracing session. The | |
7c1a4458 | 50 | man:lttng-set-session(1) command can be used to set the current |
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51 | tracing session without manually editing the `.lttngrc` file. |
52 | ||
53 | If 'SESSION' is omitted, a session name is automatically created having | |
54 | this form: `auto-YYYYmmdd-HHMMSS`. 'SESSION' *must not* contain the | |
55 | character `/`. | |
56 | ||
57 | The option:--shm-path option can be used to specify the path to the | |
58 | shared memory holding the ring buffers. Specifying a location on an | |
59 | NVRAM file system makes it possible to retrieve the latest recorded | |
60 | trace data when the system reboots after a crash. To view the events | |
61 | of ring buffer files after a system crash, use the | |
7c1a4458 | 62 | man:lttng-crash(1) utility. |
ba50d967 | 63 | |
7c1a4458 | 64 | Tracing sessions are destroyed using the man:lttng-destroy(1) |
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65 | command. |
66 | ||
67 | ||
68 | Creation modes | |
69 | ~~~~~~~~~~~~~~ | |
f87c4756 | 70 | There are four tracing session modes: |
ba50d967 | 71 | |
948f0a2e | 72 | [[local-mode]]Local mode:: |
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73 | Traces the local system and writes the trace to the local |
74 | file system. The option:--output option specifies the trace path. | |
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75 | Using option:--set-url=file://'PATH' is the equivalent of using |
76 | option:--output='PATH'. The file system output can be disabled using | |
77 | the option:--no-output option. | |
78 | + | |
79 | If none of the options mentioned above are used, then the trace is | |
80 | written locally in the `$LTTNG_HOME/lttng-traces` directory | |
81 | (`$LTTNG_HOME` defaults to `$HOME`). | |
82 | ||
948f0a2e | 83 | [[network-streaming-mode]]Network streaming mode:: |
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84 | Traces the local system and sends the trace over the network to |
85 | a listening relay daemon (see man:lttng-relayd(8)). | |
86 | The option:--set-url, or option:--ctrl-url and option:--data-url | |
87 | options set the trace output destination (see the | |
88 | <<url-format,URL format>> section below). | |
ba50d967 | 89 | |
948f0a2e | 90 | [[snapshot-mode]]Snapshot mode:: |
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91 | Traces the local system without writing the trace to the local file |
92 | system (implicit option:--no-output option). Channels are automatically | |
93 | configured to be snapshot-ready on creation (see | |
7c1a4458 | 94 | man:lttng-enable-channel(1)). The man:lttng-snapshot(1) |
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95 | command is used to take snapshots of the current ring buffers. |
96 | The option:--set-url, or option:--ctrl-url and option:--data-url | |
97 | options set the default snapshot output destination. | |
98 | ||
948f0a2e | 99 | [[live-mode]]Live mode:: |
ba50d967 | 100 | Traces the local system, sending trace data to an LTTng relay daemon |
7c1a4458 | 101 | over the network (see man:lttng-relayd(8)). The |
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102 | option:--set-url, or option:--ctrl-url and option:--data-url options |
103 | set the trace output destination. The live output URLs cannot use | |
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104 | the `file://` protocol (see the <<url-format,URL format>> |
105 | section below). | |
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106 | |
107 | ||
108 | [[url-format]] | |
109 | URL format | |
110 | ~~~~~~~~~~ | |
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111 | The option:--set-url, option:--ctrl-url, and option:--data-url options' |
112 | arguments are URLs. | |
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113 | |
114 | The format of those URLs is one of: | |
115 | ||
116 | [verse] | |
117 | file://'TRACEPATH' | |
118 | 'NETPROTO'://('HOST' | 'IPADDR')[:__CTRLPORT__[:__DATAPORT__]][/'TRACEPATH'] | |
119 | ||
f87c4756 | 120 | The `file://` protocol targets the *local file system* and can only |
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121 | be used as the option:--set-url option's argument when the session is |
122 | created in <<local-mode,local>> or <<snapshot-mode,snapshot>> mode. | |
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123 | |
124 | 'TRACEPATH':: | |
125 | Absolute path to trace files on the local file system. | |
126 | ||
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127 | The other version is available when the session is created in |
128 | <<network-streaming-mode,network streaming>>, | |
129 | <<snapshot-mode,snapshot>>, or <<live-mode,live>> mode. | |
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130 | |
131 | 'NETPROTO':: | |
132 | Network protocol, amongst: | |
133 | + | |
36574617 PP |
134 | -- |
135 | `net`:: | |
1f5cd9d5 | 136 | TCP over IPv4; the default values of 'CTRLPORT' and 'DATAPORT' |
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137 | are respectively {default_network_control_port} and |
138 | {default_network_data_port}. | |
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139 | |
140 | `net6`:: | |
141 | TCP over IPv6: same default ports as the `net` protocol. | |
142 | ||
143 | `tcp`:: | |
144 | Same as the `net` protocol; can only be used with the | |
145 | option:--ctrl-url and option:--data-url options together. | |
146 | ||
147 | `tcp6`:: | |
148 | Same as the `net6` protocol; can only be used with the | |
149 | option:--ctrl-url and option:--data-url options together. | |
150 | -- | |
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151 | |
152 | ('HOST' | 'IPADDR'):: | |
153 | Hostname or IP address (IPv6 address *must* be enclosed in brackets | |
154 | (`[` and `]`); see https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]). | |
155 | ||
156 | 'CTRLPORT':: | |
157 | Control port. | |
158 | ||
159 | 'DATAPORT':: | |
160 | Data port. | |
161 | ||
162 | 'TRACEPATH':: | |
163 | Path of trace files on the remote file system. This path is relative | |
164 | to the base output directory set on the relay daemon side; | |
7c1a4458 | 165 | see man:lttng-relayd(8). |
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166 | |
167 | ||
168 | include::common-cmd-options-head.txt[] | |
169 | ||
170 | ||
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171 | Mode selection |
172 | ~~~~~~~~~~~~~~ | |
ba50d967 | 173 | option:--live[='DELAYUS']:: |
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174 | Create the session in <<live-mode,live mode>>. |
175 | + | |
176 | The optional 'DELAYUS' parameter, given in microseconds, is the | |
177 | maximum time the user can wait for the data to be flushed. This mode | |
178 | can be set with a network URL (options option:--set-url, or | |
179 | option:--ctrl-url and option:--data-url) and must have a relay | |
180 | daemon listening (see man:lttng-relayd(8)). | |
ba50d967 | 181 | + |
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182 | By default, 'DELAYUS' is {default_lttng_live_timer} and the network URL |
183 | is set to `net://127.0.0.1`. | |
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184 | |
185 | option:--snapshot:: | |
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186 | Create the session in <<snapshot-mode,snapshot mode>>. |
187 | This is the equivalent of using the option:--no-output option and | |
188 | creating all the channels of this new tracing session in overwrite | |
189 | mode with an `mmap` output type. | |
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190 | |
191 | ||
192 | Output | |
193 | ~~~~~~ | |
194 | option:--no-output:: | |
948f0a2e | 195 | In <<local-mode,local mode>>, do not output any trace data. |
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196 | |
197 | option:-o, option:--output='PATH':: | |
948f0a2e | 198 | In <<local-mode,local mode>>, set trace output path to 'PATH'. |
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199 | |
200 | option:--shm-path='PATH':: | |
201 | Create shared memory holding buffers at 'PATH'. | |
202 | ||
203 | ||
204 | URL | |
205 | ~~~ | |
206 | See the <<url-format,URL format>> section above for more information | |
207 | about the syntax of the following options' 'URL' argument. | |
208 | ||
209 | option:-C, option:--ctrl-url='URL':: | |
210 | Set control path URL to 'URL' (must use option:--data-url option | |
211 | also). | |
212 | ||
213 | option:-D, option:--data-url='URL':: | |
214 | Set data path URL to 'URL' (must use option:--ctrl-url option | |
215 | also). | |
216 | ||
217 | option:-U, option:--set-url='URL':: | |
218 | Set URL destination of the trace data to 'URL'. It is persistent for | |
219 | the session lifetime. This option sets both data | |
220 | (option:--data-url option) and control (option:--ctrl-url option) | |
221 | URLs at the same time. | |
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222 | + |
223 | In <<local-mode,local>> mode, 'URL' must start with `file://` followed | |
224 | by the destination path on the local file system. | |
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225 | |
226 | ||
227 | include::common-cmd-help-options.txt[] | |
228 | ||
229 | ||
230 | include::common-cmd-footer.txt[] | |
231 | ||
232 | ||
233 | SEE ALSO | |
234 | -------- | |
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235 | man:lttng-destroy(1), |
236 | man:lttng-set-session(1), | |
237 | man:lttng(1) |