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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 | |
f87c4756 | 72 | 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 | ||
83 | Network streaming mode:: | |
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). | |
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89 | |
90 | Snapshot mode:: | |
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 | ||
99 | Live mode:: | |
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 | ||
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120 | The `file://` protocol targets the *local file system* and can only |
121 | be used as the option:--set-url option's argument in _local mode_. | |
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122 | |
123 | 'TRACEPATH':: | |
124 | Absolute path to trace files on the local file system. | |
125 | ||
f87c4756 | 126 | The other version is used for the _network streaming mode_. |
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127 | |
128 | 'NETPROTO':: | |
129 | Network protocol, amongst: | |
130 | + | |
36574617 PP |
131 | -- |
132 | `net`:: | |
133 | TCP over IPv4; the default values of `<ctrl port>` and `<data port>` | |
134 | are resp. 5342 and 5343. | |
135 | ||
136 | `net6`:: | |
137 | TCP over IPv6: same default ports as the `net` protocol. | |
138 | ||
139 | `tcp`:: | |
140 | Same as the `net` protocol; can only be used with the | |
141 | option:--ctrl-url and option:--data-url options together. | |
142 | ||
143 | `tcp6`:: | |
144 | Same as the `net6` protocol; can only be used with the | |
145 | option:--ctrl-url and option:--data-url options together. | |
146 | -- | |
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147 | |
148 | ('HOST' | 'IPADDR'):: | |
149 | Hostname or IP address (IPv6 address *must* be enclosed in brackets | |
150 | (`[` and `]`); see https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]). | |
151 | ||
152 | 'CTRLPORT':: | |
153 | Control port. | |
154 | ||
155 | 'DATAPORT':: | |
156 | Data port. | |
157 | ||
158 | 'TRACEPATH':: | |
159 | Path of trace files on the remote file system. This path is relative | |
160 | to the base output directory set on the relay daemon side; | |
7c1a4458 | 161 | see man:lttng-relayd(8). |
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162 | |
163 | ||
164 | include::common-cmd-options-head.txt[] | |
165 | ||
166 | ||
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167 | Mode selection |
168 | ~~~~~~~~~~~~~~ | |
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169 | option:--live[='DELAYUS']:: |
170 | Create the session in live mode. The optional 'DELAYUS' parameter, | |
171 | given in microseconds, is the maximum time the user can wait for | |
172 | the data to be flushed. This mode can be set with a network URL | |
173 | (options option:--set-url, or option:--ctrl-url and option:--data-url) | |
7c1a4458 | 174 | and must have a relay daemon listening (see man:lttng-relayd(8)). |
ba50d967 | 175 | + |
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176 | By default, 'DELAYUS' is {default_lttng_live_timer} and the network URL |
177 | is set to `net://127.0.0.1`. | |
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178 | |
179 | option:--snapshot:: | |
180 | Create the session in snapshot mode. This is the equivalent of using | |
181 | the option:--no-output option and creating all the channels of this | |
182 | new tracing session in overwrite mode with an `mmap` output type. | |
183 | ||
184 | ||
185 | Output | |
186 | ~~~~~~ | |
187 | option:--no-output:: | |
188 | Do not output any trace data. | |
189 | ||
190 | option:-o, option:--output='PATH':: | |
191 | Set trace output path to 'PATH'. | |
192 | ||
193 | option:--shm-path='PATH':: | |
194 | Create shared memory holding buffers at 'PATH'. | |
195 | ||
196 | ||
197 | URL | |
198 | ~~~ | |
199 | See the <<url-format,URL format>> section above for more information | |
200 | about the syntax of the following options' 'URL' argument. | |
201 | ||
202 | option:-C, option:--ctrl-url='URL':: | |
203 | Set control path URL to 'URL' (must use option:--data-url option | |
204 | also). | |
205 | ||
206 | option:-D, option:--data-url='URL':: | |
207 | Set data path URL to 'URL' (must use option:--ctrl-url option | |
208 | also). | |
209 | ||
210 | option:-U, option:--set-url='URL':: | |
211 | Set URL destination of the trace data to 'URL'. It is persistent for | |
212 | the session lifetime. This option sets both data | |
213 | (option:--data-url option) and control (option:--ctrl-url option) | |
214 | URLs at the same time. | |
215 | ||
216 | ||
217 | include::common-cmd-help-options.txt[] | |
218 | ||
219 | ||
220 | include::common-cmd-footer.txt[] | |
221 | ||
222 | ||
223 | SEE ALSO | |
224 | -------- | |
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225 | man:lttng-destroy(1), |
226 | man:lttng-set-session(1), | |
227 | man:lttng(1) |