1LTTNG(1) LTTng Manual LTTNG(1)
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6 lttng - LTTng 2 tracer control command-line tool
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9 lttng [--group=GROUP] [--mi=TYPE] [--no-sessiond | --sessiond-path=PATH]
10 [--quiet | -v | -vv | -vvv] COMMAND [COMMAND OPTIONS]
11
13 The Linux Trace Toolkit: next generation <https://lttng.org/> is an
14 open source software package used for correlated tracing of the Linux
15 kernel, user applications, and user libraries.
16 LTTng consists of Linux kernel modules (for Linux kernel tracing) and
18 dynamically loaded libraries (for user application and library
19 tracing).
20 An LTTng session daemon, lttng-sessiond(8), receives commands from the
22 command-line interface lttng to control the LTTng tracers. All
23 interactions with the LTTng tracers happen through the lttng tool or
24 through the liblttng-ctl library shipped with the LTTng-tools package.
25 A tracing domain is a tracer category. There are five available
27 domains. For some commands, the domain needs to be specified with a
28 command-line option. The domain options are:
29 -j, --jul
31 Apply command to the java.util.logging (JUL) domain.
32 -k, --kernel
34 Apply command to the Linux kernel domain.
35 -l, --log4j
37 Apply command to the Apache log4j 1.2
38 <https://logging.apache.org/log4j/1.2/> (Java) domain.
39 -p, --python
41 Apply command to the Python <https://www.python.org/> domain.
42 -u, --userspace
44 Apply command to the user space domain (application using
45 liblttng-ust directly; see lttng-ust(3)).
46 The LTTng session daemon is a tracing registry which allows the user to
48 interact with multiple tracers (kernel and user space) within the same
49 container, a tracing session. Traces can be gathered from the Linux
50 kernel and/or from instrumented applications (see lttng-ust(3)). You
51 can aggregate and read the events of LTTng traces using babeltrace2(1).
52 To trace the Linux kernel, the session daemon needs to be running as
54 root. LTTng uses a tracing group to allow specific users to interact
55 with the root session daemon. The default tracing group name is
56 tracing. You can use the --group option to set the tracing group name
57 to use.
58 Session daemons can coexist. You can have a session daemon running as
60 user Alice that can be used to trace her applications alongside a root
61 session daemon or a session daemon running as user Bob.
62 Note
64 It is highly recommended to start the session daemon at boot time
65 for stable and long-term tracing.
66 User applications instrumented with LTTng automatically register to the
68 root session daemon and to user session daemons. This allows any
69 session daemon to list the available traceable applications and event
70 sources (see lttng-list(1)).
71 By default, the lttng-create(1) command automatically spawns a user
73 session daemon if none is currently running. The --no-sessiond general
74 option can be set to avoid this.
75
77 -g GROUP, --group=GROUP
78 Use GROUP as Unix tracing group (default: tracing).
79 -m TYPE, --mi=TYPE
81 Print the command’s result using the machine interface type TYPE
82 instead of a human-readable output.
83 Supported types: xml.
85 The machine interface (MI) mode converts the traditional
87 pretty-printing to a machine output syntax. The MI mode provides a
88 change-resistant way to access information generated by the lttng
89 command-line program.
90 When using the MI mode, the data is printed to the standard output.
92 Errors and warnings are printed on the standard error with the
93 pretty-print default format.
94 If any error occurs during the execution of a command, the return
96 value of the command will be different than 0. In this case, lttng
97 does NOT guarantee the syntax and data validity of the generated MI
98 output.
99 For the xml MI type, an XML schema definition (XSD) file used for
101 validation is available: see the src/common/mi_lttng.xsd file in
102 the LTTng-tools source tree.
103 -n, --no-sessiond
105 Do not automatically spawn a session daemon.
106 -q, --quiet
108 Suppress all messages, including warnings and errors.
109 --sessiond-path=PATH
111 Set the session daemon binary’s absolute path to PATH.
112 -v, --verbose
114 Increase verbosity.
115 Three levels of verbosity are available, which are triggered by
117 appending additional v letters to the option (that is, -vv and
118 -vvv).
119 Program information
121 -h, --help
122 Show help.
123 --list-commands
125 List available commands.
126 --list-options
128 List available general options.
129 -V, --version
131 Show version.
132
134 The following commands also have their own --help option.
135 Tracing sessions
137 lttng-create(1)
138 Create a tracing session.
139 lttng-destroy(1)
141 Tear down tracing sessions.
142 lttng-load(1)
144 Load tracing session configurations.
145 lttng-regenerate(1)
147 Manage an LTTng tracing session’s data regeneration.
148 lttng-save(1)
150 Save tracing session configurations.
151 lttng-set-session(1)
153 Set current tracing session.
154 Channels
156 lttng-add-context(1)
157 Add context fields to a channel.
158 lttng-disable-channel(1)
160 Disable tracing channels.
161 lttng-enable-channel(1)
163 Create or enable tracing channels.
164 Event rules
166 lttng-disable-event(1)
167 Disable event rules.
168 lttng-enable-event(1)
170 Create or enable event rules.
171 Status
173 lttng-list(1)
174 List tracing sessions, domains, channels, and events.
175 lttng-status(1)
177 Get the status of the current tracing session.
178 Control
180 lttng-snapshot(1)
181 Snapshot buffers of current tracing session.
182 lttng-start(1)
184 Start tracing.
185 lttng-stop(1)
187 Stop tracing.
188 Tracing session rotation
190 lttng-disable-rotation(1)
191 Unset a rotation schedule.
192 lttng-enable-rotation(1)
194 Set a rotation schedule.
195 lttng-rotate(1)
197 Archive a tracing session’s current trace chunk.
198 Resource tracking
200 lttng-track(1)
201 Track specific system resources.
202 lttng-untrack(1)
204 Untrack specific system resources.
205 Miscellaneous
207 lttng-help(1)
208 Display help information about a command.
209 lttng-version(1)
211 Show version information.
212 lttng-view(1)
214 Start trace viewer.
215
217 LTTNG_ABORT_ON_ERROR
218 Set to 1 to abort the process after the first error is encountered.
219 LTTNG_HOME
221 Overrides the $HOME environment variable. Useful when the user
222 running the commands has a non-writable home directory.
223 LTTNG_MAN_BIN_PATH
225 Absolute path to the man pager to use for viewing help information
226 about LTTng commands (using lttng-help(1) or lttng COMMAND --help).
227 LTTNG_SESSION_CONFIG_XSD_PATH
229 Path in which the session.xsd session configuration XML schema may
230 be found.
231 LTTNG_SESSIOND_PATH
233 Full session daemon binary path.
234 The --sessiond-path option has precedence over this environment
236 variable.
237 Note that the lttng-create(1) command can spawn an LTTng session daemon
239 automatically if none is running. See lttng-sessiond(8) for the
240 environment variables influencing the execution of the session daemon.
241
243 $LTTNG_HOME/.lttngrc
244 User LTTng runtime configuration.
245 This is where the per-user current tracing session is stored
247 between executions of lttng(1). The current tracing session can be
248 set with lttng-set-session(1). See lttng-create(1) for more
249 information about tracing sessions.
250 $LTTNG_HOME/lttng-traces
252 Default output directory of LTTng traces. This can be overridden
253 with the --output option of the lttng-create(1) command.
254 $LTTNG_HOME/.lttng
256 User LTTng runtime and configuration directory.
257 $LTTNG_HOME/.lttng/sessions
259 Default location of saved user tracing sessions (see lttng-save(1)
260 and lttng-load(1)).
261 /usr/local/etc/lttng/sessions
263 System-wide location of saved tracing sessions (see lttng-save(1)
264 and lttng-load(1)).
265 Note
267 $LTTNG_HOME defaults to $HOME when not explicitly set.
268
270 0
271 Success
272 1
274 Command error
275 2
277 Undefined command
278 3
280 Fatal error
281 4
283 Command warning (something went wrong during the command)
284
286 If you encounter any issue or usability problem, please report it on
287 the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.
288
290 • LTTng project website <https://lttng.org>
291 • LTTng documentation <https://lttng.org/docs>
293 • Git repositories <http://git.lttng.org>
295 • GitHub organization <http://github.com/lttng>
297 • Continuous integration <http://ci.lttng.org/>
299 • Mailing list <http://lists.lttng.org> for support and development:
301 lttng-dev@lists.lttng.org
302 • IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
304
306 This program is part of the LTTng-tools project.
307 LTTng-tools is distributed under the GNU General Public License version
309 2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the
310 LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file
311 for details.
312
314 Special thanks to Michel Dagenais and the DORSAL laboratory
315 <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for
316 the LTTng journey.
317 Also thanks to the Ericsson teams working on tracing which helped us
319 greatly with detailed bug reports and unusual test cases.
320
322 lttng-sessiond(8), lttng-relayd(8), lttng-crash(1), lttng-ust(3),
323 babeltrace2(1)
324LTTng 2.12.4 16 October 2019 LTTNG(1)