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 <http://lttng.org/> is an open
14 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 babeltrace(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 Resource tracking
190 lttng-track(1)
191 Track specific system resources.
192 lttng-untrack(1)
194 Untrack specific system resources.
195 Miscellaneous
197 lttng-help(1)
198 Display help information about a command.
199 lttng-version(1)
201 Show version information.
202 lttng-view(1)
204 Start trace viewer.
205
207 LTTNG_ABORT_ON_ERROR
208 Set to 1 to abort the process after the first error is encountered.
209 LTTNG_HOME
211 Overrides the $HOME environment variable. Useful when the user
212 running the commands has a non-writable home directory.
213 LTTNG_MAN_BIN_PATH
215 Absolute path to the man pager to use for viewing help information
216 about LTTng commands (using lttng-help(1) or lttng COMMAND --help).
217 LTTNG_SESSION_CONFIG_XSD_PATH
219 Path in which the session.xsd session configuration XML schema may
220 be found.
221 LTTNG_SESSIOND_PATH
223 Full session daemon binary path.
224 The --sessiond-path option has precedence over this environment
226 variable.
227 Note that the lttng-create(1) command can spawn an LTTng session daemon
229 automatically if none is running. See lttng-sessiond(8) for the
230 environment variables influencing the execution of the session daemon.
231
233 $LTTNG_HOME/.lttngrc
234 User LTTng runtime configuration.
235 This is where the per-user current tracing session is stored
237 between executions of lttng(1). The current tracing session can be
238 set with lttng-set-session(1). See lttng-create(1) for more
239 information about tracing sessions.
240 $LTTNG_HOME/lttng-traces
242 Default output directory of LTTng traces. This can be overridden
243 with the --output option of the lttng-create(1) command.
244 $LTTNG_HOME/.lttng
246 User LTTng runtime and configuration directory.
247 $LTTNG_HOME/.lttng/sessions
249 Default location of saved user tracing sessions (see lttng-save(1)
250 and lttng-load(1)).
251 /usr/local/etc/lttng/sessions
253 System-wide location of saved tracing sessions (see lttng-save(1)
254 and lttng-load(1)).
255 Note
257 $LTTNG_HOME defaults to $HOME when not explicitly set.
258
260 0
261 Success
262 1
264 Command error
265 2
267 Undefined command
268 3
270 Fatal error
271 4
273 Command warning (something went wrong during the command)
274
276 If you encounter any issue or usability problem, please report it on
277 the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.
278
280 · LTTng project website <http://lttng.org>
281 · LTTng documentation <http://lttng.org/docs>
283 · Git repositories <http://git.lttng.org>
285 · GitHub organization <http://github.com/lttng>
287 · Continuous integration <http://ci.lttng.org/>
289 · Mailing list <http://lists.lttng.org> for support and development:
291 lttng-dev@lists.lttng.org
292 · IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
294
296 This program is part of the LTTng-tools project.
297 LTTng-tools is distributed under the GNU General Public License version
299 2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the
300 LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file
301 for details.
302
304 Special thanks to Michel Dagenais and the DORSAL laboratory
305 <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal for
306 the LTTng journey.
307 Also thanks to the Ericsson teams working on tracing which helped us
309 greatly with detailed bug reports and unusual test cases.
310
312 LTTng-tools was originally written by Mathieu Desnoyers, Julien
313 Desfossez, and David Goulet. More people have since contributed to it.
314 LTTng-tools is currently maintained by Jérémie Galarneau
316 <mailto:jeremie.galarneau@efficios.com>.
317
319 lttng-sessiond(8), lttng-relayd(8), lttng-crash(1), lttng-ust(3),
320 babeltrace(1)
321LTTng 2.10.7 05/24/2019 LTTNG(1)