7 lttng - LTTng 2 tracer control command-line tool
13 *lttng* [option:--group='GROUP'] [option:--mi='TYPE'] [option:--no-sessiond | option:--sessiond-path='PATH']
14 [option:--quiet | option:-v | option:-vv | option:-vvv] '<<commands,COMMAND>>' ['COMMAND OPTIONS']
19 The http://lttng.org/[_Linux Trace Toolkit: next generation_] is an open
20 source software package used for correlated tracing of the Linux kernel,
21 user applications, and user libraries.
23 LTTng consists of Linux kernel modules (for Linux kernel tracing) and
24 dynamically loaded libraries (for user application and library tracing).
26 An LTTng _session daemon_, linklttng:lttng-sessiond(8), receives
27 commands from the command-line interface `lttng` to control the LTTng
28 tracers. All interactions with the LTTng tracers happen through the
29 `lttng` tool or through the liblttng-ctl library shipped with the
32 A _tracing domain_ is a tracer category. There are five available
33 domains. For some commands, the domain needs to be specified with a
34 command-line option. The domain options are:
36 nloption:-j, nloption:--jul::
37 Apply command to the `java.util.logging` (JUL) domain.
39 nloption:-k, nloption:--kernel::
40 Apply command to the Linux kernel domain.
42 nloption:-l, nloption:--log4j::
43 Apply command to the Apache log4j 1.2 (Java) domain.
45 nloption:-p, nloption:--python::
46 Apply command to the Python domain.
48 nloption:-u, nloption:--userspace::
49 Apply command to the user space domain.
51 The LTTng session daemon is a tracing registry which allows the user to
52 interact with multiple tracers (kernel and user space) within the same
53 container, a _tracing session_. Traces can be gathered from the Linux
54 kernel and/or from instrumented applications (see
55 linklttng:lttng-ust(3)). You can aggregate and read the events of LTTng
56 traces using linklttng:babeltrace(1).
58 To trace the Linux kernel, the session daemon needs to be running as
59 `root`. LTTng uses a _tracing group_ to allow specific users to interact
60 with the root session daemon. The default tracing group name is
61 `tracing`. You can use the option:--group option to set the tracing
64 Session daemons can coexist. You can have a session daemon running as
65 user Alice that can be used to trace her applications alongside a root
66 session daemon or a session daemon running as user Bob.
68 NOTE: It is highly recommended to start the session daemon at boot time
69 for stable and long-term tracing.
71 User applications instrumented with LTTng automatically register to the
72 root session daemon and to user session daemons. This allows any session
73 daemon to list the available traceable applications and event sources
74 (see linklttng:lttng-list(1)).
76 By default, the linklttng:lttng-create(1) command automatically spawns a
77 user session daemon if none is currently running. The
78 option:--no-sessiond general option can be set to avoid this.
83 option:-g, option:--group='GROUP'::
84 Use 'GROUP' as Unix tracing group (default: `tracing`).
86 option:-m, option:--mi='TYPE'::
87 Print the command's result using the machine interface type 'TYPE'
88 instead of a human-readable output.
90 Supported types: `xml`.
92 The machine interface (MI) mode converts the traditional pretty-printing
93 to a machine output syntax. The MI mode provides a change-resistant way
94 to access information generated by the `lttng` command-line program.
96 When using the MI mode, the data is printed to the standard output.
97 Errors and warnings are printed on the standard error with the
98 pretty-print default format.
100 If any error occurs during the execution of a command, the return value
101 of the command will be different than 0. In this case, `lttng` does
102 :not: guarantee the syntax and data validity of the generated MI output.
104 For the `xml` MI type, an XML schema definition (XSD) file used for
105 validation is available: see the `src/common/mi_lttng.xsd` file in
106 the LTTng-tools source tree.
108 option:-n, option:--no-sessiond::
109 Do not automatically spawn a session daemon.
111 option:-q, option:--quiet::
112 Suppress all messages, including warnings and errors.
114 option:--sessiond-path='PATH'::
115 Set the session daemon binary's absolute path to 'PATH'.
117 option:-v, option:--verbose::
120 Three levels of verbosity are available, which are triggered by
121 appending additional `v` letters to the option
122 (that is, `-vv` and `-vvv`).
127 option:-h, option:--help::
130 option:--list-commands::
131 List available commands.
133 option:--list-options::
134 List available general options.
136 option:-V, option:--version::
143 The following commands also have their own nloption:--help option.
148 linklttng:lttng-create(1)::
149 Create a tracing session.
151 linklttng:lttng-destroy(1)::
152 Tear down tracing sessions.
154 linklttng:lttng-load(1)::
155 Load tracing session configurations.
157 linklttng:lttng-metadata(1)::
158 Manage an LTTng tracing session's metadata generation.
160 linklttng:lttng-save(1)::
161 Save tracing session configurations.
163 linklttng:lttng-set-session(1)::
164 Set current tracing session.
169 linklttng:lttng-add-context(1)::
170 Add context fields to a channel.
172 linklttng:lttng-disable-channel(1)::
173 Disable tracing channels.
175 linklttng:lttng-enable-channel(1)::
176 Create or enable tracing channels.
181 linklttng:lttng-disable-event(1)::
184 linklttng:lttng-enable-event(1)::
185 Create or enable event rules.
190 linklttng:lttng-list(1)::
191 List tracing sessions, domains, channels, and events.
193 linklttng:lttng-status(1)::
194 Get the status of the current tracing session.
199 linklttng:lttng-snapshot(1)::
200 Snapshot buffers of current tracing session.
202 linklttng:lttng-start(1)::
205 linklttng:lttng-stop(1)::
211 linklttng:lttng-track(1)::
212 Track specific system resources.
214 linklttng:lttng-untrack(1)::
215 Untrack specific system resources.
220 linklttng:lttng-calibrate(1)::
221 Quantify LTTng overhead.
223 linklttng:lttng-help(1)::
224 Display help information about a command.
226 linklttng:lttng-version(1)::
227 Show version information.
229 linklttng:lttng-view(1)::
233 include::common-cmd-footer.txt[]
238 linklttng:lttng-sessiond(8),
239 linklttng:lttng-relayd(8),
240 linklttng:lttng-crash(1),
241 linklttng:lttng-ust(3),
242 linklttng:babeltrace(1)