1 .TH "LTTNG" "1" "May 13th, 2014" "" ""
4 lttng \(em LTTng 2.x tracer control command line tool
9 lttng [OPTIONS] <COMMAND>
13 The LTTng project aims at providing highly efficient tracing tools for Linux.
14 Its tracers help track down performance issues and debug problems
15 involving multiple concurrent processes and threads. Tracing across multiple
16 systems is also possible.
18 The \fBlttng\fP command line tool from the lttng-tools package is used to control
19 both kernel and user-space tracing. Every interaction with the tracer should
20 be done by this tool or by the liblttng-ctl library provided by the lttng-tools
23 LTTng uses a session daemon (lttng-sessiond(8)), acting as a tracing registry,
24 which allows you to interact with multiple tracers (kernel and user-space)
25 inside the same container, a tracing session. Traces can be gathered from the
26 kernel and/or instrumented applications (lttng-ust(3)). Aggregating and reading
27 those traces is done using the babeltrace(1) text viewer.
29 We introduce the notion of \fBtracing domains\fP which is essentially a type of
30 tracer (kernel, user space, JUL, LOG4J or Python for now). In the future, we
31 could see more tracer like for instance an hypervisor. For some commands,
32 you'll need to specify on which domain the command operates (\-u, \-k, \-l, \-j
33 or \-p). For instance, the kernel domain must be specified when enabling a
36 In order to trace the kernel, the session daemon needs to be running as root.
37 LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
38 in that group can interact with the root session daemon and thus trace the
39 kernel. Session daemons can co-exist, meaning that you can have a session daemon
40 running as Alice that can be used to trace her applications along side with a
41 root daemon or even a Bob daemon. We highly recommend starting the session
42 daemon at boot time for stable and long term tracing.
44 Each user-space application instrumented with lttng-ust(3) will automatically
45 register with the root session daemon and its user session daemon. This allows
46 each daemon to list the available traceable applications and tracepoints at any
47 given moment (See the \fBlist\fP command).
51 This program follow the usual GNU command line syntax with long options starting with
52 two dashes. Below is a summary of the available options.
57 Show summary of possible options and commands.
59 .BR "\-v, \-\-verbose"
61 Three levels of verbosity are available which are triggered by putting additional v to
62 the option (\-vv or \-vvv)
65 Suppress all messages (even errors).
67 .BR "\-g, \-\-group NAME"
68 Set unix tracing group name. (default: tracing)
70 .BR "\-n, \-\-no-sessiond"
71 Don't automatically spawn a session daemon.
73 .BR "\-\-sessiond\-path PATH"
74 Set session daemon full binary path.
76 .BR "\-\-list\-options"
77 Simple listing of lttng options.
79 .BR "\-\-list\-commands"
80 Simple listing of lttng commands.
87 Machine interface (MI) mode converts the traditional pretty printing to a
88 machine output syntax. MI mode provides a format change-resistant way to access
89 information generated via the lttng command line.
91 When using MI mode, the data is printed on \fBstdout\fP. Error and warning are
92 printed on \fBstderr\fP with the pretty print default format.
94 If any errors occur during the execution of a command, the return value of the
95 command will be different than zero. In this case, lttng does NOT guarantee the
96 syntax and data validity of the generated MI output.
98 For XML output type, a schema definition (XSD) file used for validation can be
99 found under src/common/mi_lttng.xsd
104 \fBadd-context\fP [OPTIONS]
106 Add context to event(s) and/or channel(s).
108 A context is basically extra information appended to a channel. For instance,
109 you could ask the tracer to add the PID information for all events in a
110 channel. You can also add performance monitoring unit counters (perf PMU) using
113 For example, this command will add the context information 'prio' and two per-CPU
114 perf counters (hardware branch misses and cache misses), to all events in the trace
118 # lttng add-context \-k \-t prio \-t perf:cpu:branch-misses \\
119 \-t perf:cpu:cache-misses
122 Please take a look at the help (\-h/\-\-help) for a detailed list of available
125 Perf counters are available as per-CPU ("perf:cpu:...") and per-thread
126 ("perf:thread:...") counters. Currently, per-CPU counters can only be
127 used with the kernel tracing domain, and per-thread counters can only be
128 used with the UST tracing domain.
130 If no channel is given (\-c), the context is added to all channels that were
131 already enabled. If the session has no channel, a default channel is created.
132 Otherwise the context will be added only to the given channel (\-c).
134 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
141 Show summary of possible options and commands.
143 .BR "\-s, \-\-session NAME"
144 Apply on session name.
146 .BR "\-c, \-\-channel NAME"
147 Apply on channel name.
149 .BR "\-k, \-\-kernel"
150 Apply for the kernel tracer
152 .BR "\-u, \-\-userspace"
153 Apply for the user-space tracer
155 .BR "\-t, \-\-type TYPE"
156 Context type. You can repeat this option on the command line. Please
157 use "lttng add-context \-h" to list all available types.
162 \fBcalibrate\fP [OPTIONS]
164 Quantify LTTng overhead
166 The LTTng calibrate command can be used to find out the combined average
167 overhead of the LTTng tracer and the instrumentation mechanisms used. This
168 overhead can be calibrated in terms of time or using any of the PMU performance
169 counter available on the system.
171 For now, the only calibration implemented is that of the kernel function
172 instrumentation (kretprobes).
174 * Calibrate kernel function instrumentation
176 Let's use an example to show this calibration. We use an i7 processor with 4
177 general-purpose PMU registers. This information is available by issuing dmesg,
178 looking for "generic registers".
180 This sequence of commands will gather a trace executing a kretprobe hooked on
181 an empty function, gathering PMU counters LLC (Last Level Cache) misses
182 information (see lttng add-context \-\-help to see the list of available PMU
186 # lttng create calibrate-function
187 # lttng enable-event calibrate \-\-kernel \\
188 \-\-function lttng_calibrate_kretprobe
189 # lttng add-context \-\-kernel \-t perf:cpu:LLC-load-misses \\
190 \-t perf:cpu:LLC-store-misses \\
191 \-t perf:cpu:LLC-prefetch-misses
193 # for a in $(seq 1 10); do \\
194 lttng calibrate \-\-kernel \-\-function;
197 # babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
201 The output from babeltrace can be saved to a text file and opened in a
202 spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
203 consecutive "calibrate_entry" and "calibrate_return" events. Note that these
204 counters are per-CPU, so scheduling events would need to be present to account
205 for migration between CPU. Therefore, for calibration purposes, only events
206 staying on the same CPU must be considered.
208 The average result, for the i7, on 10 samples:
212 perf_LLC_load_misses: 5.0 0.577
213 perf_LLC_store_misses: 1.6 0.516
214 perf_LLC_prefetch_misses: 9.0 14.742
217 As we can notice, the load and store misses are relatively stable across runs
218 (their standard deviation is relatively low) compared to the prefetch misses.
219 We can conclude from this information that LLC load and store misses can be
220 accounted for quite precisely, but prefetches within a function seems to behave
221 too erratically (not much causality link between the code executed and the CPU
222 prefetch activity) to be accounted for.
228 Show summary of possible options and commands.
230 .BR "\-k, \-\-kernel"
231 Apply for the kernel tracer
233 .BR "\-u, \-\-userspace"
234 Apply for the user-space tracer
237 Dynamic function entry/return probe (default)
242 \fBcreate\fP [NAME] [OPTIONS]
244 Create tracing session.
246 A tracing session contains channel(s) which contains event(s). It is domain
247 agnostic, meaning that channels and events can be enabled for the
248 user-space tracer and/or the kernel tracer. It acts like a container
249 aggregating multiple tracing sources.
251 On creation, a \fB.lttngrc\fP file is created in your $HOME directory
252 containing the current session name. If NAME is omitted, a session name is
253 automatically created having this form: 'auto-yyyymmdd-hhmmss'.
255 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
258 The $HOME environment variable can be overridden by defining the environment
259 variable LTTNG_HOME. This is useful when the user running the commands has
260 a non-writeable home directory.
262 The session name MUST NOT contain the character '/'.
268 Show summary of possible options and commands.
270 .BR "\-\-list-options"
271 Simple listing of options
273 .BR "\-o, \-\-output PATH"
274 Specify output path for traces
277 Traces will not be output
280 Set the session in snapshot mode. Created in no-output mode and uses the
281 URL, if one is specified, as the default snapshot output. Every channel will be set
282 in overwrite mode and with mmap output (splice not supported).
284 .BR "\-\-live [USEC]"
285 Set the session exclusively in live mode. The parameter is the delay in micro
286 seconds before the data is flushed and streamed. The live mode allows you to
287 stream the trace and view it while it's being recorded by any tracer. For that,
288 you need a lttng-relayd and this session requires a network URL (\-U or
289 \-C/\-D). If no USEC nor URL is provided, the default is to use a timer value
290 set to 1000000 and the network URL set to net://127.0.0.1.
292 To read a live session, you can use babeltrace(1) or the live streaming
293 protocol in doc/live-reading-protocol.txt. Here is an example:
296 $ lttng-relayd -o /tmp/lttng
297 $ lttng create --live 200000 -U net://localhost
298 $ lttng enable-event -a --userspace
302 After the start, you'll be able to read the events while they are being
303 recorded in /tmp/lttng.
306 .BR "\-\-shm-path PATH"
308 Path where shared memory holding buffers should be created. Useful
309 when used with pramfs to extract trace data after crash.
312 .BR "\-U, \-\-set-url=URL"
313 Set URL for the consumer output destination. It is persistent for the
314 session lifetime. Redo the command to change it. This will set both data
315 and control URL for network.
317 .BR "\-C, \-\-ctrl-url=URL"
318 Set control path URL. (Must use -D also)
320 .BR "\-D, \-\-data-url=URL"
321 Set data path URL. (Must use -C also)
323 Using these options, each API call can be controlled individually. For
324 instance, \-C does not enable the consumer automatically. You'll need the \-e
329 proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]
331 Supported protocols are (proto):
334 Local filesystem full path.
338 This will use the default network transport layer which is TCP for both
339 control (PORT1) and data port (PORT2). The default ports are
340 respectively 5342 and 5343. Note that net[6]:// is not yet supported.
344 Can only be used with -C and -D together
346 NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)
351 # lttng create -U net://192.168.1.42
353 Uses TCP and default ports for the given destination.
356 # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]
358 Uses TCP, default ports and IPv6.
361 # lttng create s1 -U net://myhost.com:3229
363 Create session s1 and set its consumer to myhost.com on port 3229 for control.
368 \fBdestroy\fP [NAME] [OPTIONS]
370 Teardown tracing session
372 Free memory on the session daemon and tracer side. It's gone!
374 If NAME is omitted, the session name is taken from the .lttngrc file.
380 Show summary of possible options and commands.
385 .BR "\-\-list-options"
386 Simple listing of options
391 \fBenable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
393 Enable tracing channel
395 To enable an event, you must enable both the event and the channel that
398 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
401 Exactly one of \-k or -u must be specified.
403 It is important to note that if a certain type of buffers is used, the session
404 will be set with that type and all other subsequent channel needs to have the
407 Note that once the session has been started and enabled on the tracer side,
408 it's not possible anymore to enable a new channel for that session.
416 .BR "\-\-list-options"
417 Simple listing of options
419 .BR "\-s, \-\-session NAME"
420 Apply on session name
422 .BR "\-k, \-\-kernel"
423 Apply to the kernel tracer
425 .BR "\-u, \-\-userspace"
426 Apply to the user-space tracer
429 Discard event when subbuffers are full (default)
432 Flight recorder mode: overwrites events when subbuffers are full. The
433 number of subbuffer must be 2 or more.
435 .BR "\-\-subbuf-size SIZE"
436 Subbuffer size in bytes {+k,+M,+G}.
437 (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
438 Rounded up to the next power of 2.
440 The minimum subbuffer size, for each tracer, is the max value between
441 the default above and the system page size. You can issue this command
442 to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
444 .BR "\-\-num-subbuf NUM"
445 Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4,
446 metadata: 2) Rounded up to the next power of 2.
448 .BR "\-\-switch-timer USEC"
449 Switch subbuffer timer interval in µsec.
450 (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
452 .BR "\-\-read-timer USEC"
453 Read timer interval in µsec.
454 (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
456 .BR "\-\-output TYPE"
457 Channel output type. Possible values: mmap, splice
458 (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
460 .BR "\-\-buffers-uid"
461 Use per UID buffer (\-u only). Buffers are shared between applications
462 that have the same UID.
464 .BR "\-\-buffers-pid"
465 Use per PID buffer (\-u only). Each application has its own buffers.
467 .BR "\-\-buffers-global"
468 Use shared buffer for the whole system (\-k only)
470 .BR "\-C, \-\-tracefile-size SIZE"
471 Maximum size of each tracefile within a stream (in bytes).
472 0 means unlimited. (default: 0)
473 Note: traces generated with this option may inaccurately report
474 discarded events as of CTF 1.8.
476 .BR "\-W, \-\-tracefile-count COUNT"
477 Used in conjunction with \-C option, this will limit the number of files
478 created to the specified count. 0 means unlimited. (default: 0)
483 $ lttng enable-channel -k -C 4096 -W 32 chan1
485 For each stream, the maximum size of each trace file will be 4096 bytes and
486 there will be a maximum of 32 different files. The file count is appended after
487 the stream number as seen in the following example. The last trace file is
488 smaller than 4096 since it was not completely filled.
491 ~/lttng-traces/[...]/chan1_0_0 (4096)
492 ~/lttng-traces/[...]/chan1_0_1 (4096)
493 ~/lttng-traces/[...]/chan1_0_2 (3245)
494 ~/lttng-traces/[...]/chan1_1_0 (4096)
499 $ lttng enable-channel -k -C 4096
501 This will create trace files of 4096 bytes and will create new ones as long as
502 there is data available.
507 \fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]
511 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
512 omitted, a default channel named '\fBchannel0\fP' is created and the event is
513 added to it. If \fB\-c, \-\-channel\fP is omitted, but a non-default
514 channel already exists within the session, an error is returned. For the
515 user-space tracer, using \fB\-a, \-\-all\fP is the same as using the
518 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
525 Show summary of possible options and commands.
527 .BR "\-\-list-options"
528 Simple listing of options
530 .BR "\-s, \-\-session NAME"
531 Apply on session name
533 .BR "\-c, \-\-channel NAME"
534 Apply on channel name
537 Enable all tracepoints and syscalls. This actually enables a single
540 .BR "\-k, \-\-kernel"
541 Apply for the kernel tracer
543 .BR "\-u, \-\-userspace"
544 Apply for the user-space tracer
547 Apply for Java application using Java Util Logging interface (JUL)
550 Apply for Java application using LOG4J
552 .BR "\-p, \-\-python"
553 Apply for Python application using the logging module.
556 Tracepoint event (default). Userspace tracer supports wildcards at the end
557 of string. Don't forget to quote to deal with bash expansion.
564 .BR "\-\-loglevel NAME"
565 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
566 For the JUL domain, the loglevel ranges are detailed with the \-\-help
567 option thus starting from SEVERE to FINEST.
568 For the LOG4J domain, loglevels range from FATAL to TRACE which are also
569 detailed in the help.
570 For the Python domain, loglevels range from CRITICAL to DEBUG which are
571 detailed in the help as well.
573 .BR "\-\-loglevel-only NAME"
574 Tracepoint loglevel (only this loglevel).
575 The loglevel or loglevel-only options should be combined with a
576 tracepoint name or tracepoint wildcard.
578 .BR "\-\-probe (addr | symbol | symbol+offset)"
579 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
580 or hexadecimal (0xNNN...)
582 .BR "\-\-function (addr | symbol | symbol+offset)"
583 Dynamic function entry/return probe. Addr and offset can be octal
584 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
587 System call event. Enabling syscalls tracing (kernel tracer), you will
588 not be able to disable them with disable-event. This is a known
589 limitation. You can disable the entire channel to do the trick. Also note
590 that per-syscall selection is not supported yet. Use with "-a" to enable
593 .BR "\-\-filter 'expression'"
594 Set a filter on a newly enabled event. Filter expression on event
595 fields and context. The event will be recorded if the filter's
596 expression evaluates to TRUE. Only specify on first activation of a
597 given event within a session.
598 Specifying a filter is only allowed when enabling events within a session before
599 tracing is started. If the filter fails to link with the event
600 within the traced domain, the event will be discarded.
601 Filtering is currently only implemented for the user-space tracer.
606 'intfield > 500 && intfield < 503'
607 '(strfield == "test" || intfield != 10) && intfield > 33'
608 'doublefield > 1.1 && intfield < 5.3'
611 Wildcards are allowed at the end of strings:
613 In string literals, the escape character is a '\\'. Use '\\*' for
614 the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
615 matches any sequence of characters, including an empty sub-string
616 (matches 0 or more characters).
618 Context information can be used for filtering. The examples below shows
619 usage of context filtering on the process name (using a wildcard), process ID
620 range, and unique thread ID. The process and thread IDs of
621 running applications can be found under columns "PID" and "LWP" of the
625 '$ctx.procname == "demo*"'
626 '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
630 Context information is available to all filters whether or not the add-context
631 command has been used to add it to the event's channel, as long as the context
632 field exists for that domain. For example, the filter examples given above will
633 never fail to link: no add-context is required for the event's channel.
636 .BR "\-x, \-\-exclude LIST"
637 Add exclusions to UST tracepoints:
638 Events that match any of the items in the comma-separated LIST are not
639 enabled, even if they match a wildcard definition of the event.
641 This option is also applicable with the \fB\-a, \-\-all\fP option,
642 in which case all UST tracepoints are enabled except the ones whose
643 names match any of the items in LIST.
648 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
650 Disable tracing channel
652 Disabling a channel disables the tracing of all of the channel's events. A channel
653 can be re-enabled by calling \fBlttng enable-channel NAME\fP again.
655 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
662 Show summary of possible options and commands.
664 .BR "\-\-list-options"
665 Simple listing of options
667 .BR "\-s, \-\-session NAME"
668 Apply on session name
670 .BR "\-k, \-\-kernel"
671 Apply for the kernel tracer
673 .BR "\-u, \-\-userspace"
674 Apply for the user-space tracer
679 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
681 Disable tracing event
683 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
686 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
689 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
690 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
691 exists within the session, an error is returned.
697 Show summary of possible options and commands.
699 .BR "\-\-list-options"
700 Simple listing of options
702 .BR "\-s, \-\-session NAME"
703 Apply on session name
705 .BR "\-c, \-\-channel NAME"
706 Apply on channel name
708 .BR "\-a, \-\-all-events"
709 Disable all events. This does NOT disable "*" but rather every known
710 events of the session.
712 .BR "\-k, \-\-kernel"
713 Apply for the kernel tracer
715 .BR "\-u, \-\-userspace"
716 Apply for the user-space tracer
719 Apply for Java application using Java Util Logging interface (JUL)
722 Apply for Java application using LOG4J
724 .BR "\-p, \-\-python"
725 Apply for Python application using the logging module.
730 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
732 List tracing session information.
734 With no arguments, it will list available tracing session(s).
736 With the session name, it will display the details of the session including
737 the trace file path, the associated channels and their state (activated
738 and deactivated), the activated events and more.
740 With \-k alone, it will list all available kernel events (except the system
742 With \-j alone, the available JUL event from registered application will be
743 list. The event corresponds to the Logger name in the Java JUL application.
744 With \-l alone, the available LOG4J event from registered application will be
745 list. The event corresponds to the Logger name in the Java LOG4J application.
746 With \-p alone, the available Python event from registered application will be
747 list. The event corresponds to the Logger name in the Python application.
748 With \-u alone, it will list all available user-space events from registered
749 applications. Here is an example of 'lttng list \-u':
752 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
753 ust_tests_hello:tptest_sighandler (type: tracepoint)
754 ust_tests_hello:tptest (type: tracepoint)
757 You can now enable any event listed by using the name :
758 \fBust_tests_hello:tptest\fP.
764 Show summary of possible options and commands.
766 .BR "\-\-list-options"
767 Simple listing of options
769 .BR "\-k, \-\-kernel"
772 .BR "\-u, \-\-userspace"
773 Select user-space domain.
776 Apply for Java application using JUL
779 Apply for Java application using LOG4J
781 .BR "\-p, \-\-python"
782 Apply for Python application using the logging module.
784 .BR "\-f, \-\-fields"
791 .BR "\-c, \-\-channel NAME"
792 List details of a channel
794 .BR "\-d, \-\-domain"
795 List available domain(s)
800 \fBload\fP [OPTIONS] [NAME]
802 Load tracing session configuration
804 If NAME is omitted, all session configurations found in both the user's session
805 configuration directory (default: ~/.lttng/sessions/) and the system session
806 configuration directory (default: /etc/lttng/sessions/) will be loaded. Note
807 that the sessions in the user directory are loaded first and then the system
808 wide directory are loaded.
814 Show summary of possible options and commands.
817 Load all session configurations (default).
819 .BR "\-i, \-\-input-path PATH"
820 Specify the input path for session configurations. This overrides the default
821 session configuration directory.
824 Overwrite current session configuration(s) if a session of the same name
830 \fBsave\fP [OPTIONS] [SESSION]
832 Save tracing session configuration
834 If SESSION is omitted, all session configurations will be saved to individual
835 \fB.lttng\fP files under the user's session configuration directory (default:
836 ~/.lttng/sessions/). The default session configuration file naming scheme is
839 For instance, a user in the tracing group saving a session from a root session
840 daemon will save it in her/his user directory.
846 Show summary of possible options and commands.
849 Save all session configurations (default).
851 .BR "\-o, \-\-output-path PATH"
852 Specify the output path for saved sessions. This overrides the default session
853 configuration directory.
856 Overwrite session configuration file if session name clashes.
861 \fBset-session\fP NAME [OPTIONS]
863 Set current session name
865 Will change the session name in the .lttngrc file.
871 Show summary of possible options and commands.
873 .BR "\-\-list-options"
874 Simple listing of options
879 \fBsnapshot\fP [OPTIONS] ACTION
881 Snapshot command for LTTng session.
887 Show summary of possible options and commands.
889 .BR "\-\-list-options"
890 Simple listing of options
896 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
898 Setup and add a snapshot output for a session. Output is the destination
899 where the snapshot will be sent. Only one output is permitted. To change it,
900 you'll need to delete it and add back the new one.
903 \fBdel-output\fP ID | NAME [-s <NAME>]
905 Delete an output for a session using the output's ID. You can either specify the
906 output by name or use its ID as returned by the list-output command.
909 \fBlist-output\fP [-s <NAME>]
911 List the output of a session. Attributes of the output are printed.
914 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
916 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
917 used instead of a previously added output. Specifying only a name or/and a max
918 size will override the current output values. For instance, you can record a
919 snapshot with a custom maximum size or with a different name.
922 $ lttng snapshot add-output -n mysnapshot file:///data/snapshot
924 $ lttng snapshot record -n new_name_snapshot
927 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
928 rather then in mysnapshot*/
931 .B DETAILED ACTION OPTIONS
934 .BR "\-s, \-\-session NAME"
935 Apply to session name.
937 .BR "\-n, \-\-name NAME"
938 Name of the snapshot's output.
940 .BR "\-m, \-\-max-size SIZE"
941 Maximum size in bytes of the snapshot. The maximum size does not include the
942 metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
945 .BR "\-C, \-\-ctrl-url URL"
946 Set control path URL. (Must use -D also)
948 .BR "\-D, \-\-data-url URL"
949 Set data path URL. (Must use -C also)
954 \fBstart\fP [NAME] [OPTIONS]
958 It will start tracing for all tracers for a specific tracing session.
959 If NAME is omitted, the session name is taken from the .lttngrc file.
965 Show summary of possible options and commands.
967 .BR "\-\-list-options"
968 Simple listing of options
973 \fBstop\fP [NAME] [OPTIONS]
977 It will stop tracing for all tracers for a specific tracing session. Before
978 returning, the command checks for data availability meaning that it will wait
979 until the trace is readable for the session. Use \-\-no-wait to avoid this
982 If NAME is omitted, the session name is taken from the .lttngrc file.
988 Show summary of possible options and commands.
990 .BR "\-\-list-options"
991 Simple listing of options
994 Don't wait for data availability.
1001 Show version information
1007 Show summary of possible options and commands.
1009 .BR "\-\-list-options"
1010 Simple listing of options
1015 \fBview\fP [SESSION_NAME] [OPTIONS]
1017 View traces of a tracing session. By default, the babeltrace viewer
1018 will be used for text viewing. If SESSION_NAME is omitted, the session
1019 name is taken from the .lttngrc file.
1027 .BR "\-\-list-options"
1028 Simple listing of options
1030 .BR "\-t, \-\-trace-path PATH"
1031 Trace directory path for the viewer
1033 .BR "\-e, \-\-viewer CMD"
1034 Specify viewer and/or options to use This will completely override the
1035 default viewers so please make sure to specify the full command. The
1036 trace directory path of the session will be appended at the end to the
1041 .SH "JUL/LOG4J DOMAIN"
1043 This section explains the JUL and LOG4J domain where JUL stands for Java Util
1044 Logging. You can use these by using the \fBliblttng-ust-<domain>-jni.so\fP from
1045 the lttng-ust(3) project.
1047 The LTTng Java Agent uses JNI to link the UST tracer to the Java application
1048 that uses the agent. Thus, it behaves similarly to the UST domain (\-u). When
1049 enabling events, you enable a Logger name that will then be mapped to a default
1050 UST tracepoint called \fBlttng_jul:<domain>_event\fP in the
1051 \fBlttng_<domain>_channel\fP. Using the lttng-ctl API, any JUL/LOG4J events
1052 must use the tracepoint event type (same as \-\-tracepoint).
1054 Because of the default immutable channel, the \fBenable-channel\fP command CAN
1055 NOT be used with the JUL and LOG4J domain thus not having any options.
1057 Also, loglevels are supported. Use \fBlttng enable-event \-h\fP to list them.
1058 Wildcards are NOT supported except the "*" meaning all events (same as \-a).
1060 Exactly like the UST domain, if the Java application has the same UID as you,
1061 you can trace it. Same goes for the tracing group accessing root applications.
1063 Finally, you can list every Logger name that are available from registered
1064 applications to the session daemon by using \fBlttng list \-j\fP or \fB\-l\fP.
1066 Here is an example on how to use the JUL domain.
1071 $ lttng create aSession
1072 $ lttng enable-event -s aSession -j MyCustomLoggerName
1076 More information can be found in the lttng-ust documentation, see
1077 java-util-logging.txt
1082 On success 0 is returned and a positive value on error. Value of 1 means a command
1083 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
1084 something went wrong during the command.
1086 Any other value above 10, please refer to
1087 .BR "<lttng/lttng-error.h>"
1088 for a detailed list or use lttng_strerror() to get a human readable string of
1092 .SH "ENVIRONMENT VARIABLES"
1095 Note that all command line options override environment variables.
1099 .IP "LTTNG_SESSIOND_PATH"
1100 Allows one to specify the full session daemon binary path to lttng command line
1101 tool. You can also use \-\-sessiond-path option having the same effect.
1105 .IP "LTTNG_SESSION_CONFIG_XSD_PATH"
1106 Set the path in which the \fBsession.xsd\fP session configuration schema may be
1113 .BR lttng-sessiond(8),
1114 .BR lttng-relayd(8),
1119 If you encounter any issues or usability problem, please report it on our
1120 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
1121 at https://bugs.lttng.org which is a bug tracker.
1127 lttng is distributed under the GNU General Public License version 2. See the file
1128 COPYING for details.
1130 A Web site is available at http://lttng.org for more information on the LTTng
1133 You can also find our git tree at http://git.lttng.org.
1135 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
1137 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
1142 Thanks to Yannick Brosseau without whom this project would never have been so
1143 lean and mean! Also thanks to the Ericsson teams working on tracing which
1144 helped us greatly with detailed bug reports and unusual test cases.
1146 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
1147 maintainer) and Jon Bernard for our Debian packages.
1149 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
1150 Montreal for the LTTng journey.
1155 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
1156 David Goulet. More people have since contributed to it. It is currently
1157 maintained by Jérémie Galarneau <jeremie.galarneau@efficios.com>.