1 .TH "LTTNG" "1" "February 05th, 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 or JUL for now). In the future, we could see more
31 tracer like for instance an hypervisor. For some commands, you'll need to
32 specify on which domain the command operates (\-u, \-k or \-j). For instance,
33 the kernel domain must be specified when enabling a kernel event.
35 In order to trace the kernel, the session daemon needs to be running as root.
36 LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
37 in that group can interact with the root session daemon and thus trace the
38 kernel. Session daemons can co-exist, meaning that you can have a session daemon
39 running as Alice that can be used to trace her applications along side with a
40 root daemon or even a Bob daemon. We highly recommend starting the session
41 daemon at boot time for stable and long term tracing.
43 Each user-space application instrumented with lttng-ust(3) will automatically
44 register with the root session daemon and its user session daemon. This allows
45 each daemon to list the available traceable applications and tracepoints at any
46 given moment (See the \fBlist\fP command).
50 This program follow the usual GNU command line syntax with long options starting with
51 two dashes. Below is a summary of the available options.
56 Show summary of possible options and commands.
58 .BR "\-v, \-\-verbose"
60 Three levels of verbosity are available which are triggered by putting additional v to
61 the option (\-vv or \-vvv)
64 Suppress all messages (even errors).
66 .BR "\-g, \-\-group NAME"
67 Set unix tracing group name. (default: tracing)
69 .BR "\-n, \-\-no-sessiond"
70 Don't automatically spawn a session daemon.
72 .BR "\-\-sessiond\-path PATH"
73 Set session daemon full binary path.
75 .BR "\-\-list\-options"
76 Simple listing of lttng options.
78 .BR "\-\-list\-commands"
79 Simple listing of lttng commands.
83 \fBadd-context\fP [OPTIONS]
85 Add context to event(s) and/or channel(s).
87 A context is basically extra information appended to a channel. For instance,
88 you could ask the tracer to add the PID information for all events in a
89 channel. You can also add performance monitoring unit counters (perf PMU) using
92 For example, this command will add the context information 'prio' and two perf
93 counters (hardware branch misses and cache misses), to all events in the trace
97 # lttng add-context \-k \-t prio \-t perf:branch-misses \\
101 Please take a look at the help (\-h/\-\-help) for a detailed list of available
104 If no channel is given (\-c), the context is added to all channels that were
105 already enabled. If the session has no channel, a default channel is created.
106 Otherwise the context will be added only to the given channel (\-c).
108 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
115 Show summary of possible options and commands.
117 .BR "\-s, \-\-session NAME"
118 Apply on session name.
120 .BR "\-c, \-\-channel NAME"
121 Apply on channel name.
123 .BR "\-k, \-\-kernel"
124 Apply for the kernel tracer
126 .BR "\-u, \-\-userspace"
127 Apply for the user-space tracer
129 .BR "\-t, \-\-type TYPE"
130 Context type. You can repeat this option on the command line. Please
131 use "lttng add-context \-h" to list all available types.
136 \fBcalibrate\fP [OPTIONS]
138 Quantify LTTng overhead
140 The LTTng calibrate command can be used to find out the combined average
141 overhead of the LTTng tracer and the instrumentation mechanisms used. This
142 overhead can be calibrated in terms of time or using any of the PMU performance
143 counter available on the system.
145 For now, the only calibration implemented is that of the kernel function
146 instrumentation (kretprobes).
148 * Calibrate kernel function instrumentation
150 Let's use an example to show this calibration. We use an i7 processor with 4
151 general-purpose PMU registers. This information is available by issuing dmesg,
152 looking for "generic registers".
154 This sequence of commands will gather a trace executing a kretprobe hooked on
155 an empty function, gathering PMU counters LLC (Last Level Cache) misses
156 information (see lttng add-context \-\-help to see the list of available PMU
160 # lttng create calibrate-function
161 # lttng enable-event calibrate \-\-kernel \\
162 \-\-function lttng_calibrate_kretprobe
163 # lttng add-context \-\-kernel \-t perf:LLC-load-misses \\
164 \-t perf:LLC-store-misses \\
165 \-t perf:LLC-prefetch-misses
167 # for a in $(seq 1 10); do \\
168 lttng calibrate \-\-kernel \-\-function;
171 # babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
175 The output from babeltrace can be saved to a text file and opened in a
176 spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
177 consecutive "calibrate_entry" and "calibrate_return" events. Note that these
178 counters are per-CPU, so scheduling events would need to be present to account
179 for migration between CPU. Therefore, for calibration purposes, only events
180 staying on the same CPU must be considered.
182 The average result, for the i7, on 10 samples:
186 perf_LLC_load_misses: 5.0 0.577
187 perf_LLC_store_misses: 1.6 0.516
188 perf_LLC_prefetch_misses: 9.0 14.742
191 As we can notice, the load and store misses are relatively stable across runs
192 (their standard deviation is relatively low) compared to the prefetch misses.
193 We can conclude from this information that LLC load and store misses can be
194 accounted for quite precisely, but prefetches within a function seems to behave
195 too erratically (not much causality link between the code executed and the CPU
196 prefetch activity) to be accounted for.
202 Show summary of possible options and commands.
204 .BR "\-k, \-\-kernel"
205 Apply for the kernel tracer
207 .BR "\-u, \-\-userspace"
208 Apply for the user-space tracer
211 Dynamic function entry/return probe (default)
216 \fBcreate\fP [NAME] [OPTIONS]
218 Create tracing session.
220 A tracing session contains channel(s) which contains event(s). It is domain
221 agnostic, meaning that channels and events can be enabled for the
222 user-space tracer and/or the kernel tracer. It acts like a container
223 aggregating multiple tracing sources.
225 On creation, a \fB.lttngrc\fP file is created in your $HOME directory
226 containing the current session name. If NAME is omitted, a session name is
227 automatically created having this form: 'auto-yyyymmdd-hhmmss'.
229 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
232 The $HOME environment variable can be overridden by defining the environment
233 variable LTTNG_HOME. This is useful when the user running the commands has
234 a non-writeable home directory.
236 The session name MUST NOT contain the character '/'.
242 Show summary of possible options and commands.
244 .BR "\-\-list-options"
245 Simple listing of options
247 .BR "\-o, \-\-output PATH"
248 Specify output path for traces
251 Traces will not be output
254 Set the session in snapshot mode. Created in no-output mode and uses the
255 URL, if one is specified, as the default snapshot output. Every channel will be set
256 in overwrite mode and with mmap output (splice not supported).
258 .BR "\-\-live [USEC]"
259 Set the session exclusively in live mode. The paremeter is the delay in micro
260 seconds before the data is flushed and streamed. The live mode allows you to
261 stream the trace and view it while it's being recorded by any tracer. For that,
262 you need a lttng-relayd and this session requires a network URL (\-U or
263 \-C/\-D). If no USEC nor URL is provided, the default is to use a timer value
264 set to 1000000 and the network URL set to net://127.0.0.1.
266 To read a live session, you can use babeltrace(1) or the live streaming
267 protocol in doc/live-reading-protocol.txt. Here is an example:
270 $ lttng-relayd -o /tmp/lttng
271 $ lttng create --live 200000 -U net://localhost
272 $ lttng enable-event -a --userspace
276 After the start, you'll be able to read the events while they are being
277 recorded in /tmp/lttng.
280 .BR "\-U, \-\-set-url=URL"
281 Set URL for the consumer output destination. It is persistent for the
282 session lifetime. Redo the command to change it. This will set both data
283 and control URL for network.
285 .BR "\-C, \-\-ctrl-url=URL"
286 Set control path URL. (Must use -D also)
288 .BR "\-D, \-\-data-url=URL"
289 Set data path URL. (Must use -C also)
291 Using these options, each API call can be controlled individually. For
292 instance, \-C does not enable the consumer automatically. You'll need the \-e
297 proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]
299 Supported protocols are (proto):
302 Local filesystem full path.
306 This will use the default network transport layer which is TCP for both
307 control (PORT1) and data port (PORT2). The default ports are
308 respectively 5342 and 5343. Note that net[6]:// is not yet supported.
312 Can only be used with -C and -D together
314 NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)
319 # lttng create -U net://192.168.1.42
321 Uses TCP and default ports for the given destination.
324 # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]
326 Uses TCP, default ports and IPv6.
329 # lttng create s1 -U net://myhost.com:3229
331 Create session s1 and set its consumer to myhost.com on port 3229 for control.
336 \fBdestroy\fP [NAME] [OPTIONS]
338 Teardown tracing session
340 Free memory on the session daemon and tracer side. It's gone!
342 If NAME is omitted, the session name is taken from the .lttngrc file.
348 Show summary of possible options and commands.
353 .BR "\-\-list-options"
354 Simple listing of options
359 \fBenable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
361 Enable tracing channel
363 To enable an event, you must enable both the event and the channel that
366 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
369 Exactly one of \-k or -u must be specified.
371 It is important to note that if a certain type of buffers is used, the session
372 will be set with that type and all other subsequent channel needs to have the
375 Note that once the session has been started and enabled on the tracer side,
376 it's not possible anymore to enable a new channel for that session.
384 .BR "\-\-list-options"
385 Simple listing of options
387 .BR "\-s, \-\-session NAME"
388 Apply on session name
390 .BR "\-k, \-\-kernel"
391 Apply to the kernel tracer
393 .BR "\-u, \-\-userspace"
394 Apply to the user-space tracer
397 Discard event when subbuffers are full (default)
400 Flight recorder mode: overwrites events when subbuffers are full. The
401 number of subbuffer must be 2 or more.
403 .BR "\-\-subbuf-size SIZE"
404 Subbuffer size in bytes {+k,+M,+G}.
405 (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
406 Rounded up to the next power of 2.
408 The minimum subbuffer size, for each tracer, is the max value between
409 the default above and the system page size. You can issue this command
410 to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
412 .BR "\-\-num-subbuf NUM"
413 Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4,
414 metadata: 2) Rounded up to the next power of 2.
416 .BR "\-\-switch-timer USEC"
417 Switch subbuffer timer interval in µsec.
418 (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
420 .BR "\-\-read-timer USEC"
421 Read timer interval in µsec.
422 (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
424 .BR "\-\-output TYPE"
425 Channel output type. Possible values: mmap, splice
426 (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
428 .BR "\-\-buffers-uid"
429 Use per UID buffer (\-u only). Buffers are shared between applications
430 that have the same UID.
432 .BR "\-\-buffers-pid"
433 Use per PID buffer (\-u only). Each application has its own buffers.
435 .BR "\-\-buffers-global"
436 Use shared buffer for the whole system (\-k only)
438 .BR "\-C, \-\-tracefile-size SIZE"
439 Maximum size of each tracefile within a stream (in bytes).
440 0 means unlimited. (default: 0)
442 .BR "\-W, \-\-tracefile-count COUNT"
443 Used in conjunction with \-C option, this will limit the number of files
444 created to the specified count. 0 means unlimited. (default: 0)
449 $ lttng enable-channel -k -C 4096 -W 32 chan1
451 For each stream, the maximum size of each trace file will be 4096 bytes and
452 there will be a maximum of 32 different files. The file count is appended after
453 the stream number as seen in the following example. The last trace file is
454 smaller than 4096 since it was not completely filled.
457 ~/lttng-traces/[...]/chan1_0_0 (4096)
458 ~/lttng-traces/[...]/chan1_0_1 (4096)
459 ~/lttng-traces/[...]/chan1_0_2 (3245)
460 ~/lttng-traces/[...]/chan1_1_0 (4096)
465 $ lttng enable-channel -k -C 4096
467 This will create trace files of 4096 bytes and will create new ones as long as
468 there is data available.
473 \fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]
477 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
478 omitted, a default channel named '\fBchannel0\fP' is created and the event is
479 added to it. If \fB\-c, \-\-channel\fP is omitted, but a non-default
480 channel already exists within the session, an error is returned. For the
481 user-space tracer, using \fB\-a, \-\-all\fP is the same as using the
484 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
491 Show summary of possible options and commands.
493 .BR "\-\-list-options"
494 Simple listing of options
496 .BR "\-s, \-\-session NAME"
497 Apply on session name
499 .BR "\-c, \-\-channel NAME"
500 Apply on channel name
503 Enable all tracepoints and syscalls. This actually enables a single
506 .BR "\-k, \-\-kernel"
507 Apply for the kernel tracer
509 .BR "\-u, \-\-userspace"
510 Apply for the user-space tracer
513 Apply for Java application using Java Util Logging interface (JUL)
516 Tracepoint event (default). Userspace tracer supports wildcards at the end
517 of string. Don't forget to quote to deal with bash expansion.
524 .BR "\-\-loglevel NAME"
525 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
526 For the JUL domain, the loglevel ranges are detailed with the \-\-help
527 option thus starting from SEVERE to FINEST.
529 .BR "\-\-loglevel-only NAME"
530 Tracepoint loglevel (only this loglevel).
531 The loglevel or loglevel-only options should be combined with a
532 tracepoint name or tracepoint wildcard.
534 .BR "\-\-probe (addr | symbol | symbol+offset)"
535 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
536 or hexadecimal (0xNNN...)
538 .BR "\-\-function (addr | symbol | symbol+offset)"
539 Dynamic function entry/return probe. Addr and offset can be octal
540 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
543 System call event. Enabling syscalls tracing (kernel tracer), you will
544 not be able to disable them with disable-event. This is a known
545 limitation. You can disable the entire channel to do the trick.
547 .BR "\-\-filter 'expression'"
548 Set a filter on a newly enabled event. Filter expression on event
549 fields and context. The event will be recorded if the filter's
550 expression evaluates to TRUE. Only specify on first activation of a
551 given event within a session.
552 Specifying a filter is only allowed when enabling events within a session before
553 tracing is started. If the filter fails to link with the event
554 within the traced domain, the event will be discarded.
555 Filtering is currently only implemented for the user-space tracer.
560 'intfield > 500 && intfield < 503'
561 '(strfield == "test" || intfield != 10) && intfield > 33'
562 'doublefield > 1.1 && intfield < 5.3'
565 Wildcards are allowed at the end of strings:
567 In string literals, the escape character is a '\\'. Use '\\*' for
568 the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
569 matches any sequence of characters, including an empty sub-string
570 (matches 0 or more characters).
572 Context information can be used for filtering. The examples below shows
573 usage of context filtering on the process name (using a wildcard), process ID
574 range, and unique thread ID. The process and thread IDs of
575 running applications can be found under columns "PID" and "LWP" of the
579 '$ctx.procname == "demo*"'
580 '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
584 Context information is available to all filters whether or not the add-context
585 command has been used to add it to the event's channel, as long as the context
586 field exists for that domain. For example, the filter examples given above will
587 never fail to link: no add-context is required for the event's channel.
590 .BR "\-x, \-\-exclude LIST"
591 Add exclusions to UST tracepoints:
592 Events that match any of the items in the comma-separated LIST are not
593 enabled, even if they match a wildcard definition of the event.
595 This option is also applicable with the \fB\-a, \-\-all\fP option,
596 in which case all UST tracepoints are enabled except the ones whose
597 names match any of the items in LIST.
602 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
604 Disable tracing channel
606 Disabling a channel disables the tracing of all of the channel's events. A channel
607 can be reenabled by calling \fBlttng enable-channel NAME\fP again.
609 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
616 Show summary of possible options and commands.
618 .BR "\-\-list-options"
619 Simple listing of options
621 .BR "\-s, \-\-session NAME"
622 Apply on session name
624 .BR "\-k, \-\-kernel"
625 Apply for the kernel tracer
627 .BR "\-u, \-\-userspace"
628 Apply for the user-space tracer
633 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
635 Disable tracing event
637 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
640 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
643 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
644 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
645 exists within the session, an error is returned.
651 Show summary of possible options and commands.
653 .BR "\-\-list-options"
654 Simple listing of options
656 .BR "\-s, \-\-session NAME"
657 Apply on session name
659 .BR "\-c, \-\-channel NAME"
660 Apply on channel name
662 .BR "\-a, \-\-all-events"
663 Disable all events. This does NOT disable "*" but rather every known
664 events of the session.
666 .BR "\-k, \-\-kernel"
667 Apply for the kernel tracer
669 .BR "\-u, \-\-userspace"
670 Apply for the user-space tracer
673 Apply for Java application using Java Util Logging interface (JUL)
678 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
680 List tracing session information.
682 With no arguments, it will list available tracing session(s).
684 With the session name, it will display the details of the session including
685 the trace file path, the associated channels and their state (activated
686 and deactivated), the activated events and more.
688 With \-k alone, it will list all available kernel events (except the system
690 With \-j alone, the available JUL event from registered application will be
691 list. The event corresponds to the Logger name in the Java JUL application.
692 With \-u alone, it will list all available user-space events from registered
693 applications. Here is an example of 'lttng list \-u':
696 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
697 ust_tests_hello:tptest_sighandler (type: tracepoint)
698 ust_tests_hello:tptest (type: tracepoint)
701 You can now enable any event listed by using the name :
702 \fBust_tests_hello:tptest\fP.
708 Show summary of possible options and commands.
710 .BR "\-\-list-options"
711 Simple listing of options
713 .BR "\-k, \-\-kernel"
716 .BR "\-u, \-\-userspace"
717 Select user-space domain.
720 Apply for Java application using JUL
722 .BR "\-f, \-\-fields"
729 .BR "\-c, \-\-channel NAME"
730 List details of a channel
732 .BR "\-d, \-\-domain"
733 List available domain(s)
738 \fBset-session\fP NAME [OPTIONS]
740 Set current session name
742 Will change the session name in the .lttngrc file.
748 Show summary of possible options and commands.
750 .BR "\-\-list-options"
751 Simple listing of options
756 \fBsnapshot\fP [OPTIONS] ACTION
758 Snapshot command for LTTng session.
764 Show summary of possible options and commands.
766 .BR "\-\-list-options"
767 Simple listing of options
773 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
775 Setup and add an snapshot output for a session. Output are the destination
776 where the snapshot will be sent. Only one output is permitted. To change it,
777 you'll need to delete it and add back the new one.
780 \fBdel-output\fP ID | NAME [-s <NAME>]
782 Delete an output for a session using the ID. You can either specify the
783 output's ID that can be found with list-output or the name.
786 \fBlist-output\fP [-s <NAME>]
788 List the output of a session. Attributes of the output are printed.
791 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
793 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
794 used instead of a previously added output. Specifying only a name or/and a max
795 size will override the current output values. For instance, you can record a
796 snapshot with a custom maximum size or with a different name.
799 $ lttng snapshot add-output -n mysnapshot file:///data/snapshot
801 $ lttng snapshot record -n new_name_snapshot
804 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
805 rather then in mysnapshot*/
808 .B DETAILED ACTION OPTIONS
811 .BR "\-s, \-\-session NAME"
812 Apply to session name.
814 .BR "\-n, \-\-name NAME"
815 Name of the snapshot's output.
817 .BR "\-m, \-\-max-size SIZE"
818 Maximum size in bytes of the snapshot. The maxium size does not include the
819 metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
822 .BR "\-C, \-\-ctrl-url URL"
823 Set control path URL. (Must use -D also)
825 .BR "\-D, \-\-data-url URL"
826 Set data path URL. (Must use -C also)
831 \fBstart\fP [NAME] [OPTIONS]
835 It will start tracing for all tracers for a specific tracing session.
836 If NAME is omitted, the session name is taken from the .lttngrc file.
842 Show summary of possible options and commands.
844 .BR "\-\-list-options"
845 Simple listing of options
850 \fBstop\fP [NAME] [OPTIONS]
854 It will stop tracing for all tracers for a specific tracing session. Before
855 returning, the command checks for data availability meaning that it will wait
856 until the trace is readable for the session. Use \-\-no-wait to avoid this
859 If NAME is omitted, the session name is taken from the .lttngrc file.
865 Show summary of possible options and commands.
867 .BR "\-\-list-options"
868 Simple listing of options
871 Don't wait for data availability.
878 Show version information
884 Show summary of possible options and commands.
886 .BR "\-\-list-options"
887 Simple listing of options
892 \fBview\fP [SESSION_NAME] [OPTIONS]
894 View traces of a tracing session. By default, the babeltrace viewer
895 will be used for text viewing. If SESSION_NAME is omitted, the session
896 name is taken from the .lttngrc file.
904 .BR "\-\-list-options"
905 Simple listing of options
907 .BR "\-t, \-\-trace-path PATH"
908 Trace directory path for the viewer
910 .BR "\-e, \-\-viewer CMD"
911 Specify viewer and/or options to use This will completely override the
912 default viewers so please make sure to specify the full command. The
913 trace directory path of the session will be appended at the end to the
919 This section explains the JUL domain (\-j, \-\-jul) where JUL stands for Java
920 Util Logging. You can use that feature by using the \fBliblttng-ust-jul.so\fP
921 from the lttng-ust(3) project.
923 The LTTng Java Agent uses JNI to link the UST tracer to the Java application
924 that uses the agent. Thus, it behaves similarly to the UST domain (\-u). When
925 enabling events with the JUL domain, you enable a Logger name that will then be
926 mapped to a default UST tracepoint called \fBlttng_jul:jul_event\fP in the
927 \fBlttng_jul_channel\fP. Using the lttng-ctl API, any JUL events must use the
928 tracepoint event type (same as \-\-tracepoint).
930 Because of the default immutable channel (\fBlttng_jul_channel\fP), the
931 \fBenable-channel\fP command CAN NOT be used with the JUL domain thus not
932 having any \-j option.
934 For JUL event, loglevels are supported with the JUL ABI values. Use \fBlttng
935 enable-event \-h\fP to list them. Wildcards are NOT supported except the "*"
936 meaning all events (same as \-a).
938 Exactly like the UST domain, if the Java application has the same UID as you,
939 you can trace it. Same goes for the tracing group accessing root applications.
941 Finally, you can list every Logger name that are available from JUL registered
942 applications to the session daemon by using \fBlttng list \-j\fP.
944 Here is an example on how to use this domain.
949 $ lttng create aSession
950 $ lttng enable-event -s aSession -j MyCustomLoggerName
954 More information can be found in the lttng-ust documentation, see
955 java-util-logging.txt
960 On success 0 is returned and a positive value on error. Value of 1 means a command
961 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
962 something went wrong during the command.
964 Any other value above 10, please refer to
965 .BR "<lttng/lttng-error.h>"
966 for a detailed list or use lttng_strerror() to get a human readable string of
970 .SH "ENVIRONMENT VARIABLES"
973 Note that all command line options override environment variables.
977 .IP "LTTNG_SESSIOND_PATH"
978 Allows one to specify the full session daemon binary path to lttng command line
979 tool. You can also use \-\-sessiond-path option having the same effect.
985 .BR lttng-sessiond(8),
991 If you encounter any issues or usability problem, please report it on our
992 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
993 at https://bugs.lttng.org which is a bugtracker.
999 lttng is distributed under the GNU General Public License version 2. See the file
1000 COPYING for details.
1002 A Web site is available at http://lttng.org for more information on the LTTng
1005 You can also find our git tree at http://git.lttng.org.
1007 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
1009 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
1014 Thanks to Yannick Brosseau without whom this project would never have been so
1015 lean and mean! Also thanks to the Ericsson teams working on tracing which
1016 helped us greatly with detailed bug reports and unusual test cases.
1018 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
1019 maintainer) and Jon Bernard for our Debian packages.
1021 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
1022 Montreal for the LTTng journey.
1027 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
1028 David Goulet. More people have since contributed to it. It is currently
1029 maintained by Jérémie Galarneau <jeremie.galarneau@efficios.com>.