Man page: reference lttng-crash under --shm-path option
[lttng-tools.git] / doc / man / lttng.1
1 .TH "LTTNG" "1" "May 13th, 2014" "" ""
2
3 .SH "NAME"
4 lttng \- LTTng 2.x tracer control command line tool
5
6 .SH "SYNOPSIS"
7
8 .PP
9 lttng [OPTIONS] <COMMAND>
10 .SH "DESCRIPTION"
11
12 .PP
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.
17
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
21 package.
22
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.
28
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
34 kernel event.
35
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.
43
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).
48 .SH "OPTIONS"
49
50 .PP
51 This program follows the usual GNU command line syntax with long options starting with
52 two dashes. Below is a summary of the available options.
53 .PP
54
55 .TP
56 .BR "\-h, \-\-help"
57 Show summary of possible options and commands.
58 .TP
59 .BR "\-V, \-\-version"
60 Show version.
61 .TP
62 .BR "\-v, \-\-verbose"
63 Increase verbosity.
64 Three levels of verbosity are available which are triggered by putting additional v to
65 the option (\-vv or \-vvv)
66 .TP
67 .BR "\-q, \-\-quiet"
68 Suppress all messages (even errors).
69 .TP
70 .BR "\-g, \-\-group NAME"
71 Set unix tracing group name. (default: tracing)
72 .TP
73 .BR "\-n, \-\-no-sessiond"
74 Don't automatically spawn a session daemon.
75 .TP
76 .BR "\-\-sessiond\-path PATH"
77 Set session daemon full binary path.
78 .TP
79 .BR "\-\-list\-options"
80 Simple listing of lttng options.
81 .TP
82 .BR "\-\-list\-commands"
83 Simple listing of lttng commands.
84 .TP
85 .BR "\-m, \-\-mi TYPE
86 Machine interface
87
88 TYPE supported: XML
89
90 Machine interface (MI) mode converts the traditional pretty printing to a
91 machine output syntax. MI mode provides a format change-resistant way to access
92 information generated via the lttng command line.
93
94 When using MI mode, the data is printed on \fBstdout\fP. Error and warning are
95 printed on \fBstderr\fP with the pretty print default format.
96
97 If any errors occur during the execution of a command, the return value of the
98 command will be different than zero. In this case, lttng does NOT guarantee the
99 syntax and data validity of the generated MI output.
100
101 For XML output type, a schema definition (XSD) file used for validation can be
102 found under src/common/mi_lttng.xsd
103
104 .SH "COMMANDS"
105
106 .PP
107 \fBadd-context\fP [OPTIONS]
108 .RS
109 Add context to event(s) and/or channel(s).
110
111 A context is basically extra information appended to a channel. For instance,
112 you could ask the tracer to add the PID information for all events in a
113 channel. You can also add performance monitoring unit counters (perf PMU) using
114 the perf kernel API.
115
116 For example, this command will add the context information 'prio' and two per-CPU
117 perf counters (hardware branch misses and cache misses), to all events in the trace
118 data output:
119
120 .nf
121 # lttng add-context \-k \-t prio \-t perf:cpu:branch-misses \\
122 \-t perf:cpu:cache-misses
123 .fi
124
125 Please take a look at the help (\-h/\-\-help) for a detailed list of available
126 contexts.
127
128 Perf counters are available as per-CPU ("perf:cpu:...") and per-thread
129 ("perf:thread:...") counters. Currently, per-CPU counters can only be
130 used with the kernel tracing domain, and per-thread counters can only be
131 used with the UST tracing domain.
132
133 If no channel is given (\-c), the context is added to all channels that were
134 already enabled. If the session has no channel, a default channel is created.
135 Otherwise the context will be added only to the given channel (\-c).
136
137 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
138 file.
139
140 .B OPTIONS:
141
142 .TP
143 .BR "\-h, \-\-help"
144 Show summary of possible options and commands.
145 .TP
146 .BR "\-s, \-\-session NAME"
147 Apply on session name.
148 .TP
149 .BR "\-c, \-\-channel NAME"
150 Apply on channel name.
151 .TP
152 .BR "\-k, \-\-kernel"
153 Apply for the kernel tracer
154 .TP
155 .BR "\-u, \-\-userspace"
156 Apply for the user-space tracer
157 .TP
158 .BR "\-t, \-\-type TYPE"
159 Context type. You can repeat this option on the command line. Please
160 use "lttng add-context \-h" to list all available types.
161 .RE
162 .PP
163
164 .PP
165 \fBcalibrate\fP [OPTIONS]
166 .RS
167 Quantify LTTng overhead
168
169 The LTTng calibrate command can be used to find out the combined average
170 overhead of the LTTng tracer and the instrumentation mechanisms used. This
171 overhead can be calibrated in terms of time or using any of the PMU performance
172 counter available on the system.
173
174 For now, the only calibration implemented is that of the kernel function
175 instrumentation (kretprobes).
176
177 * Calibrate kernel function instrumentation
178
179 Let's use an example to show this calibration. We use an i7 processor with 4
180 general-purpose PMU registers. This information is available by issuing dmesg,
181 looking for "generic registers".
182
183 This sequence of commands will gather a trace executing a kretprobe hooked on
184 an empty function, gathering PMU counters LLC (Last Level Cache) misses
185 information (see lttng add-context \-\-help to see the list of available PMU
186 counters).
187
188 .nf
189 # lttng create calibrate-function
190 # lttng enable-event calibrate \-\-kernel \\
191 \-\-function lttng_calibrate_kretprobe
192 # lttng add-context \-\-kernel \-t perf:cpu:LLC-load-misses \\
193 \-t perf:cpu:LLC-store-misses \\
194 \-t perf:cpu:LLC-prefetch-misses
195 # lttng start
196 # for a in $(seq 1 10); do \\
197 lttng calibrate \-\-kernel \-\-function;
198 done
199 # lttng destroy
200 # babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
201 | tail \-n 1)
202 .fi
203
204 The output from babeltrace can be saved to a text file and opened in a
205 spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
206 consecutive "calibrate_entry" and "calibrate_return" events. Note that these
207 counters are per-CPU, so scheduling events would need to be present to account
208 for migration between CPU. Therefore, for calibration purposes, only events
209 staying on the same CPU must be considered.
210
211 The average result, for the i7, on 10 samples:
212
213 .nf
214 Average Std.Dev.
215 perf_LLC_load_misses: 5.0 0.577
216 perf_LLC_store_misses: 1.6 0.516
217 perf_LLC_prefetch_misses: 9.0 14.742
218 .fi
219
220 As we can notice, the load and store misses are relatively stable across runs
221 (their standard deviation is relatively low) compared to the prefetch misses.
222 We can conclude from this information that LLC load and store misses can be
223 accounted for quite precisely, but prefetches within a function seems to behave
224 too erratically (not much causality link between the code executed and the CPU
225 prefetch activity) to be accounted for.
226
227 .B OPTIONS:
228
229 .TP
230 .BR "\-h, \-\-help"
231 Show summary of possible options and commands.
232 .TP
233 .BR "\-k, \-\-kernel"
234 Apply for the kernel tracer
235 .TP
236 .BR "\-u, \-\-userspace"
237 Apply for the user-space tracer
238 .TP
239 .BR "\-\-function"
240 Dynamic function entry/return probe (default)
241 .RE
242 .PP
243
244 .PP
245 \fBcreate\fP [NAME] [OPTIONS]
246 .RS
247 Create tracing session.
248
249 A tracing session contains channel(s) which contains event(s). It is domain
250 agnostic, meaning that channels and events can be enabled for the
251 user-space tracer and/or the kernel tracer. It acts like a container
252 aggregating multiple tracing sources.
253
254 On creation, a \fB.lttngrc\fP file is created in your $HOME directory
255 containing the current session name. If NAME is omitted, a session name is
256 automatically created having this form: 'auto-yyyymmdd-hhmmss'.
257
258 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
259 $HOME/lttng-traces.
260
261 The $HOME environment variable can be overridden by defining the environment
262 variable LTTNG_HOME. This is useful when the user running the commands has
263 a non-writeable home directory.
264
265 The session name MUST NOT contain the character '/'.
266
267 .B OPTIONS:
268
269 .TP
270 .BR "\-h, \-\-help"
271 Show summary of possible options and commands.
272 .TP
273 .BR "\-\-list-options"
274 Simple listing of options
275 .TP
276 .BR "\-o, \-\-output PATH"
277 Specify output path for traces
278 .TP
279 .BR "\-\-no-output"
280 Traces will not be output
281 .TP
282 .BR "\-\-snapshot"
283 Set the session in snapshot mode. Created in no-output mode and uses the
284 URL, if one is specified, as the default snapshot output. Every channel will be set
285 in overwrite mode and with mmap output (splice not supported).
286 .TP
287 .BR "\-\-live [USEC]"
288 Set the session exclusively in live mode. The parameter is the delay in micro
289 seconds before the data is flushed and streamed. The live mode allows you to
290 stream the trace and view it while it's being recorded by any tracer. For that,
291 you need a lttng-relayd and this session requires a network URL (\-U or
292 \-C/\-D). If no USEC nor URL is provided, the default is to use a timer value
293 set to 1000000 and the network URL set to net://127.0.0.1.
294
295 To read a live session, you can use babeltrace(1) or the live streaming
296 protocol in doc/live-reading-protocol.txt. Here is an example:
297
298 .nf
299 $ lttng-relayd -o /tmp/lttng
300 $ lttng create --live 200000 -U net://localhost
301 $ lttng enable-event -a --userspace
302 $ lttng start
303 .fi
304
305 After the start, you'll be able to read the events while they are being
306 recorded in /tmp/lttng.
307
308 .TP
309 .BR "\-\-shm-path PATH"
310
311 Path where shared memory holding buffers should be created. Useful
312 when used with PRAMFS or other persistent memory filesystems to extract
313 trace data in the event of a crash requiring a reboot.
314
315 See the \fBlttng-crash(1)\fP utility for more information on crash recovery.
316
317 .TP
318 .BR "\-U, \-\-set-url=URL"
319 Set URL for the consumer output destination. It is persistent for the
320 session lifetime. Redo the command to change it. This will set both data
321 and control URL for network.
322 .TP
323 .BR "\-C, \-\-ctrl-url=URL"
324 Set control path URL. (Must use -D also)
325 .TP
326 .BR "\-D, \-\-data-url=URL"
327 Set data path URL. (Must use -C also)
328 .PP
329 Using these options, each API call can be controlled individually. For
330 instance, \-C does not enable the consumer automatically. You'll need the \-e
331 option for that.
332
333 .B URL FORMAT:
334
335 proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]
336
337 Supported protocols are (proto):
338 .TP
339 .BR "file://..."
340 Local filesystem full path.
341
342 .TP
343 .BR "net://..."
344 This will use the default network transport layer which is TCP for both
345 control (PORT1) and data port (PORT2). The default ports are
346 respectively 5342 and 5343. Note that net[6]:// is not yet supported.
347
348 .TP
349 .BR "tcp[6]://..."
350 Can only be used with -C and -D together
351
352 NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)
353
354 .B EXAMPLES:
355
356 .nf
357 # lttng create -U net://192.168.1.42
358 .fi
359 Uses TCP and default ports for the given destination.
360
361 .nf
362 # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]
363 .fi
364 Uses TCP, default ports and IPv6.
365
366 .nf
367 # lttng create s1 -U net://myhost.com:3229
368 .fi
369 Create session s1 and set its consumer to myhost.com on port 3229 for control.
370 .RE
371 .PP
372
373 .PP
374 \fBdestroy\fP [NAME] [OPTIONS]
375 .RS
376 Teardown tracing session
377
378 Free memory on the session daemon and tracer side. It's gone!
379
380 If NAME is omitted, the session name is taken from the .lttngrc file.
381
382 .B OPTIONS:
383
384 .TP
385 .BR "\-h, \-\-help"
386 Show summary of possible options and commands.
387 .TP
388 .BR "\-a, \-\-all"
389 Destroy all sessions
390 .TP
391 .BR "\-\-list-options"
392 Simple listing of options
393 .RE
394 .PP
395
396 .PP
397 \fBenable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
398 .RS
399 Enable tracing channel
400
401 To enable an event, you must enable both the event and the channel that
402 contains it.
403
404 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
405 file.
406
407 Exactly one of \-k or -u must be specified.
408
409 It is important to note that if a certain type of buffers is used, the session
410 will be set with that type and all other subsequent channel needs to have the
411 same type.
412
413 Note that once the session has been started and enabled on the tracer side,
414 it's not possible anymore to enable a new channel for that session.
415
416 .B OPTIONS:
417
418 .TP
419 .BR "\-h, \-\-help"
420 Show this help
421 .TP
422 .BR "\-\-list-options"
423 Simple listing of options
424 .TP
425 .BR "\-s, \-\-session NAME"
426 Apply on session name
427 .TP
428 .BR "\-k, \-\-kernel"
429 Apply to the kernel tracer
430 .TP
431 .BR "\-u, \-\-userspace"
432 Apply to the user-space tracer
433 .TP
434 .BR "\-\-discard"
435 Discard event when subbuffers are full (default)
436 .TP
437 .BR "\-\-overwrite"
438 Flight recorder mode: overwrites events when subbuffers are full. The
439 number of subbuffer must be 2 or more.
440 .TP
441 .BR "\-\-subbuf-size SIZE"
442 Subbuffer size in bytes {+k,+M,+G}.
443 (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
444 Rounded up to the next power of 2.
445
446 The minimum subbuffer size, for each tracer, is the max value between
447 the default above and the system page size. You can issue this command
448 to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
449 .TP
450 .BR "\-\-num-subbuf NUM"
451 Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4,
452 metadata: 2) Rounded up to the next power of 2.
453 .TP
454 .BR "\-\-switch-timer USEC"
455 Switch subbuffer timer interval in µsec.
456 (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
457 .TP
458 .BR "\-\-read-timer USEC"
459 Read timer interval in µsec.
460 (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
461 .TP
462 .BR "\-\-output TYPE"
463 Channel output type. Possible values: mmap, splice
464 (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
465 .TP
466 .BR "\-\-buffers-uid"
467 Use per UID buffer (\-u only). Buffers are shared between applications
468 that have the same UID.
469 .TP
470 .BR "\-\-buffers-pid"
471 Use per PID buffer (\-u only). Each application has its own buffers.
472 .TP
473 .BR "\-\-buffers-global"
474 Use shared buffer for the whole system (\-k only)
475 .TP
476 .BR "\-C, \-\-tracefile-size SIZE"
477 Maximum size of each tracefile within a stream (in bytes).
478 0 means unlimited. (default: 0)
479 Note: traces generated with this option may inaccurately report
480 discarded events as of CTF 1.8.
481 .TP
482 .BR "\-W, \-\-tracefile-count COUNT"
483 Used in conjunction with \-C option, this will limit the number of files
484 created to the specified count. 0 means unlimited. (default: 0)
485
486 .B EXAMPLES:
487
488 .nf
489 $ lttng enable-channel -k -C 4096 -W 32 chan1
490 .fi
491 For each stream, the maximum size of each trace file will be 4096 bytes and
492 there will be a maximum of 32 different files. The file count is appended after
493 the stream number as seen in the following example. The last trace file is
494 smaller than 4096 since it was not completely filled.
495
496 .nf
497 ~/lttng-traces/[...]/chan1_0_0 (4096)
498 ~/lttng-traces/[...]/chan1_0_1 (4096)
499 ~/lttng-traces/[...]/chan1_0_2 (3245)
500 ~/lttng-traces/[...]/chan1_1_0 (4096)
501 ...
502 .fi
503
504 .nf
505 $ lttng enable-channel -k -C 4096
506 .fi
507 This will create trace files of 4096 bytes and will create new ones as long as
508 there is data available.
509 .RE
510 .PP
511
512 .PP
513 \fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]
514 .RS
515 Enable tracing event
516
517 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
518 omitted, a default channel named '\fBchannel0\fP' is created and the event is
519 added to it. If \fB\-c, \-\-channel\fP is omitted, but a non-default
520 channel already exists within the session, an error is returned. For the
521 user-space tracer, using \fB\-a, \-\-all\fP is the same as using the
522 wildcard "*".
523
524 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
525 file.
526
527 .B OPTIONS:
528
529 .TP
530 .BR "\-h, \-\-help"
531 Show summary of possible options and commands.
532 .TP
533 .BR "\-\-list-options"
534 Simple listing of options
535 .TP
536 .BR "\-s, \-\-session NAME"
537 Apply on session name
538 .TP
539 .BR "\-c, \-\-channel NAME"
540 Apply on channel name
541 .TP
542 .BR "\-a, \-\-all"
543 Enable all tracepoints and syscalls. This actually enables a single
544 wildcard event "*".
545 .TP
546 .BR "\-k, \-\-kernel"
547 Apply for the kernel tracer
548 .TP
549 .BR "\-u, \-\-userspace"
550 Apply for the user-space tracer
551 .TP
552 .BR "\-j, \-\-jul"
553 Apply for Java application using Java Util Logging interface (JUL)
554 .TP
555 .BR "\-l, \-\-log4j"
556 Apply for Java application using LOG4J
557 .TP
558 .BR "\-p, \-\-python"
559 Apply for Python application using the logging module.
560 .TP
561 .BR "\-\-tracepoint"
562 Tracepoint event (default). Userspace tracer supports wildcards at the end
563 of string. Don't forget to quote to deal with bash expansion.
564 e.g.:
565 .nf
566 "*"
567 "app_component:na*"
568 .fi
569 .TP
570 .BR "\-\-loglevel NAME"
571 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
572 For the JUL domain, the loglevel ranges are detailed with the \-\-help
573 option thus starting from SEVERE to FINEST.
574 For the LOG4J domain, loglevels range from FATAL to TRACE which are also
575 detailed in the help.
576 For the Python domain, loglevels range from CRITICAL to DEBUG which are
577 detailed in the help as well.
578 .TP
579 .BR "\-\-loglevel-only NAME"
580 Tracepoint loglevel (only this loglevel).
581 The loglevel or loglevel-only options should be combined with a
582 tracepoint name or tracepoint wildcard.
583 .TP
584 .BR "\-\-probe (addr | symbol | symbol+offset)"
585 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
586 or hexadecimal (0xNNN...)
587 .TP
588 .BR "\-\-function (addr | symbol | symbol+offset)"
589 Dynamic function entry/return probe. Addr and offset can be octal
590 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
591 .TP
592 .BR "\-\-syscall"
593 System call event. Enabling syscalls tracing (kernel tracer), you will
594 not be able to disable them with disable-event. This is a known
595 limitation. You can disable the entire channel to do the trick. Also note
596 that per-syscall selection is not supported yet. Use with "-a" to enable
597 all syscalls.
598 .TP
599 .BR "\-\-filter 'expression'"
600 Set a filter on a newly enabled event. Filter expression on event
601 fields and context. The event will be recorded if the filter's
602 expression evaluates to TRUE. Only specify on first activation of a
603 given event within a session.
604 Specifying a filter is only allowed when enabling events within a session before
605 tracing is started. If the filter fails to link with the event
606 within the traced domain, the event will be discarded.
607 Filtering is currently only implemented for the user-space tracer.
608
609 Expression examples:
610
611 .nf
612 'intfield > 500 && intfield < 503'
613 '(strfield == "test" || intfield != 10) && intfield > 33'
614 'doublefield > 1.1 && intfield < 5.3'
615 .fi
616
617 Wildcards are allowed at the end of strings:
618 'seqfield1 == "te*"'
619 In string literals, the escape character is a '\\'. Use '\\*' for
620 the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
621 matches any sequence of characters, including an empty sub-string
622 (matches 0 or more characters).
623
624 Context information can be used for filtering. The examples below shows
625 usage of context filtering on the process name (using a wildcard), process ID
626 range, and unique thread ID. The process and thread IDs of
627 running applications can be found under columns "PID" and "LWP" of the
628 "ps -eLf" command.
629
630 .nf
631 '$ctx.procname == "demo*"'
632 '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
633 '$ctx.vtid == 1234'
634 .fi
635
636 Context information is available to all filters whether or not the add-context
637 command has been used to add it to the event's channel, as long as the context
638 field exists for that domain. For example, the filter examples given above will
639 never fail to link: no add-context is required for the event's channel.
640
641 .TP
642 .BR "\-x, \-\-exclude LIST"
643 Add exclusions to UST tracepoints:
644 Events that match any of the items in the comma-separated LIST are not
645 enabled, even if they match a wildcard definition of the event.
646
647 This option is also applicable with the \fB\-a, \-\-all\fP option,
648 in which case all UST tracepoints are enabled except the ones whose
649 names match any of the items in LIST.
650 .RE
651 .PP
652
653 .PP
654 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
655 .RS
656 Disable tracing channel
657
658 Disabling a channel disables the tracing of all of the channel's events. A channel
659 can be re-enabled by calling \fBlttng enable-channel NAME\fP again.
660
661 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
662 file.
663
664 .B OPTIONS:
665
666 .TP
667 .BR "\-h, \-\-help"
668 Show summary of possible options and commands.
669 .TP
670 .BR "\-\-list-options"
671 Simple listing of options
672 .TP
673 .BR "\-s, \-\-session NAME"
674 Apply on session name
675 .TP
676 .BR "\-k, \-\-kernel"
677 Apply for the kernel tracer
678 .TP
679 .BR "\-u, \-\-userspace"
680 Apply for the user-space tracer
681 .RE
682 .PP
683
684 .PP
685 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
686 .RS
687 Disable tracing event
688
689 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
690 NAME\fP again.
691
692 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
693 file.
694
695 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
696 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
697 exists within the session, an error is returned.
698
699 .B OPTIONS:
700
701 .TP
702 .BR "\-h, \-\-help"
703 Show summary of possible options and commands.
704 .TP
705 .BR "\-\-list-options"
706 Simple listing of options
707 .TP
708 .BR "\-s, \-\-session NAME"
709 Apply on session name
710 .TP
711 .BR "\-c, \-\-channel NAME"
712 Apply on channel name
713 .TP
714 .BR "\-a, \-\-all-events"
715 Disable all events. This does NOT disable "*" but rather every known
716 events of the session.
717 .TP
718 .BR "\-k, \-\-kernel"
719 Apply for the kernel tracer
720 .TP
721 .BR "\-u, \-\-userspace"
722 Apply for the user-space tracer
723 .TP
724 .BR "\-j, \-\-jul"
725 Apply for Java application using Java Util Logging interface (JUL)
726 .TP
727 .BR "\-l, \-\-log4j"
728 Apply for Java application using LOG4J
729 .TP
730 .BR "\-p, \-\-python"
731 Apply for Python application using the logging module.
732 .RE
733 .PP
734
735 .PP
736 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
737 .RS
738 List tracing session information.
739
740 With no arguments, it will list available tracing session(s).
741
742 With the session name, it will display the details of the session including
743 the trace file path, the associated channels and their state (activated
744 and deactivated), the activated events and more.
745
746 With \-k alone, it will list all available kernel events (except the system
747 calls events).
748 With \-j alone, the available JUL event from registered application will be
749 list. The event corresponds to the Logger name in the Java JUL application.
750 With \-l alone, the available LOG4J event from registered application will be
751 list. The event corresponds to the Logger name in the Java LOG4J application.
752 With \-p alone, the available Python event from registered application will be
753 list. The event corresponds to the Logger name in the Python application.
754 With \-u alone, it will list all available user-space events from registered
755 applications. Here is an example of 'lttng list \-u':
756
757 .nf
758 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
759 ust_tests_hello:tptest_sighandler (type: tracepoint)
760 ust_tests_hello:tptest (type: tracepoint)
761 .fi
762
763 You can now enable any event listed by using the name :
764 \fBust_tests_hello:tptest\fP.
765
766 .B OPTIONS:
767
768 .TP
769 .BR "\-h, \-\-help"
770 Show summary of possible options and commands.
771 .TP
772 .BR "\-\-list-options"
773 Simple listing of options
774 .TP
775 .BR "\-k, \-\-kernel"
776 Select kernel domain
777 .TP
778 .BR "\-u, \-\-userspace"
779 Select user-space domain.
780 .TP
781 .BR "\-j, \-\-jul"
782 Apply for Java application using JUL
783 .TP
784 .BR "\-l, \-\-log4j"
785 Apply for Java application using LOG4J
786 .TP
787 .BR "\-p, \-\-python"
788 Apply for Python application using the logging module.
789 .TP
790 .BR "\-f, \-\-fields"
791 List event fields
792
793 .PP
794 .B SESSION OPTIONS:
795
796 .TP
797 .BR "\-c, \-\-channel NAME"
798 List details of a channel
799 .TP
800 .BR "\-d, \-\-domain"
801 List available domain(s)
802 .RE
803 .PP
804
805 .PP
806 \fBload\fP [OPTIONS] [NAME]
807 .RS
808 Load tracing session configuration
809
810 If NAME is omitted, all session configurations found in both the user's session
811 configuration directory (default: ~/.lttng/sessions/) and the system session
812 configuration directory (default: /etc/lttng/sessions/) will be loaded. Note
813 that the sessions in the user directory are loaded first and then the system
814 wide directory are loaded.
815
816 .B OPTIONS:
817
818 .TP
819 .BR "\-h, \-\-help"
820 Show summary of possible options and commands.
821 .TP
822 .BR "\-a, \-\-all"
823 Load all session configurations (default).
824 .TP
825 .BR "\-i, \-\-input-path PATH"
826 Specify the input path for session configurations. This overrides the default
827 session configuration directory.
828 .TP
829 .BR "\-f, -\-force"
830 Overwrite current session configuration(s) if a session of the same name
831 already exists.
832 .RE
833 .PP
834
835 .PP
836 \fBsave\fP [OPTIONS] [SESSION]
837 .RS
838 Save tracing session configuration
839
840 If SESSION is omitted, all session configurations will be saved to individual
841 \fB.lttng\fP files under the user's session configuration directory (default:
842 ~/.lttng/sessions/). The default session configuration file naming scheme is
843 \fBSESSION.lttng\fP.
844
845 For instance, a user in the tracing group saving a session from a root session
846 daemon will save it in her/his user directory.
847
848 .B OPTIONS:
849
850 .TP
851 .BR "\-h, \-\-help"
852 Show summary of possible options and commands.
853 .TP
854 .BR "\-a, \-\-all"
855 Save all session configurations (default).
856 .TP
857 .BR "\-o, \-\-output-path PATH"
858 Specify the output path for saved sessions. This overrides the default session
859 configuration directory.
860 .TP
861 .BR "\-f, -\-force"
862 Overwrite session configuration file if session name clashes.
863 .RE
864 .PP
865
866 .PP
867 \fBset-session\fP NAME [OPTIONS]
868 .RS
869 Set current session name
870
871 Will change the session name in the .lttngrc file.
872
873 .B OPTIONS:
874
875 .TP
876 .BR "\-h, \-\-help"
877 Show summary of possible options and commands.
878 .TP
879 .BR "\-\-list-options"
880 Simple listing of options
881 .RE
882 .PP
883
884 .PP
885 \fBsnapshot\fP [OPTIONS] ACTION
886 .RS
887 Snapshot command for LTTng session.
888
889 .B OPTIONS:
890
891 .TP
892 .BR "\-h, \-\-help"
893 Show summary of possible options and commands.
894 .TP
895 .BR "\-\-list-options"
896 Simple listing of options
897
898 .PP
899 .B ACTION:
900
901 .TP
902 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
903
904 Setup and add a snapshot output for a session. Output is the destination
905 where the snapshot will be sent. Only one output is permitted. To change it,
906 you'll need to delete it and add back the new one.
907
908 .TP
909 \fBdel-output\fP ID | NAME [-s <NAME>]
910
911 Delete an output for a session using the output's ID. You can either specify the
912 output by name or use its ID as returned by the list-output command.
913
914 .TP
915 \fBlist-output\fP [-s <NAME>]
916
917 List the output of a session. Attributes of the output are printed.
918
919 .TP
920 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
921
922 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
923 used instead of a previously added output. Specifying only a name or/and a max
924 size will override the current output values. For instance, you can record a
925 snapshot with a custom maximum size or with a different name.
926
927 .nf
928 $ lttng snapshot add-output -n mysnapshot file:///data/snapshot
929 [...]
930 $ lttng snapshot record -n new_name_snapshot
931 .fi
932
933 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
934 rather then in mysnapshot*/
935
936 .PP
937 .B DETAILED ACTION OPTIONS
938
939 .TP
940 .BR "\-s, \-\-session NAME"
941 Apply to session name.
942 .TP
943 .BR "\-n, \-\-name NAME"
944 Name of the snapshot's output.
945 .TP
946 .BR "\-m, \-\-max-size SIZE"
947 Maximum size in bytes of the snapshot. The maximum size does not include the
948 metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
949 \-\-max-size 5M
950 .TP
951 .BR "\-C, \-\-ctrl-url URL"
952 Set control path URL. (Must use -D also)
953 .TP
954 .BR "\-D, \-\-data-url URL"
955 Set data path URL. (Must use -C also)
956 .RE
957 .PP
958
959 .PP
960 \fBstart\fP [NAME] [OPTIONS]
961 .RS
962 Start tracing
963
964 It will start tracing for all tracers for a specific tracing session.
965 If NAME is omitted, the session name is taken from the .lttngrc file.
966
967 .B OPTIONS:
968
969 .TP
970 .BR "\-h, \-\-help"
971 Show summary of possible options and commands.
972 .TP
973 .BR "\-\-list-options"
974 Simple listing of options
975 .RE
976 .PP
977
978 .PP
979 \fBstop\fP [NAME] [OPTIONS]
980 .RS
981 Stop tracing
982
983 It will stop tracing for all tracers for a specific tracing session. Before
984 returning, the command checks for data availability meaning that it will wait
985 until the trace is readable for the session. Use \-\-no-wait to avoid this
986 behavior.
987
988 If NAME is omitted, the session name is taken from the .lttngrc file.
989
990 .B OPTIONS:
991
992 .TP
993 .BR "\-h, \-\-help"
994 Show summary of possible options and commands.
995 .TP
996 .BR "\-\-list-options"
997 Simple listing of options
998 .TP
999 .BR "\-\-no-wait"
1000 Don't wait for data availability.
1001 .RE
1002 .PP
1003
1004 .PP
1005 \fBversion\fP
1006 .RS
1007 Show version information
1008
1009 .B OPTIONS:
1010
1011 .TP
1012 .BR "\-h, \-\-help"
1013 Show summary of possible options and commands.
1014 .TP
1015 .BR "\-\-list-options"
1016 Simple listing of options
1017 .RE
1018 .PP
1019
1020 .PP
1021 \fBview\fP [SESSION_NAME] [OPTIONS]
1022 .RS
1023 View traces of a tracing session. By default, the babeltrace viewer
1024 will be used for text viewing. If SESSION_NAME is omitted, the session
1025 name is taken from the .lttngrc file.
1026
1027 .B OPTIONS:
1028
1029 .TP
1030 .BR "\-h, \-\-help"
1031 Show this help
1032 .TP
1033 .BR "\-\-list-options"
1034 Simple listing of options
1035 .TP
1036 .BR "\-t, \-\-trace-path PATH"
1037 Trace directory path for the viewer
1038 .TP
1039 .BR "\-e, \-\-viewer CMD"
1040 Specify viewer and/or options to use This will completely override the
1041 default viewers so please make sure to specify the full command. The
1042 trace directory path of the session will be appended at the end to the
1043 arguments
1044 .RE
1045 .PP
1046
1047 .SH "JUL/LOG4J DOMAIN"
1048
1049 This section explains the JUL and LOG4J domain where JUL stands for Java Util
1050 Logging. You can use these by using the \fBliblttng-ust-<domain>-jni.so\fP from
1051 the lttng-ust(3) project.
1052
1053 The LTTng Java Agent uses JNI to link the UST tracer to the Java application
1054 that uses the agent. Thus, it behaves similarly to the UST domain (\-u). When
1055 enabling events, you enable a Logger name that will then be mapped to a default
1056 UST tracepoint called \fBlttng_jul:<domain>_event\fP in the
1057 \fBlttng_<domain>_channel\fP. Using the lttng-ctl API, any JUL/LOG4J events
1058 must use the tracepoint event type (same as \-\-tracepoint).
1059
1060 Because of the default immutable channel, the \fBenable-channel\fP command CAN
1061 NOT be used with the JUL and LOG4J domain thus not having any options.
1062
1063 Also, loglevels are supported. Use \fBlttng enable-event \-h\fP to list them.
1064 Wildcards are NOT supported except the "*" meaning all events (same as \-a).
1065
1066 Exactly like the UST domain, if the Java application has the same UID as you,
1067 you can trace it. Same goes for the tracing group accessing root applications.
1068
1069 Finally, you can list every Logger name that are available from registered
1070 applications to the session daemon by using \fBlttng list \-j\fP or \fB\-l\fP.
1071
1072 Here is an example on how to use the JUL domain.
1073
1074 .nf
1075 $ lttng list -j
1076 [...]
1077 $ lttng create aSession
1078 $ lttng enable-event -s aSession -j MyCustomLoggerName
1079 $ lttng start
1080 .fi
1081
1082 More information can be found in the lttng-ust documentation, see
1083 java-util-logging.txt
1084 .PP
1085
1086 .SH "EXIT VALUES"
1087 .PP
1088 On success 0 is returned and a positive value on error. Value of 1 means a command
1089 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
1090 something went wrong during the command.
1091
1092 Any other value above 10, please refer to
1093 .BR "<lttng/lttng-error.h>"
1094 for a detailed list or use lttng_strerror() to get a human readable string of
1095 the error code.
1096 .PP
1097
1098 .SH "ENVIRONMENT VARIABLES"
1099
1100 .PP
1101 Note that all command line options override environment variables.
1102 .PP
1103
1104 .PP
1105 .IP "LTTNG_SESSIOND_PATH"
1106 Allows one to specify the full session daemon binary path to lttng command line
1107 tool. You can also use \-\-sessiond-path option having the same effect.
1108 .PP
1109
1110 .PP
1111 .IP "LTTNG_SESSION_CONFIG_XSD_PATH"
1112 Set the path in which the \fBsession.xsd\fP session configuration schema may be
1113 found.
1114 .PP
1115
1116 .SH "SEE ALSO"
1117 .BR babeltrace(1),
1118 .BR lttng-ust(3),
1119 .BR lttng-sessiond(8),
1120 .BR lttng-relayd(8),
1121 .BR lttng-crash(1),
1122
1123 .SH "BUGS"
1124
1125 .PP
1126 If you encounter any issues or usability problem, please report it on our
1127 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
1128 at https://bugs.lttng.org which is a bug tracker.
1129 .PP
1130
1131 .SH "CREDITS"
1132
1133 .PP
1134 lttng is distributed under the GNU General Public License version 2. See the file
1135 COPYING for details.
1136 .PP
1137 A Web site is available at http://lttng.org for more information on the LTTng
1138 project.
1139 .PP
1140 You can also find our git tree at http://git.lttng.org.
1141 .PP
1142 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
1143 .PP
1144 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
1145 .PP
1146 .SH "THANKS"
1147
1148 .PP
1149 Thanks to Yannick Brosseau without whom this project would never have been so
1150 lean and mean! Also thanks to the Ericsson teams working on tracing which
1151 helped us greatly with detailed bug reports and unusual test cases.
1152
1153 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
1154 maintainer) and Jon Bernard for our Debian packages.
1155
1156 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
1157 Montreal for the LTTng journey.
1158 .PP
1159 .SH "AUTHORS"
1160
1161 .PP
1162 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
1163 David Goulet. More people have since contributed to it. It is currently
1164 maintained by Jérémie Galarneau <jeremie.galarneau@efficios.com>.
1165 .PP
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