bd2776114f597df6ec3983990a1a2eaacf239cee
[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 | \-j | \-l | \-p) [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.
594 .TP
595 .BR "\-\-filter 'expression'"
596 Set a filter on a newly enabled event. Filter expression on event
597 fields and context. The event will be recorded if the filter's
598 expression evaluates to TRUE. Only specify on first activation of a
599 given event within a session.
600 Specifying a filter is only allowed when enabling events within a session before
601 tracing is started. If the filter fails to link with the event
602 within the traced domain, the event will be discarded.
603
604 Expression examples:
605
606 .nf
607 'intfield > 500 && intfield < 503'
608 '(strfield == "test" || intfield != 10) && intfield > 33'
609 'doublefield > 1.1 && intfield < 5.3'
610 'enumfield == 1234'
611 .fi
612
613 Wildcards are allowed at the end of strings:
614 'seqfield1 == "te*"'
615 In string literals, the escape character is a '\\'. Use '\\*' for
616 the '*' character, and '\\\\' for the '\\' character sequence. Wildcard
617 matches any sequence of characters, including an empty sub-string
618 (matches 0 or more characters). Enumeration fields can currently only be
619 compared as integers.
620
621 Context information can be used for filtering. The examples below shows
622 usage of context filtering on the process name (using a wildcard), process ID
623 range, and unique thread ID. The process and thread IDs of
624 running applications can be found under columns "PID" and "LWP" of the
625 "ps -eLf" command.
626
627 .nf
628 '$ctx.procname == "demo*"'
629 '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
630 '$ctx.vtid == 1234'
631 .fi
632
633 Context information is available to all filters whether or not the add-context
634 command has been used to add it to the event's channel, as long as the context
635 field exists for that domain. For example, the filter examples given above will
636 never fail to link: no add-context is required for the event's channel.
637
638 .TP
639 .BR "\-x, \-\-exclude LIST"
640 Add exclusions to UST tracepoints:
641 Events that match any of the items in the comma-separated LIST are not
642 enabled, even if they match a wildcard definition of the event.
643
644 This option is also applicable with the \fB\-a, \-\-all\fP option,
645 in which case all UST tracepoints are enabled except the ones whose
646 names match any of the items in LIST.
647 .RE
648 .PP
649
650 .PP
651 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
652 .RS
653 Disable tracing channel
654
655 Disabling a channel disables the tracing of all of the channel's events. A channel
656 can be re-enabled by calling \fBlttng enable-channel NAME\fP again.
657
658 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
659 file.
660
661 .B OPTIONS:
662
663 .TP
664 .BR "\-h, \-\-help"
665 Show summary of possible options and commands.
666 .TP
667 .BR "\-\-list-options"
668 Simple listing of options
669 .TP
670 .BR "\-s, \-\-session NAME"
671 Apply on session name
672 .TP
673 .BR "\-k, \-\-kernel"
674 Apply for the kernel tracer
675 .TP
676 .BR "\-u, \-\-userspace"
677 Apply for the user-space tracer
678 .RE
679 .PP
680
681 .PP
682 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u | \-j | \-l | \-p) [TYPE] [OPTIONS]
683 .RS
684 Disable tracing event
685
686 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
687 NAME\fP again.
688
689 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
690 file.
691
692 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
693 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
694 exists within the session, an error is returned.
695
696 .B OPTIONS:
697
698 .TP
699 .BR "\-h, \-\-help"
700 Show summary of possible options and commands.
701 .TP
702 .BR "\-\-list-options"
703 Simple listing of options
704 .TP
705 .BR "\-s, \-\-session NAME"
706 Apply on session name
707 .TP
708 .BR "\-c, \-\-channel NAME"
709 Apply on channel name
710 .TP
711 .BR "\-a, \-\-all-events"
712 Disable all events. This does NOT ONLY disable "*" but rather every known
713 events of the session
714 .TP
715 .BR "\-k, \-\-kernel"
716 Apply for the kernel tracer
717 .TP
718 .BR "\-u, \-\-userspace"
719 Apply for the user-space tracer
720 .TP
721 .BR "\-j, \-\-jul"
722 Apply for Java application using Java Util Logging interface (JUL)
723 .TP
724 .BR "\-l, \-\-log4j"
725 Apply for Java application using LOG4J
726 .TP
727 .BR "\-p, \-\-python"
728 Apply for Python application using the logging module
729
730 .TP
731 .B TYPE (kernel domain only):
732
733 .TP
734 .BR "\-\-all"
735 Disable event of all type
736 .TP
737 .BR "\-\-tracepoint"
738 Disable event of type tracepoint
739 .TP
740 .BR "\-\-syscall"
741 Disable event of type syscall
742 .TP
743 .BR "\-\-probe"
744 Disable event of type probe
745 .TP
746 .BR "\-\-function"
747 Disable event of type function
748 .RE
749 .PP
750
751 .PP
752 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
753 .RS
754 List tracing session information.
755
756 With no arguments, it will list available tracing session(s).
757
758 With the session name, it will display the details of the session including
759 the trace file path, the associated channels and their state (activated
760 and deactivated), the activated events and more.
761
762 With \-k alone, it will list all available kernel events (except the system
763 calls events).
764 With \-j alone, the available JUL event from registered application will be
765 list. The event corresponds to the Logger name in the Java JUL application.
766 With \-l alone, the available LOG4J event from registered application will be
767 list. The event corresponds to the Logger name in the Java LOG4J application.
768 With \-p alone, the available Python event from registered application will be
769 list. The event corresponds to the Logger name in the Python application.
770 With \-u alone, it will list all available user-space events from registered
771 applications. Here is an example of 'lttng list \-u':
772
773 .nf
774 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
775 ust_tests_hello:tptest_sighandler (type: tracepoint)
776 ust_tests_hello:tptest (type: tracepoint)
777 .fi
778
779 You can now enable any event listed by using the name :
780 \fBust_tests_hello:tptest\fP.
781
782 .B OPTIONS:
783
784 .TP
785 .BR "\-h, \-\-help"
786 Show summary of possible options and commands.
787 .TP
788 .BR "\-\-list-options"
789 Simple listing of options
790 .TP
791 .BR "\-k, \-\-kernel"
792 Select kernel domain
793 .TP
794 .BR "\-u, \-\-userspace"
795 Select user-space domain.
796 .TP
797 .BR "\-j, \-\-jul"
798 Apply for Java application using JUL
799 .TP
800 .BR "\-l, \-\-log4j"
801 Apply for Java application using LOG4J
802 .TP
803 .BR "\-p, \-\-python"
804 Apply for Python application using the logging module.
805 .TP
806 .BR "\-f, \-\-fields"
807 List event fields
808
809 .PP
810 .B SESSION OPTIONS:
811
812 .TP
813 .BR "\-c, \-\-channel NAME"
814 List details of a channel
815 .TP
816 .BR "\-d, \-\-domain"
817 List available domain(s)
818 .RE
819 .PP
820
821 .PP
822 \fBload\fP [OPTIONS] [NAME]
823 .RS
824 Load tracing session configuration
825
826 If NAME is omitted, all session configurations found in both the user's session
827 configuration directory (default: ~/.lttng/sessions/) and the system session
828 configuration directory (default: /etc/lttng/sessions/) will be loaded. Note
829 that the sessions in the user directory are loaded first and then the system
830 wide directory are loaded.
831
832 .B OPTIONS:
833
834 .TP
835 .BR "\-h, \-\-help"
836 Show summary of possible options and commands.
837 .TP
838 .BR "\-a, \-\-all"
839 Load all session configurations (default).
840 .TP
841 .BR "\-i, \-\-input-path PATH"
842 Specify the input path for session configurations. This overrides the default
843 session configuration directory.
844 .TP
845 .BR "\-f, -\-force"
846 Overwrite current session configuration(s) if a session of the same name
847 already exists.
848 .RE
849 .PP
850
851 .PP
852 \fBmetadata\fP [OPTIONS] ACTION
853 .RS
854 Metadata command for a LTTng session.
855
856 .B OPTIONS:
857
858 .TP
859 .BR "\-h, \-\-help"
860 Show summary of possible options and commands.
861 .TP
862 .BR "\-\-list-options"
863 Simple listing of options
864
865 .PP
866 .B ACTION:
867
868 .TP
869 \fBregenerate\fP [-s <NAME>]
870 Regenerate the metadata of a session. This allows the user to regenerate the
871 metadata after a major NTP correction and that way update the clock offset from
872 epoch in the metadata. Only works on kernel, UST per-uid and non-live sessions.
873 .RE
874 .PP
875
876 .PP
877 \fBsave\fP [OPTIONS] [SESSION]
878 .RS
879 Save tracing session configuration
880
881 If SESSION is omitted, all session configurations will be saved to individual
882 \fB.lttng\fP files under the user's session configuration directory (default:
883 ~/.lttng/sessions/). The default session configuration file naming scheme is
884 \fBSESSION.lttng\fP.
885
886 For instance, a user in the tracing group saving a session from a root session
887 daemon will save it in her/his user directory.
888
889 .B OPTIONS:
890
891 .TP
892 .BR "\-h, \-\-help"
893 Show summary of possible options and commands.
894 .TP
895 .BR "\-a, \-\-all"
896 Save all session configurations (default).
897 .TP
898 .BR "\-o, \-\-output-path PATH"
899 Specify the output path for saved sessions. This overrides the default session
900 configuration directory.
901 .TP
902 .BR "\-f, -\-force"
903 Overwrite session configuration file if session name clashes.
904 .RE
905 .PP
906
907 .PP
908 \fBset-session\fP NAME [OPTIONS]
909 .RS
910 Set current session name
911
912 Will change the session name in the .lttngrc file.
913
914 .B OPTIONS:
915
916 .TP
917 .BR "\-h, \-\-help"
918 Show summary of possible options and commands.
919 .TP
920 .BR "\-\-list-options"
921 Simple listing of options
922 .RE
923 .PP
924
925 .PP
926 \fBsnapshot\fP [OPTIONS] ACTION
927 .RS
928 Snapshot command for LTTng session.
929
930 .B OPTIONS:
931
932 .TP
933 .BR "\-h, \-\-help"
934 Show summary of possible options and commands.
935 .TP
936 .BR "\-\-list-options"
937 Simple listing of options
938
939 .PP
940 .B ACTION:
941
942 .TP
943 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
944
945 Setup and add a snapshot output for a session. Output is the destination
946 where the snapshot will be sent. Only one output is permitted. To change it,
947 you'll need to delete it and add back the new one.
948
949 .TP
950 \fBdel-output\fP ID | NAME [-s <NAME>]
951
952 Delete an output for a session using the output's ID. You can either specify the
953 output by name or use its ID as returned by the list-output command.
954
955 .TP
956 \fBlist-output\fP [-s <NAME>]
957
958 List the output of a session. Attributes of the output are printed.
959
960 .TP
961 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
962
963 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
964 used instead of a previously added output. Specifying only a name or/and a max
965 size will override the current output values. For instance, you can record a
966 snapshot with a custom maximum size or with a different name.
967
968 .nf
969 $ lttng snapshot add-output -n mysnapshot file:///data/snapshot
970 [...]
971 $ lttng snapshot record -n new_name_snapshot
972 .fi
973
974 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
975 rather then in mysnapshot*/
976
977 .PP
978 .B DETAILED ACTION OPTIONS
979
980 .TP
981 .BR "\-s, \-\-session NAME"
982 Apply to session name.
983 .TP
984 .BR "\-n, \-\-name NAME"
985 Name of the snapshot's output.
986 .TP
987 .BR "\-m, \-\-max-size SIZE"
988 Maximum size in bytes of the snapshot. The maximum size does not include the
989 metadata file. Human readable format is accepted: {+k,+M,+G}. For instance,
990 \-\-max-size 5M
991 .TP
992 .BR "\-C, \-\-ctrl-url URL"
993 Set control path URL. (Must use -D also)
994 .TP
995 .BR "\-D, \-\-data-url URL"
996 Set data path URL. (Must use -C also)
997 .RE
998 .PP
999
1000 .PP
1001 \fBstart\fP [NAME] [OPTIONS]
1002 .RS
1003 Start tracing
1004
1005 It will start tracing for all tracers for a specific tracing session.
1006 If NAME is omitted, the session name is taken from the .lttngrc file.
1007
1008 .B OPTIONS:
1009
1010 .TP
1011 .BR "\-h, \-\-help"
1012 Show summary of possible options and commands.
1013 .TP
1014 .BR "\-\-list-options"
1015 Simple listing of options
1016 .RE
1017 .PP
1018
1019 .PP
1020 \fBstop\fP [NAME] [OPTIONS]
1021 .RS
1022 Stop tracing
1023
1024 It will stop tracing for all tracers for a specific tracing session. Before
1025 returning, the command checks for data availability meaning that it will wait
1026 until the trace is readable for the session. Use \-\-no-wait to avoid this
1027 behavior.
1028
1029 If NAME is omitted, the session name is taken from the .lttngrc file.
1030
1031 .B OPTIONS:
1032
1033 .TP
1034 .BR "\-h, \-\-help"
1035 Show summary of possible options and commands.
1036 .TP
1037 .BR "\-\-list-options"
1038 Simple listing of options
1039 .TP
1040 .BR "\-\-no-wait"
1041 Don't wait for data availability.
1042 .RE
1043 .PP
1044
1045 .PP
1046 \fBtrack\fP (-k | -u) --pid [PID1[,PID2[,...]]] [OPTIONS]
1047 .RS
1048 Adds one or more entries to a tracker
1049
1050 The \fBtrack\fP command adds one or more entries to a tracker. A tracker is
1051 a whitelist of resources. Tracked resources are allowed to emit events, provided
1052 those events are enabled (see the \fBenable-event\fP command).
1053
1054 Tracker entries can be removed from the whitelist with the
1055 \fBuntrack\fP command.
1056
1057 As of this version, the only available tracker is the \fBPID tracker\fP. The
1058 process ID (PID) tracker follows one or more process IDs;
1059 only the processes with a tracked PID are allowed to emit events. By default,
1060 all possible PIDs on the system are tracked: any process may emit enabled
1061 events (equivalent of \fBlttng track \-\-pid \-\-all\fR for all domains).
1062
1063 With the PID tracker, it is possible, for example, to record all system calls
1064 called by a given process:
1065
1066 .nf
1067 $ lttng enable-event --kernel --all --syscall
1068 $ lttng track --kernel --pid 2345
1069 $ lttng start
1070 .fi
1071
1072 If all the PIDs are tracked (i.e. \fBlttng track \-\-pid \-\-all\fR, which
1073 is the default state of all domains when creating a tracing session), then
1074 using the \fBtrack\fR command with one or more specific PIDs has the effect of
1075 first removing all the PIDs from the whitelist, then adding the specified PIDs.
1076
1077 Assume the maximum PID is 7 for the following examples:
1078
1079 .nf
1080 Initial whitelist: [0] [1] [2] [3] [4] [5] [6] [7]
1081
1082 $ lttng track --userspace --pid 3,6,7
1083
1084 Whitelist: [ ] [ ] [ ] [3] [ ] [ ] [6] [7]
1085
1086 $ lttng untrack --userspace --pid 7
1087
1088 Whitelist: [ ] [ ] [ ] [3] [ ] [ ] [6] [ ]
1089
1090 $ lttng track --userspace --pid 1,5
1091
1092 Whitelist: [ ] [1] [ ] [3] [ ] [5] [6] [ ]
1093 .fi
1094
1095 It should be noted that the PID tracker tracks the numeric process IDs.
1096 Should a process with a given ID exit and another process be given this
1097 ID, then the latter would also be allowed to emit events.
1098
1099 See the \fBuntrack\fR command's documentation for more details about
1100 removing entries.
1101
1102 .B OPTIONS:
1103
1104 .TP
1105 .BR "\-s, \-\-session NAME"
1106 Apply to session name.
1107 .TP
1108 .BR "\-k, \-\-kernel"
1109 Apply to the kernel tracer.
1110 .TP
1111 .BR "\-u, \-\-userspace"
1112 Apply to the user space tracer.
1113 .TP
1114 .BR "\-p, \-\-pid [PIDS]"
1115 Track process IDs PIDS (add to whitelist).
1116
1117 PIDS is a comma-separated list of PIDs to add to the PID tracker.
1118
1119 The PIDS argument must be omitted when also using the \fB\-\-all\fP option.
1120 .TP
1121 .BR "\-a, \-\-all"
1122 Used in conjunction with an empty \fB\-\-pid\fP option: track all process IDs
1123 (add all entries to whitelist).
1124 .TP
1125 .BR "\-h, \-\-help"
1126 Show summary of possible options and commands.
1127 .TP
1128 .BR "\-\-list-options"
1129 Simple listing of options
1130 .RE
1131 .PP
1132
1133 .PP
1134 \fBuntrack\fP (-k | -u) --pid [PID1[,PID2[,...]]] [OPTIONS]
1135 .RS
1136 Removes one or more entries from a tracker
1137
1138 See the \fBtrack\fP command's documentation to learn more about LTTng
1139 trackers.
1140
1141 The \fBuntrack\fP command removes specific resources from a tracker. The
1142 resources to remove must have been precedently added by the
1143 \fBtrack\fP command. It is also possible to remove all the resources
1144 from the whitelist using the \fB\-\-all\fR option.
1145
1146 As of this version, the only available tracker is the \fBPID tracker\fP.
1147
1148 One common operation is to create a tracing session, remove all the entries
1149 from the PID tracker whitelist, start tracing, and then manually track PIDs
1150 while tracing is active.
1151
1152 Assume the maximum PID is 7 for the following examples:
1153
1154 .nf
1155 $ lttng create
1156
1157 Initial whitelist: [0] [1] [2] [3] [4] [5] [6] [7]
1158
1159 $ lttng untrack --userspace --pid --all
1160
1161 Whitelist: [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
1162
1163 $ lttng enable-event --userspace ...
1164 $ lttng start
1165 ...
1166 $ lttng track --userspace --pid 3,5
1167
1168 Whitelist: [ ] [ ] [ ] [3] [ ] [5] [ ] [ ]
1169
1170 $ lttng track --userspace --pid 2
1171
1172 Whitelist: [ ] [ ] [2] [3] [ ] [5] [ ] [ ]
1173 .fi
1174
1175 See the \fBtrack\fR command's documentation for more details about
1176 adding entries.
1177
1178 .B OPTIONS:
1179
1180 .TP
1181 .BR "\-s, \-\-session NAME"
1182 Apply to session name.
1183 .TP
1184 .BR "\-k, \-\-kernel"
1185 Apply to the kernel tracer.
1186 .TP
1187 .BR "\-u, \-\-userspace"
1188 Apply to the user space tracer.
1189 .TP
1190 .BR "\-p, \-\-pid [PIDS]"
1191 Stop tracking process IDs PIDS (remove from whitelist).
1192
1193 PIDS is a comma-separated list of PIDs to remove from the PID tracker.
1194
1195 The PIDS argument must be omitted when also using the \fB\-\-all\fP option.
1196 .TP
1197 .BR "\-a, \-\-all"
1198 Used in conjunction with an empty \fB\-\-pid\fP option: stop tracking all
1199 process IDs (remove all entries from whitelist).
1200 .TP
1201 .BR "\-h, \-\-help"
1202 Show summary of possible options and commands.
1203 .TP
1204 .BR "\-\-list-options"
1205 Simple listing of options
1206 .RE
1207 .PP
1208
1209 .PP
1210 \fBversion\fP
1211 .RS
1212 Show version information
1213
1214 .B OPTIONS:
1215
1216 .TP
1217 .BR "\-h, \-\-help"
1218 Show summary of possible options and commands.
1219 .TP
1220 .BR "\-\-list-options"
1221 Simple listing of options
1222 .RE
1223 .PP
1224
1225 .PP
1226 \fBview\fP [SESSION_NAME] [OPTIONS]
1227 .RS
1228 View traces of a tracing session. By default, the babeltrace viewer
1229 will be used for text viewing. If SESSION_NAME is omitted, the session
1230 name is taken from the .lttngrc file.
1231
1232 .B OPTIONS:
1233
1234 .TP
1235 .BR "\-h, \-\-help"
1236 Show this help
1237 .TP
1238 .BR "\-\-list-options"
1239 Simple listing of options
1240 .TP
1241 .BR "\-t, \-\-trace-path PATH"
1242 Trace directory path for the viewer
1243 .TP
1244 .BR "\-e, \-\-viewer CMD"
1245 Specify viewer and/or options to use This will completely override the
1246 default viewers so please make sure to specify the full command. The
1247 trace directory path of the session will be appended at the end to the
1248 arguments
1249 .RE
1250 .PP
1251
1252 .SH "JUL/LOG4J DOMAIN"
1253
1254 This section explains the JUL and LOG4J domain where JUL stands for Java Util
1255 Logging. You can use these by using the \fBliblttng-ust-<domain>-jni.so\fP from
1256 the lttng-ust(3) project.
1257
1258 The LTTng Java Agent uses JNI to link the UST tracer to the Java application
1259 that uses the agent. Thus, it behaves similarly to the UST domain (\-u). When
1260 enabling events, you enable a Logger name that will then be mapped to a default
1261 UST tracepoint called \fBlttng_jul:<domain>_event\fP in the
1262 \fBlttng_<domain>_channel\fP. Using the lttng-ctl API, any JUL/LOG4J events
1263 must use the tracepoint event type (same as \-\-tracepoint).
1264
1265 Because of the default immutable channel, the \fBenable-channel\fP command CAN
1266 NOT be used with the JUL and LOG4J domain thus not having any options.
1267
1268 Also, loglevels are supported. Use \fBlttng enable-event \-h\fP to list them.
1269 Wildcards are NOT supported except the "*" meaning all events (same as \-a).
1270
1271 Exactly like the UST domain, if the Java application has the same UID as you,
1272 you can trace it. Same goes for the tracing group accessing root applications.
1273
1274 Finally, you can list every Logger name that are available from registered
1275 applications to the session daemon by using \fBlttng list \-j\fP or \fB\-l\fP.
1276
1277 Here is an example on how to use the JUL domain.
1278
1279 .nf
1280 $ lttng list -j
1281 [...]
1282 $ lttng create aSession
1283 $ lttng enable-event -s aSession -j MyCustomLoggerName
1284 $ lttng start
1285 .fi
1286
1287 More information can be found in the lttng-ust documentation, see
1288 java-util-logging.txt
1289 .PP
1290
1291 .SH "EXIT VALUES"
1292 .PP
1293 On success 0 is returned and a positive value on error. Value of 1 means a command
1294 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
1295 something went wrong during the command.
1296
1297 Any other value above 10, please refer to
1298 .BR "<lttng/lttng-error.h>"
1299 for a detailed list or use lttng_strerror() to get a human readable string of
1300 the error code.
1301 .PP
1302
1303 .SH "ENVIRONMENT VARIABLES"
1304
1305 .PP
1306 Note that all command line options override environment variables.
1307 .PP
1308
1309 .PP
1310 .IP "LTTNG_SESSIOND_PATH"
1311 Allows one to specify the full session daemon binary path to lttng command line
1312 tool. You can also use \-\-sessiond-path option having the same effect.
1313 .PP
1314
1315 .PP
1316 .IP "LTTNG_SESSION_CONFIG_XSD_PATH"
1317 Set the path in which the \fBsession.xsd\fP session configuration schema may be
1318 found.
1319 .PP
1320
1321 .SH "SEE ALSO"
1322 .BR babeltrace(1),
1323 .BR lttng-ust(3),
1324 .BR lttng-sessiond(8),
1325 .BR lttng-relayd(8),
1326 .BR lttng-crash(1),
1327
1328 .SH "BUGS"
1329
1330 .PP
1331 If you encounter any issues or usability problem, please report it on our
1332 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
1333 at https://bugs.lttng.org which is a bug tracker.
1334 .PP
1335
1336 .SH "CREDITS"
1337
1338 .PP
1339 lttng is distributed under the GNU General Public License version 2. See the file
1340 COPYING for details.
1341 .PP
1342 A Web site is available at http://lttng.org for more information on the LTTng
1343 project.
1344 .PP
1345 You can also find our git tree at http://git.lttng.org.
1346 .PP
1347 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
1348 .PP
1349 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
1350 .PP
1351 .SH "THANKS"
1352
1353 .PP
1354 Thanks to Yannick Brosseau without whom this project would never have been so
1355 lean and mean! Also thanks to the Ericsson teams working on tracing which
1356 helped us greatly with detailed bug reports and unusual test cases.
1357
1358 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
1359 maintainer) and Jon Bernard for our Debian packages.
1360
1361 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
1362 Montreal for the LTTng journey.
1363 .PP
1364 .SH "AUTHORS"
1365
1366 .PP
1367 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
1368 David Goulet. More people have since contributed to it. It is currently
1369 maintained by Jérémie Galarneau <jeremie.galarneau@efficios.com>.
1370 .PP
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