doc/man/lttng.1

   1 .TH "LTTNG" "1" "July 18th, 2013" "" ""
   2
   3 .SH "NAME"
   4 lttng \(em 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 It's tracers help tracking down performance issues and debugging 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 interactions with the tracer should
  20 be done by this tool or by the liblttng-ctl provided with 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 or user space for now). In the future, we could see a third
  31 tracer being for instance an hypervisor. For some commands, you'll need to
  32 specify on which domain the command applies (-u or -k). For instance, enabling
  33 a kernel event, you must specify the kernel domain to the command so we know
  34 for which tracer this event is for.
  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 to start the session
  42 daemon at boot time for stable and long term tracing.
  43
  44 Every user-space applications instrumented with lttng-ust(3), will
  45 automatically register to the session daemon. This feature gives you the
  46 ability to list available traceable applications and tracepoints on a per user
  47 basis. (See \fBlist\fP command).
  48 .SH "OPTIONS"
  49
  50 .PP
  51 This program follow the usual GNU command line syntax with long options starting with
  52 two dashes. Below is a summary of the available options.
  53 .PP
  54
  55 .TP
  56 .BR "\-h, \-\-help"
  57 Show summary of possible options and commands.
  58 .TP
  59 .BR "\-v, \-\-verbose"
  60 Increase verbosity.
  61 Three levels of verbosity are available which are triggered by putting additional v to
  62 the option (\-vv or \-vvv)
  63 .TP
  64 .BR "\-q, \-\-quiet"
  65 Suppress all messages (even errors).
  66 .TP
  67 .BR "\-g, \-\-group NAME"
  68 Set unix tracing group name. (default: tracing)
  69 .TP
  70 .BR "\-n, \-\-no-sessiond"
  71 Don't automatically spawn a session daemon.
  72 .TP
  73 .BR "\-\-sessiond\-path PATH"
  74 Set session daemon full binary path.
  75 .TP
  76 .BR "\-\-list\-options"
  77 Simple listing of lttng options.
  78 .TP
  79 .BR "\-\-list\-commands"
  80 Simple listing of lttng commands.
  81 .SH "COMMANDS"
  82
  83 .PP
  84 \fBadd-context\fP [OPTIONS]
  85 .RS
  86 Add context to event(s) and/or channel(s).
  87
  88 A context is basically extra information appended to a channel. For instance,
  89 you could ask the tracer to add the PID information for all events in a
  90 channel. You can also add performance monitoring unit counters (perf PMU) using
  91 the perf kernel API).
  92
  93 For example, this command will add the context information 'prio' and two perf
  94 counters (hardware branch misses and cache misses), to all events in the trace
  95 data output:
  96
  97 .nf
  98 # lttng add-context \-k \-t prio \-t perf:branch-misses \\
  99                 \-t perf:cache-misses
 100 .fi
 101
 102 Please take a look at the help (\-h/\-\-help) for a detailed list of available
 103 contexts.
 104
 105 If no channel is given (\-c), the context is added to all channels that were
 106 already enabled. If the session has no channel, a default channel is created.
 107 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
 108 exists within the session, an error is returned.  Otherwise the context
 109 will be added only to the given channel (\-c).
 110
 111 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 112 file.
 113
 114 .B OPTIONS:
 115
 116 .TP
 117 .BR "\-h, \-\-help"
 118 Show summary of possible options and commands.
 119 .TP
 120 .BR "\-s, \-\-session NAME"
 121 Apply on session name.
 122 .TP
 123 .BR "\-c, \-\-channel NAME"
 124 Apply on channel name.
 125 .TP
 126 .BR "\-k, \-\-kernel"
 127 Apply for the kernel tracer
 128 .TP
 129 .BR "\-u, \-\-userspace"
 130 Apply for the user-space tracer
 131 .TP
 132 .BR "\-t, \-\-type TYPE"
 133 Context type. You can repeat this option on the command line. Please
 134 use "lttng add-context \-h" to list all available types.
 135 .RE
 136 .PP
 137
 138 .PP
 139 \fBcalibrate\fP [OPTIONS]
 140 .RS
 141 Quantify LTTng overhead
 142
 143 The LTTng calibrate command can be used to find out the combined average
 144 overhead of the LTTng tracer and the instrumentation mechanisms used. This
 145 overhead can be calibrated in terms of time or using any of the PMU performance
 146 counter available on the system.
 147
 148 For now, the only calibration implemented is that of the kernel function
 149 instrumentation (kretprobes).
 150
 151 * Calibrate kernel function instrumentation
 152
 153 Let's use an example to show this calibration. We use an i7 processor with 4
 154 general-purpose PMU registers. This information is available by issuing dmesg,
 155 looking for "generic registers".
 156
 157 This sequence of commands will gather a trace executing a kretprobe hooked on
 158 an empty function, gathering PMU counters LLC (Last Level Cache) misses
 159 information (see lttng add-context \-\-help to see the list of available PMU
 160 counters).
 161
 162 .nf
 163 # lttng create calibrate-function
 164 # lttng enable-event calibrate \-\-kernel \\
 165         \-\-function lttng_calibrate_kretprobe
 166 # lttng add-context \-\-kernel \-t perf:LLC-load-misses \\
 167         \-t perf:LLC-store-misses \\
 168         \-t perf:LLC-prefetch-misses
 169 # lttng start
 170 # for a in $(seq 1 10); do \\
 171         lttng calibrate \-\-kernel \-\-function;
 172   done
 173 # lttng destroy
 174 # babeltrace $(ls \-1drt ~/lttng-traces/calibrate-function-* \\
 175         | tail \-n 1)
 176 .fi
 177
 178 The output from babeltrace can be saved to a text file and opened in a
 179 spreadsheet (e.g. oocalc) to focus on the per-PMU counter delta between
 180 consecutive "calibrate_entry" and "calibrate_return" events. Note that these
 181 counters are per-CPU, so scheduling events would need to be present to account
 182 for migration between CPU. Therefore, for calibration purposes, only events
 183 staying on the same CPU must be considered.
 184
 185 The average result, for the i7, on 10 samples:
 186
 187 .nf
 188                           Average     Std.Dev.
 189 perf_LLC_load_misses:       5.0       0.577
 190 perf_LLC_store_misses:      1.6       0.516
 191 perf_LLC_prefetch_misses:   9.0      14.742
 192 .fi
 193
 194 As we can notice, the load and store misses are relatively stable across runs
 195 (their standard deviation is relatively low) compared to the prefetch misses.
 196 We can conclude from this information that LLC load and store misses can be
 197 accounted for quite precisely, but prefetches within a function seems to behave
 198 too erratically (not much causality link between the code executed and the CPU
 199 prefetch activity) to be accounted for.
 200
 201 .B OPTIONS:
 202
 203 .TP
 204 .BR "\-h, \-\-help"
 205 Show summary of possible options and commands.
 206 .TP
 207 .BR "\-k, \-\-kernel"
 208 Apply for the kernel tracer
 209 .TP
 210 .BR "\-u, \-\-userspace"
 211 Apply for the user-space tracer
 212 .TP
 213 .BR "\-\-function"
 214 Dynamic function entry/return probe (default)
 215 .RE
 216 .PP
 217
 218 .PP
 219 .IP \fBcreate\fP [NAME] [OPTIONS]
 220 .RS
 221 Create tracing session.
 222
 223 A tracing session contains channel(s) which contains event(s). It is domain
 224 agnostic meaning that you can enable channels and events for either the
 225 user-space tracer and/or the kernel tracer. It acts like a container
 226 aggregating multiple tracing sources.
 227
 228 On creation, a \fB.lttngrc\fP file is created in your $HOME directory
 229 containing the current session name. If NAME is omitted, a session name is
 230 automatically created having this form: 'auto-yyyymmdd-hhmmss'.
 231
 232 If no \fB\-o, \-\-output\fP is specified, the traces will be written in
 233 $HOME/lttng-traces.
 234
 235 The $HOME environment variable can be overridden by defining the environment
 236 variable LTTNG_HOME. This is useful when the user running the commands has
 237 a non-writeable home directory.
 238
 239 .B OPTIONS:
 240
 241 .TP
 242 .BR "\-h, \-\-help"
 243 Show summary of possible options and commands.
 244 .TP
 245 .BR "\-\-list-options"
 246 Simple listing of options
 247 .TP
 248 .BR "\-o, \-\-output PATH"
 249 Specify output path for traces
 250 .TP
 251 .BR "\-\-no-output"
 252 Traces will not be outputed
 253 .TP
 254 .BR "\-\-snapshot"
 255 Set the session in snapshot mode. Created in no-output mode and uses the
 256 URL, if one, as the default snapshot output.  Every channel will be set
 257 in overwrite mode and with mmap output (splice not supported).
 258
 259 .TP
 260 .BR "\-U, \-\-set-url=URL"
 261 Set URL for the consumer output destination. It is persistent for the
 262 session lifetime. Redo the command to change it. This will set both data
 263 and control URL for network.
 264 .TP
 265 .BR "\-C, \-\-ctrl-url=URL"
 266 Set control path URL. (Must use -D also)
 267 .TP
 268 .BR "\-D, \-\-data-url=URL"
 269 Set data path URL. (Must use -C also)
 270 .PP
 271 Using these options, each API call can be controlled individually. For
 272 instance, \-C does not enable the consumer automatically. You'll need the \-e
 273 option for that.
 274
 275 .B URL FORMAT:
 276
 277 proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]
 278
 279 Supported protocols are (proto):
 280 .TP
 281 .BR "file://..."
 282 Local filesystem full path.
 283
 284 .TP
 285 .BR "net://..."
 286 This will use the default network transport layer which is TCP for both
 287 control (PORT1) and data port (PORT2). The default ports are
 288 respectively 5342 and 5343. Note that net[6]:// is not yet supported.
 289
 290 .TP
 291 .BR "tcp[6]://..."
 292 Can only be used with -C and -D together
 293
 294 NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)
 295
 296 .B EXAMPLES:
 297
 298 .nf
 299 # lttng create -U net://192.168.1.42
 300 .fi
 301 Uses TCP and default ports for the given destination.
 302
 303 .nf
 304 # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]
 305 .fi
 306 Uses TCP, default ports and IPv6.
 307
 308 .nf
 309 # lttng create s1 -U net://myhost.com:3229
 310 .fi
 311 Create session s1 and set its consumer to myhost.com on port 3229 for control.
 312 .RE
 313 .PP
 314
 315 .PP
 316 \fBdestroy\fP [NAME] [OPTIONS]
 317 .RS
 318 Teardown tracing session
 319
 320 Free memory on the session daemon and tracer side. It's gone!
 321
 322 If NAME is omitted, the session name is taken from the .lttngrc file.
 323
 324 .B OPTIONS:
 325
 326 .TP
 327 .BR "\-h, \-\-help"
 328 Show summary of possible options and commands.
 329 .TP
 330 .BR "\-a, \-\-all"
 331 Destroy all sessions
 332 .TP
 333 .BR "\-\-list-options"
 334 Simple listing of options
 335 .RE
 336 .PP
 337
 338 .PP
 339 \fBenable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
 340 .RS
 341 Enable tracing channel
 342
 343 To enable an event, you must enable both the event and the channel that
 344 contains it.
 345
 346 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 347 file.
 348
 349 Exactly one of \-k or -u must be specified.
 350
 351 It is important to note that if a certain type of buffers is used, the session
 352 will be set with that type and all other subsequent channel needs to have the
 353 same type.
 354
 355 Note that once the session has been started and enabled on the tracer side,
 356 it's not possible anymore to enable a new channel for that session.
 357
 358 .B OPTIONS:
 359
 360 .TP
 361 .BR "\-h, \-\-help"
 362 Show this help
 363 .TP
 364 .BR "\-\-list-options"
 365 Simple listing of options
 366 .TP
 367 .BR "\-s, \-\-session NAME"
 368 Apply on session name
 369 .TP
 370 .BR "\-k, \-\-kernel"
 371 Apply to the kernel tracer
 372 .TP
 373 .BR "\-u, \-\-userspace"
 374 Apply to the user-space tracer
 375 .TP
 376 .BR "\-\-discard"
 377 Discard event when subbuffers are full (default)
 378 .TP
 379 .BR "\-\-overwrite"
 380 Flight recorder mode : overwrites events when subbuffers are full
 381 .TP
 382 .BR "\-\-subbuf-size SIZE"
 383 Subbuffer size in bytes {+k,+M,+G}.
 384 (default UST uid: 131072, UST pid: 4096, kernel: 262144, metadata: 4096)
 385 Rounded up to the next power of 2.
 386
 387 The minimum subbuffer size, for each tracer, is the max value between
 388 the default above and the system page size. You can issue this command
 389 to get the current page size on your system: \fB$ getconf PAGE_SIZE\fP
 390 .TP
 391 .BR "\-\-num-subbuf NUM"
 392 Number of subbuffers. (default UST uid: 4, UST pid: 4, kernel: 4,
 393 metadata: 2) Rounded up to the next power of 2.
 394 .TP
 395 .BR "\-\-switch-timer USEC"
 396 Switch subbuffer timer interval in µsec.
 397 (default UST uid: 0, UST pid: 0, kernel: 0, metadata: 0)
 398 .TP
 399 .BR "\-\-read-timer USEC"
 400 Read timer interval in µsec.
 401 (default UST uid: 0, UST pid: 0, kernel: 200000, metadata: 0)
 402 .TP
 403 .BR "\-\-output TYPE"
 404 Channel output type. Possible values: mmap, splice
 405 (default UST uid: mmap, UST pid: mmap, kernel: splice, metadata: mmap)
 406 .TP
 407 .BR "\-\-buffers-uid"
 408 Use per UID buffer (\-u only). Buffers are shared between applications
 409 that have the same UID.
 410 .TP
 411 .BR "\-\-buffers-pid"
 412 Use per PID buffer (\-u only). Each application has its own buffers.
 413 .TP
 414 .BR "\-\-buffers-global"
 415 Use shared buffer for the whole system (\-k only)
 416 .TP
 417 .BR "\-C, \-\-tracefile-size SIZE"
 418 Maximum size of each tracefile within a stream (in bytes).
 419 0 means unlimited. (default: 0)
 420 .TP
 421 .BR "\-W, \-\-tracefile-count COUNT"
 422 Used in conjunction with \-C option, this will limit the number of files
 423 created to the specified count. 0 means unlimited. (default: 0)
 424
 425 .B EXAMPLES:
 426
 427 .nf
 428 $ lttng enable-channel -k -C 4096 -W 32 chan1
 429 .fi
 430 For each stream, the maximum size of each trace file will be 4096 bytes, and
 431 there will be a maximum of 32 different files. The file count is appended after
 432 the stream number as seen in the following example. The last trace file is
 433 smaller than 4096 since it was not completely filled.
 434
 435 .nf
 436         ~/lttng-traces/[...]/chan1_0_0 (4096)
 437         ~/lttng-traces/[...]/chan1_0_1 (4096)
 438         ~/lttng-traces/[...]/chan1_0_2 (3245)
 439         ~/lttng-traces/[...]/chan1_1_0 (4096)
 440         ...
 441 .fi
 442
 443 .nf
 444 $ lttng enable-channel -k -C 4096
 445 .fi
 446 This will create trace files of 4096 bytes and will create new ones as long as
 447 there is data available.
 448 .RE
 449 .PP
 450
 451 .PP
 452 \fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]
 453 .RS
 454 Enable tracing event
 455
 456 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
 457 omitted, a default channel named '\fBchannel0\fP' is created and the event is
 458 added to it. If \fB\-c, \-\-channel\fP is omitted, but a non-default
 459 channel already exists within the session, an error is returned. For the
 460 user-space tracer, using \fB\-a, \-\-all\fP is the same as using the
 461 wildcard "*".
 462
 463 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 464 file.
 465
 466 .B OPTIONS:
 467
 468 .TP
 469 .BR "\-h, \-\-help"
 470 Show summary of possible options and commands.
 471 .TP
 472 .BR "\-\-list-options"
 473 Simple listing of options
 474 .TP
 475 .BR "\-s, \-\-session NAME"
 476 Apply on session name
 477 .TP
 478 .BR "\-c, \-\-channel NAME"
 479 Apply on channel name
 480 .TP
 481 .BR "\-a, \-\-all"
 482 Enable all tracepoints and syscalls. This actually enable a single
 483 wildcard event "*".
 484 .TP
 485 .BR "\-k, \-\-kernel"
 486 Apply for the kernel tracer
 487 .TP
 488 .BR "\-u, \-\-userspace"
 489 Apply for the user-space tracer
 490 .TP
 491 .BR "\-\-tracepoint"
 492 Tracepoint event (default). Userspace tracer supports wildcards at end
 493 of string. Don't forget to quote to deal with bash expansion.
 494 e.g.:
 495 .nf
 496         "*"
 497         "app_component:na*"
 498 .fi
 499 .TP
 500 .BR "\-\-loglevel NAME"
 501 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
 502 .TP
 503 .BR "\-\-loglevel-only NAME"
 504 Tracepoint loglevel (only this loglevel).
 505 The loglevel or loglevel-only options should be combined with a
 506 tracepoint name or tracepoint wildcard.
 507 .TP
 508 .BR "\-\-probe (addr | symbol | symbol+offset)"
 509 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
 510 or hexadecimal (0xNNN...)
 511 .TP
 512 .BR "\-\-function (addr | symbol | symbol+offset)"
 513 Dynamic function entry/return probe. Addr and offset can be octal
 514 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
 515 .TP
 516 .BR "\-\-syscall"
 517 System call event. Enabling syscalls tracing (kernel tracer), you will
 518 not be able to disable them with disable-event. This is a known
 519 limitation. You can disable the entire channel to do the trick.
 520 .TP
 521 .BR "\-\-filter 'expression'"
 522 Set a filter on a newly enabled event. Filter expression on event
 523 fields and context. Event recording depends on evaluation. Only
 524 specify on first activation of a given event within a session.
 525 Filter only allowed when enabling events within a session before
 526 tracing is started. If the filter fails to link with the event
 527 within the traced domain, the event will be discarded.
 528 Currently, filter is only implemented for the user-space tracer.
 529
 530 Expression examples:
 531
 532 .nf
 533   'intfield > 500 && intfield < 503'
 534   '(strfield == "test" || intfield != 10) && intfield > 33'
 535   'doublefield > 1.1 && intfield < 5.3'
 536 .fi
 537
 538 Wildcards are allowed at the end of strings:
 539   'seqfield1 == "te*"'
 540 In string literals, the escape character is a '\\'. Use '\\*' for
 541 the '*' character, and '\\\\' for the '\\' character. Wildcard
 542 match any sequence of characters, including an empty sub-string
 543 (match 0 or more characters).
 544
 545 Context information can be used for filtering. The examples below show
 546 usage of context filtering on process name (with a wildcard), process ID
 547 range, and unique thread ID for filtering.  The process and thread ID of
 548 running applications can be found under columns "PID" and "LWP" of the
 549 "ps -eLf" command.
 550
 551 .nf
 552   '$ctx.procname == "demo*"'
 553   '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
 554   '$ctx.vtid == 1234'
 555 .fi
 556
 557 .RE
 558 .PP
 559
 560 .PP
 561 \fBdisable-channel\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
 562 .RS
 563 Disable tracing channel
 564
 565 Disabling a channel makes all event(s) in that channel to stop tracing. You can
 566 enable it back by calling \fBlttng enable-channel NAME\fP again.
 567
 568 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 569 file.
 570
 571 .B OPTIONS:
 572
 573 .TP
 574 .BR "\-h, \-\-help"
 575 Show summary of possible options and commands.
 576 .TP
 577 .BR "\-\-list-options"
 578 Simple listing of options
 579 .TP
 580 .BR "\-s, \-\-session NAME"
 581 Apply on session name
 582 .TP
 583 .BR "\-k, \-\-kernel"
 584 Apply for the kernel tracer
 585 .TP
 586 .BR "\-u, \-\-userspace"
 587 Apply for the user-space tracer
 588 .RE
 589 .PP
 590
 591 .PP
 592 \fBdisable-event\fP NAME[,NAME2,...] (\-k | \-u) [OPTIONS]
 593 .RS
 594 Disable tracing event
 595
 596 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
 597 NAME\fP again.
 598
 599 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 600 file.
 601
 602 If \fB\-c, \-\-channel\fP is omitted, the default channel name is used.
 603 If \fB\-c, \-\-channel\fP is omitted, but a non-default channel already
 604 exists within the session, an error is returned.
 605
 606 .B OPTIONS:
 607
 608 .TP
 609 .BR "\-h, \-\-help"
 610 Show summary of possible options and commands.
 611 .TP
 612 .BR "\-\-list-options"
 613 Simple listing of options
 614 .TP
 615 .BR "\-s, \-\-session NAME"
 616 Apply on session name
 617 .TP
 618 .BR "\-c, \-\-channel NAME"
 619 Apply on channel name
 620 .TP
 621 .BR "\-a, \-\-all-events"
 622 Disable all events. This does NOT disable "*" but rather every known
 623 events of the session.
 624 .TP
 625 .BR "\-k, \-\-kernel"
 626 Apply for the kernel tracer
 627 .TP
 628 .BR "\-u, \-\-userspace"
 629 Apply for the user-space tracer
 630 .RE
 631 .PP
 632
 633 .PP
 634 \fBlist\fP [OPTIONS] [SESSION [SESSION OPTIONS]]
 635 .RS
 636 List tracing session information.
 637
 638 With no arguments, it will list available tracing session(s).
 639
 640 With the session name, it will display the details of the session including
 641 the trace file path, the associated channels and their state (activated
 642 and deactivated), the activated events and more.
 643
 644 With \-k alone, it will list all available kernel events (except the system
 645 calls events).
 646 With \-u alone, it will list all available user-space events from registered
 647 applications. Here is an example of 'lttng list \-u':
 648
 649 .nf
 650 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
 651       ust_tests_hello:tptest_sighandler (type: tracepoint)
 652       ust_tests_hello:tptest (type: tracepoint)
 653 .fi
 654
 655 You can now enable any event listed by using the name :
 656 \fBust_tests_hello:tptest\fP.
 657
 658 .B OPTIONS:
 659
 660 .TP
 661 .BR "\-h, \-\-help"
 662 Show summary of possible options and commands.
 663 .TP
 664 .BR "\-\-list-options"
 665 Simple listing of options
 666 .TP
 667 .BR "\-k, \-\-kernel"
 668 Select kernel domain
 669 .TP
 670 .BR "\-u, \-\-userspace"
 671 Select user-space domain.
 672
 673 .PP
 674 .B SESSION OPTIONS:
 675
 676 .TP
 677 .BR "\-c, \-\-channel NAME"
 678 List details of a channel
 679 .TP
 680 .BR "\-d, \-\-domain"
 681 List available domain(s)
 682 .RE
 683 .PP
 684
 685 .PP
 686 \fBset-session\fP NAME [OPTIONS]
 687 .RS
 688 Set current session name
 689
 690 Will change the session name in the .lttngrc file.
 691
 692 .B OPTIONS:
 693
 694 .TP
 695 .BR "\-h, \-\-help"
 696 Show summary of possible options and commands.
 697 .TP
 698 .BR "\-\-list-options"
 699 Simple listing of options
 700 .RE
 701 .PP
 702
 703 .PP
 704 \fBsnapshot\fP [OPTIONS] ACTION
 705 .RS
 706 Snapshot command for LTTng session.
 707
 708 .B OPTIONS:
 709
 710 .TP
 711 .BR "\-h, \-\-help"
 712 Show summary of possible options and commands.
 713 .TP
 714 .BR "\-\-list-options"
 715 Simple listing of options
 716
 717 .PP
 718 .B ACTION:
 719
 720 .TP
 721 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
 722
 723 Setup and add an snapshot output for a session. Output are the destination
 724 where the snapshot will be sent. Only one output is permitted. To change it,
 725 you'll need to delete it and add back the new one.
 726
 727 .TP
 728 \fBdel-output\fP ID | NAME [-s <NAME>]
 729
 730 Delete an output for a session using the ID. You can either specify the
 731 output's ID that can be found with list-output or the name.
 732
 733 .TP
 734 \fBlist-output\fP [-s <NAME>]
 735
 736 List the output of a session. Attributes of the output are printed.
 737
 738 .TP
 739 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
 740
 741 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
 742 used instead of a previously added output. Specifying only a name or/and a max
 743 size will override the current output values. For instance, you can record a
 744 snapshot with a custom maximum size or with a different name.
 745
 746 .nf
 747 $ lttng add-output -n mysnapshot file:///data/snapshot
 748 [...]
 749 $ lttng snapshot record -n new_name_snapshot
 750 .fi
 751
 752 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
 753 rather then in mysnapshot*/
 754
 755 .PP
 756 .B DETAILED ACTION OPTIONS
 757
 758 .TP
 759 .BR "\-s, \-\-session NAME"
 760 Apply to session name.
 761 .TP
 762 .BR "\-n, \-\-name NAME"
 763 Name of the snapshot's output.
 764 .TP
 765 .BR "\-m, \-\-max-size SIZE"
 766 Maximum size in bytes of the snapshot. The maxium size does not include
 767 the metadata file.
 768 .TP
 769 .BR "\-C, \-\-ctrl-url URL"
 770 Set control path URL. (Must use -D also)
 771 .TP
 772 .BR "\-D, \-\-data-url URL"
 773 Set data path URL. (Must use -C also)
 774 .RE
 775 .PP
 776
 777 .PP
 778 \fBstart\fP [NAME] [OPTIONS]
 779 .RS
 780 Start tracing
 781
 782 It will start tracing for all tracers for a specific tracing session.
 783 If NAME is omitted, the session name is taken from the .lttngrc file.
 784
 785 .B OPTIONS:
 786
 787 .TP
 788 .BR "\-h, \-\-help"
 789 Show summary of possible options and commands.
 790 .TP
 791 .BR "\-\-list-options"
 792 Simple listing of options
 793 .RE
 794 .PP
 795
 796 .PP
 797 \fBstop\fP [NAME] [OPTIONS]
 798 .RS
 799 Stop tracing
 800
 801 It will stop tracing for all tracers for a specific tracing session. Before
 802 returning, the command checks for data availability meaning that it will wait
 803 until the trace is readable for the session. Use \-\-no-wait to avoid this
 804 behavior.
 805
 806 If NAME is omitted, the session name is taken from the .lttngrc file.
 807
 808 .B OPTIONS:
 809
 810 .TP
 811 .BR "\-h, \-\-help"
 812 Show summary of possible options and commands.
 813 .TP
 814 .BR "\-\-list-options"
 815 Simple listing of options
 816 .TP "\-\-no-wait"
 817 Don't wait for data availability.
 818 .RE
 819 .PP
 820
 821 .PP
 822 \fBversion\fP
 823 .RS
 824 Show version information
 825
 826 .B OPTIONS:
 827
 828 .TP
 829 .BR "\-h, \-\-help"
 830 Show summary of possible options and commands.
 831 .TP
 832 .BR "\-\-list-options"
 833 Simple listing of options
 834 .RE
 835 .PP
 836
 837 .PP
 838 \fBview\fP [SESSION_NAME] [OPTIONS]
 839 .RS
 840 View traces of a tracing session.  By default, the babeltrace viewer
 841 will be used for text viewing.  If SESSION_NAME is omitted, the session
 842 name is taken from the .lttngrc file.
 843
 844 .B OPTIONS:
 845
 846 .TP
 847 .BR "\-h, \-\-help"
 848 Show this help
 849 .TP
 850 .BR "\-\-list-options"
 851 Simple listing of options
 852 .TP
 853 .BR "\-t, \-\-trace-path PATH"
 854 Trace directory path for the viewer
 855 .TP
 856 .BR "\-e, \-\-viewer CMD"
 857 Specify viewer and/or options to use This will completely override the
 858 default viewers so please make sure to specify the full command. The
 859 trace directory path of the session will be appended at the end to the
 860 arguments
 861 .RE
 862 .PP
 863
 864 .SH "EXIT VALUES"
 865 .PP
 866 On success 0 is returned and a positive value on error. Value of 1 means a command
 867 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
 868 something went wrong during the command.
 869
 870 Any other value above 10, please refer to
 871 .BR "<lttng/lttng-error.h>"
 872 for a detailed list or use lttng_strerror() to get a human readable string of
 873 the error code.
 874 .PP
 875
 876 .SH "ENVIRONMENT VARIABLES"
 877
 878 .PP
 879 Note that all command line options override environment variables.
 880 .PP
 881
 882 .PP
 883 .IP "LTTNG_SESSIOND_PATH"
 884 Allows one to specify the full session daemon binary path to lttng command line
 885 tool. You can also use \-\-sessiond-path option having the same effect.
 886 .PP
 887
 888 .SH "SEE ALSO"
 889 .BR babeltrace(1),
 890 .BR lttng-ust(3),
 891 .BR lttng-sessiond(8),
 892 .BR lttng-relayd(8),
 893 .BR lttng-health-check(3)
 894
 895 .SH "BUGS"
 896
 897 .PP
 898 If you encounter any issues or usability problem, please report it on our
 899 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
 900 at https://bugs.lttng.org which is a bugtracker.
 901 .PP
 902
 903 .SH "CREDITS"
 904
 905 .PP
 906 lttng is distributed under the GNU General Public License version 2. See the file
 907 COPYING for details.
 908 .PP
 909 A Web site is available at http://lttng.org for more information on the LTTng
 910 project.
 911 .PP
 912 You can also find our git tree at http://git.lttng.org.
 913 .PP
 914 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
 915 .PP
 916 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
 917 .PP
 918 .SH "THANKS"
 919
 920 .PP
 921 Thanks to Yannick Brosseau without whom this project would never have been so
 922 lean and mean! Also thanks to the Ericsson teams working on tracing which
 923 helped us greatly with detailed bug reports and unusual test cases.
 924
 925 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
 926 maintainer) and Jon Bernard for our Debian packages.
 927
 928 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
 929 Montreal for the LTTng journey.
 930 .PP
 931 .SH "AUTHORS"
 932
 933 .PP
 934 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
 935 David Goulet. More people have since contributed to it. It is currently
 936 maintained by David Goulet <dgoulet@efficios.com>.
 937 .PP