doc/man/lttng.1

   1 .TH "LTTNG" "1" "December 3rd, 2012" "" ""
   2
   3 .SH "NAME"
   4 lttng \(em LTTng 2.x tracer control command line tool
   5
   6 .SH "SYNOPSIS"
   7
   8 .PP
   9 .nf
  10 lttng [OPTIONS] <COMMAND>
  11 .fi
  12 .SH "DESCRIPTION"
  13
  14 .PP
  15 The LTTng project aims at providing highly efficient tracing tools for Linux.
  16 It's tracers help tracking down performance issues and debugging problems
  17 involving multiple concurrent processes and threads. Tracing across multiple
  18 systems is also possible.
  19
  20 The \fBlttng\fP command line tool from the lttng-tools package is used to control
  21 both kernel and user-space tracing. Every interactions with the tracer should
  22 be done by this tool or by the liblttng-ctl provided with the lttng-tools
  23 package.
  24
  25 LTTng uses a session daemon (lttng-sessiond(8)), acting as a tracing registry,
  26 which allows you to interact with multiple tracers (kernel and user-space)
  27 inside the same container, a tracing session. Traces can be gathered from the
  28 kernel and/or instrumented applications (lttng-ust(3)). Aggregating and reading
  29 those traces is done using the babeltrace(1) text viewer.
  30
  31 We introduce the notion of \fBtracing domains\fP which is essentially a type of
  32 tracer (kernel or user space for now). In the future, we could see a third
  33 tracer being for instance an hypervisor. For some commands, you'll need to
  34 specify on which domain the command applies (-u or -k). For instance, enabling
  35 a kernel event, you must specify the kernel domain to the command so we know
  36 for which tracer this event is for.
  37
  38 In order to trace the kernel, the session daemon needs to be running as root.
  39 LTTng provides the use of a \fBtracing group\fP (default: tracing). Whomever is
  40 in that group can interact with the root session daemon and thus trace the
  41 kernel. Session daemons can co-exist meaning that you can have a session daemon
  42 running as Alice that can be used to trace her applications along side with a
  43 root daemon or even a Bob daemon. We highly recommend to start the session
  44 daemon at boot time for stable and long term tracing.
  45
  46 Every user-space applications instrumented with lttng-ust(3), will
  47 automatically register to the session daemon. This feature gives you the
  48 ability to list available traceable applications and tracepoints on a per user
  49 basis. (See \fBlist\fP command).
  50 .SH "OPTIONS"
  51
  52 .PP
  53 This program follow the usual GNU command line syntax with long options starting with
  54 two dashes. Below is a summary of the available options.
  55 .PP
  56
  57 .TP
  58 .BR "\-h, \-\-help"
  59 Show summary of possible options and commands.
  60 .TP
  61 .BR "\-v, \-\-verbose"
  62 Increase verbosity.
  63 Three levels of verbosity are available which are triggered by putting additional v to
  64 the option (\-vv or \-vvv)
  65 .TP
  66 .BR "\-q, \-\-quiet"
  67 Suppress all messages (even errors).
  68 .TP
  69 .BR "\-g, \-\-group NAME"
  70 Set unix tracing group name. (default: tracing)
  71 .TP
  72 .BR "\-n, \-\-no-sessiond"
  73 Don't automatically spawn a session daemon.
  74 .TP
  75 .BR "\-\-sessiond\-path PATH"
  76 Set session daemon full binary path.
  77 .TP
  78 .BR "\-\-list\-options"
  79 Simple listing of lttng options.
  80 .TP
  81 .BR "\-\-list\-commands"
  82 Simple listing of lttng commands.
  83 .SH "COMMANDS"
  84
  85 .PP
  86 \fBadd-context\fP [OPTIONS]
  87 .RS
  88 Add context to event(s) and/or channel(s).
  89
  90 A context is basically extra information appended to a channel. For instance,
  91 you could ask the tracer to add the PID information for all events in a
  92 channel. You can also add performance monitoring unit counters (perf PMU) using
  93 the perf kernel API).
  94
  95 For example, this command will add the context information 'prio' and two perf
  96 counters (hardware branch misses and cache misses), to all events in the trace
  97 data output:
  98
  99 .nf
 100 # lttng add-context \-k \-t prio \-t perf:branch-misses \\
 101                 \-t perf:cache-misses
 102 .fi
 103
 104 Please take a look at the help (\-h/\-\-help) for a detailed list of available
 105 contexts.
 106
 107 If no channel is given (\-c), the context is added to all channels that were
 108 already enabled. If the session has no channel, a default channel is created.
 109 Otherwise the context 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. For the user-space tracer, using \fB\-a, \-\-all\fP is the same as
 459 using the wildcard "*".
 460
 461 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 462 file.
 463
 464 .B OPTIONS:
 465
 466 .TP
 467 .BR "\-h, \-\-help"
 468 Show summary of possible options and commands.
 469 .TP
 470 .BR "\-\-list-options"
 471 Simple listing of options
 472 .TP
 473 .BR "\-s, \-\-session NAME"
 474 Apply on session name
 475 .TP
 476 .BR "\-c, \-\-channel NAME"
 477 Apply on channel name
 478 .TP
 479 .BR "\-a, \-\-all"
 480 Enable all tracepoints and syscalls. This actually enable a single
 481 wildcard event "*".
 482 .TP
 483 .BR "\-k, \-\-kernel"
 484 Apply for the kernel tracer
 485 .TP
 486 .BR "\-u, \-\-userspace"
 487 Apply for the user-space tracer
 488 .TP
 489 .BR "\-\-tracepoint"
 490 Tracepoint event (default). Userspace tracer supports wildcards at end
 491 of string. Don't forget to quote to deal with bash expansion.
 492 e.g.:
 493 .nf
 494         "*"
 495         "app_component:na*"
 496 .fi
 497 .TP
 498 .BR "\-\-loglevel NAME"
 499 Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
 500 .TP
 501 .BR "\-\-loglevel-only NAME"
 502 Tracepoint loglevel (only this loglevel).
 503 The loglevel or loglevel-only options should be combined with a
 504 tracepoint name or tracepoint wildcard.
 505 .TP
 506 .BR "\-\-probe (addr | symbol | symbol+offset)"
 507 Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
 508 or hexadecimal (0xNNN...)
 509 .TP
 510 .BR "\-\-function (addr | symbol | symbol+offset)"
 511 Dynamic function entry/return probe. Addr and offset can be octal
 512 (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
 513 .TP
 514 .BR "\-\-syscall"
 515 System call event. Enabling syscalls tracing (kernel tracer), you will
 516 not be able to disable them with disable-event. This is a known
 517 limitation. You can disable the entire channel to do the trick.
 518 .TP
 519 .BR "\-\-filter 'expression'"
 520 Set a filter on a newly enabled event. Filter expression on event
 521 fields and context. Event recording depends on evaluation. Only
 522 specify on first activation of a given event within a session.
 523 Filter only allowed when enabling events within a session before
 524 tracing is started. If the filter fails to link with the event
 525 within the traced domain, the event will be discarded.
 526 Currently, filter is only implemented for the user-space tracer.
 527
 528 Expression examples:
 529
 530 .nf
 531   'intfield > 500 && intfield < 503'
 532   '(strfield == "test" || intfield != 10) && intfield > 33'
 533   'doublefield > 1.1 && intfield < 5.3'
 534 .fi
 535
 536 Wildcards are allowed at the end of strings:
 537   'seqfield1 == "te*"'
 538 In string literals, the escape character is a '\\'. Use '\\*' for
 539 the '*' character, and '\\\\' for the '\\' character. Wildcard
 540 match any sequence of characters, including an empty sub-string
 541 (match 0 or more characters).
 542
 543 Context information can be used for filtering. The examples below show
 544 usage of context filtering on process name (with a wildcard), process ID
 545 range, and unique thread ID for filtering.  The process and thread ID of
 546 running applications can be found under columns "PID" and "LWP" of the
 547 "ps -eLf" command.
 548
 549 .nf
 550   '$ctx.procname == "demo*"'
 551   '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
 552   '$ctx.vtid == 1234'
 553 .fi
 554
 555 .RE
 556 .PP
 557
 558 .IP "\fBdisable-channel\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"
 559 .nf
 560 Disable tracing channel
 561
 562 Disabling a channel makes all event(s) in that channel to stop tracing. You can
 563 enable it back by calling \fBlttng enable-channel NAME\fP again.
 564
 565 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 566 file.
 567 .fi
 568
 569 .B OPTIONS:
 570
 571 .nf
 572 \-h, \-\-help
 573         Show summary of possible options and commands.
 574 \-\-list-options
 575         Simple listing of options
 576 \-s, \-\-session NAME
 577         Apply on session name
 578 \-k, \-\-kernel
 579         Apply for the kernel tracer
 580 \-u, \-\-userspace
 581         Apply for the user-space tracer
 582 .fi
 583
 584 .IP "\fBdisable-event\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"
 585 .nf
 586 Disable tracing event
 587
 588 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
 589 NAME\fP again.
 590
 591 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 592 file.
 593 .fi
 594
 595 .B OPTIONS:
 596
 597 .nf
 598 \-h, \-\-help
 599         Show summary of possible options and commands.
 600 \-\-list-options
 601         Simple listing of options
 602 \-s, \-\-session NAME
 603         Apply on session name
 604 \-a, \-\-all-events
 605         Disable all events. This does NOT disable "*" but rather
 606         every known events of the session.
 607 \-k, \-\-kernel
 608         Apply for the kernel tracer
 609 \-u, \-\-userspace
 610         Apply for the user-space tracer
 611 .fi
 612
 613 .IP "\fBlist\fP [\-k|\-u] [SESSION [SESSION_OPTIONS]]"
 614 .nf
 615 List tracing session information.
 616
 617 With no arguments, it will list available tracing session(s).
 618
 619 With the session name, it will display the details of the session including
 620 the trace file path, the associated channels and their state (activated
 621 and deactivated), the activated events and more.
 622
 623 With \-k alone, it will list all available kernel events (except the system
 624 calls events).
 625 With \-u alone, it will list all available user-space events from registered
 626 applications. Here is an example of 'lttng list \-u':
 627
 628 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
 629       ust_tests_hello:tptest_sighandler (type: tracepoint)
 630       ust_tests_hello:tptest (type: tracepoint)
 631
 632 You can now enable any event listed by using the name :
 633 \fBust_tests_hello:tptest\fP.
 634 .fi
 635
 636 .B OPTIONS:
 637
 638 .nf
 639 \-h, \-\-help
 640         Show summary of possible options and commands.
 641 \-\-list-options
 642         Simple listing of options
 643 \-k, \-\-kernel
 644         Select kernel domain
 645 \-u, \-\-userspace
 646         Select user-space domain.
 647
 648 .B SESSION OPTIONS:
 649
 650 \-c, \-\-channel NAME
 651         List details of a channel
 652 \-d, \-\-domain
 653         List available domain(s)
 654 .fi
 655
 656 .IP "\fBset-session\fP NAME"
 657 .nf
 658 Set current session name
 659
 660 Will change the session name in the .lttngrc file.
 661 .fi
 662
 663 .B OPTIONS:
 664
 665 .nf
 666 \-h, \-\-help
 667         Show summary of possible options and commands.
 668 \-\-list-options
 669         Simple listing of options
 670 .fi
 671
 672 .IP
 673
 674 .IP "\fBsnapshot\fP ACTION"
 675 .nf
 676 Snapshot command for LTTng session.
 677 .fi
 678
 679 .B OPTIONS:
 680
 681 .nf
 682 \-h, \-\-help
 683         Show summary of possible options and commands.
 684 \-\-list-options
 685         Simple listing of options
 686 .fi
 687
 688 .B ACTION:
 689
 690 .nf
 691 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
 692
 693 Setup and add an snapshot output for a session. Output are the destination
 694 where the snapshot will be sent. Only one output is permitted. To change it,
 695 you'll need to delete it and add back the new one.
 696
 697 \fBdel-output\fP ID | NAME [-s <NAME>]
 698
 699 Delete an output for a session using the ID. You can either specify the
 700 output's ID that can be found with list-output or the name.
 701
 702 \fBlist-output\fP [-s <NAME>]
 703
 704 List the output of a session. Attributes of the output are printed.
 705
 706 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
 707
 708 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
 709 used instead of a previously added output. Specifying only a name or/and a max
 710 size will override the current output values. For instance, you can record a
 711 snapshot with a custom maximum size or with a different name.
 712
 713 $ lttng add-output -n mysnapshot file:///data/snapshot
 714 [...]
 715 $ lttng snapshot record -n new_name_snapshot
 716
 717 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
 718 rather then in mysnapshot*/
 719 .fi
 720
 721 .B LONG OPTIONS
 722
 723 .nf
 724 \-s, \-\-session NAME
 725         Apply to session name.
 726 \-n, \-\-name NAME
 727         Name of the snapshot's output.
 728 \-m, \-\-max-size SIZE
 729         Maximum size in bytes of the snapshot. The maxium size does not
 730         include the metadata file.
 731 \-C, \-\-ctrl-url URL
 732         Set control path URL. (Must use -D also)
 733 \-D, \-\-data-url URL
 734         Set data path URL. (Must use -C also)
 735 .fi
 736
 737 .IP
 738
 739 .IP "\fBstart\fP [NAME] [OPTIONS]"
 740 .nf
 741 Start tracing
 742
 743 It will start tracing for all tracers for a specific tracing session.
 744
 745 If NAME is omitted, the session name is taken from the .lttngrc file.
 746 .fi
 747
 748 .B OPTIONS:
 749
 750 .nf
 751 \-h, \-\-help
 752         Show summary of possible options and commands.
 753 \-\-list-options
 754         Simple listing of options
 755 .fi
 756
 757 .IP
 758
 759 .IP "\fBstop\fP [NAME] [OPTIONS]"
 760 .nf
 761 Stop tracing
 762
 763 It will stop tracing for all tracers for a specific tracing session. Before
 764 returning, the command checks for data availability meaning that it will wait
 765 until the trace is readable for the session. Use \-\-no-wait to avoid this
 766 behavior.
 767
 768 If NAME is omitted, the session name is taken from the .lttngrc file.
 769 .fi
 770
 771 .B OPTIONS:
 772
 773 .nf
 774 \-h, \-\-help
 775         Show summary of possible options and commands.
 776 \-\-list-options
 777         Simple listing of options
 778 \-\-no-wait
 779         Don't wait for data availability.
 780 .fi
 781
 782 .IP
 783
 784 .IP "\fBversion\fP"
 785 .nf
 786 Show version information
 787 .fi
 788
 789 .B OPTIONS:
 790
 791 .nf
 792 \-h, \-\-help
 793         Show summary of possible options and commands.
 794 \-\-list-options
 795         Simple listing of options
 796 .fi
 797
 798 .IP
 799
 800 .IP "\fBview\fP [SESSION_NAME] [OPTIONS]"
 801 .nf
 802 View traces of a tracing session
 803
 804 By default, the babeltrace viewer will be used for text viewing.
 805
 806 If SESSION_NAME is omitted, the session name is taken from the .lttngrc file.
 807
 808 .fi
 809
 810 .B OPTIONS:
 811
 812 .nf
 813 \-h, \-\-help
 814         Show this help
 815 \-\-list-options
 816         Simple listing of options
 817 \-t, \-\-trace-path PATH
 818         Trace directory path for the viewer
 819 \-e, \-\-viewer CMD
 820         Specify viewer and/or options to use
 821         This will completely override the default viewers so
 822         please make sure to specify the full command. The trace
 823         directory path of the session will be appended at the end
 824         to the arguments
 825 .fi
 826
 827 .SH "EXIT VALUES"
 828 On success 0 is returned and a positive value on error. Value of 1 means a command
 829 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
 830 something went wrong during the command.
 831
 832 Any other value above 10, please refer to
 833 .BR <lttng/lttng-error.h>
 834 for a detailed list or use lttng_strerror() to get a human readable string of
 835 the error code.
 836
 837 .PP
 838 .SH "ENVIRONMENT VARIABLES"
 839
 840 .PP
 841 Note that all command line options override environment variables.
 842 .PP
 843
 844 .PP
 845 .IP "LTTNG_SESSIOND_PATH"
 846 Allows one to specify the full session daemon binary path to lttng command line
 847 tool. You can also use \-\-sessiond-path option having the same effect.
 848 .SH "SEE ALSO"
 849 .BR babeltrace(1),
 850 .BR lttng-ust(3),
 851 .BR lttng-sessiond(8),
 852 .BR lttng-relayd(8),
 853 .BR lttng-health-check(3)
 854 .SH "BUGS"
 855
 856 If you encounter any issues or usability problem, please report it on our
 857 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
 858 at https://bugs.lttng.org which is a bugtracker.
 859 .SH "CREDITS"
 860
 861 .PP
 862 lttng is distributed under the GNU General Public License version 2. See the file
 863 COPYING for details.
 864 .PP
 865 A Web site is available at http://lttng.org for more information on the LTTng
 866 project.
 867 .PP
 868 You can also find our git tree at http://git.lttng.org.
 869 .PP
 870 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
 871 .PP
 872 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
 873 .PP
 874 .SH "THANKS"
 875
 876 .PP
 877 Thanks to Yannick Brosseau without whom this project would never have been so
 878 lean and mean! Also thanks to the Ericsson teams working on tracing which
 879 helped us greatly with detailed bug reports and unusual test cases.
 880
 881 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
 882 maintainer) and Jon Bernard for our Debian packages.
 883
 884 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
 885 Montreal for the LTTng journey.
 886 .PP
 887 .SH "AUTHORS"
 888
 889 .PP
 890 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
 891 David Goulet. More people have since contributed to it. It is currently
 892 maintained by David Goulet <dgoulet@efficios.com>.
 893 .PP