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 .IP "\fBenable-event\fP NAME[,NAME2,...] [-k|-u] [OPTIONS]"
 452 .nf
 453 Enable tracing event
 454
 455 A tracing event is always assigned to a channel. If \fB\-c, \-\-channel\fP is
 456 omitted, a default channel named '\fBchannel0\fP' is created and the event is
 457 added to it. For the user-space tracer, using \fB\-a, \-\-all\fP is the same as
 458 using the wildcard "*".
 459
 460 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 461 file.
 462 .fi
 463
 464 .B OPTIONS:
 465
 466 .nf
 467 \-h, \-\-help
 468         Show summary of possible options and commands.
 469 \-\-list-options
 470         Simple listing of options
 471 \-s, \-\-session NAME
 472         Apply on session name
 473 \-c, \-\-channel NAME
 474         Apply on channel name
 475 \-a, \-\-all
 476         Enable all tracepoints and syscalls. This actually enable a single
 477         wildcard event "*".
 478 \-k, \-\-kernel
 479         Apply for the kernel tracer
 480 \-u, \-\-userspace
 481         Apply for the user-space tracer
 482
 483 \-\-tracepoint
 484         Tracepoint event (default)
 485         - userspace tracer supports wildcards at end of string. Don't forget to
 486         quote to deal with bash expansion.
 487         e.g.:
 488         "*"
 489         "app_component:na*"
 490 \-\-loglevel NAME
 491         Tracepoint loglevel range from 0 to loglevel. Listed in the help (\-h).
 492 \-\-loglevel-only NAME
 493         Tracepoint loglevel (only this loglevel).
 494
 495         The loglevel or loglevel-only options should be combined with a
 496         tracepoint name or tracepoint wildcard.
 497 \-\-probe [addr | symbol | symbol+offset]
 498         Dynamic probe. Addr and offset can be octal (0NNN...), decimal (NNN...)
 499         or hexadecimal (0xNNN...)
 500 \-\-function [addr | symbol | symbol+offset]
 501         Dynamic function entry/return probe. Addr and offset can be octal
 502         (0NNN...), decimal (NNN...) or hexadecimal (0xNNN...)
 503 \-\-syscall
 504         System call event. Enabling syscalls tracing (kernel tracer), you will
 505         not be able to disable them with disable-event. This is a known
 506         limitation. You can disable the entire channel to do the trick.
 507
 508 \-\-filter 'expression'
 509         Set a filter on a newly enabled event. Filter expression on event
 510         fields and context. Event recording depends on evaluation. Only
 511         specify on first activation of a given event within a session.
 512         Filter only allowed when enabling events within a session before
 513         tracing is started. If the filter fails to link with the event
 514         within the traced domain, the event will be discarded.
 515         Currently, filter is only implemented for the user-space tracer.
 516
 517         Expression examples:
 518
 519         'intfield > 500 && intfield < 503'
 520         '(stringfield == "test" || intfield != 10) && intfield > 33'
 521         'doublefield > 1.1 && intfield < 5.3'
 522
 523         Wildcards are allowed at the end of strings:
 524         'seqfield1 == "te*"'
 525         In string literals, the escape character is a '\\'. Use '\\*' for
 526         the '*' character, and '\\\\' for the '\\' character. Wildcard
 527         match any sequence of characters, including an empty sub-string
 528         (match 0 or more characters).
 529
 530         Context information can be used for filtering. The examples
 531         below show usage of context filtering on process name (with a
 532         wildcard), process ID range, and unique thread ID for filtering.
 533         The process and thread ID of running applications can be found
 534         under columns "PID" and "LWP" of the "ps -eLf" command.
 535
 536         '$ctx.procname == "demo*"'
 537         '$ctx.vpid >= 4433 && $ctx.vpid < 4455'
 538         '$ctx.vtid == 1234'
 539 .fi
 540
 541 .IP "\fBdisable-channel\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"
 542 .nf
 543 Disable tracing channel
 544
 545 Disabling a channel makes all event(s) in that channel to stop tracing. You can
 546 enable it back by calling \fBlttng enable-channel NAME\fP again.
 547
 548 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 549 file.
 550 .fi
 551
 552 .B OPTIONS:
 553
 554 .nf
 555 \-h, \-\-help
 556         Show summary of possible options and commands.
 557 \-\-list-options
 558         Simple listing of options
 559 \-s, \-\-session NAME
 560         Apply on session name
 561 \-k, \-\-kernel
 562         Apply for the kernel tracer
 563 \-u, \-\-userspace
 564         Apply for the user-space tracer
 565 .fi
 566
 567 .IP "\fBdisable-event\fP NAME[,NAME2,...] [\-k|\-u] [OPTIONS]"
 568 .nf
 569 Disable tracing event
 570
 571 The event, once disabled, can be re-enabled by calling \fBlttng enable-event
 572 NAME\fP again.
 573
 574 If \fB\-s, \-\-session\fP is omitted, the session name is taken from the .lttngrc
 575 file.
 576 .fi
 577
 578 .B OPTIONS:
 579
 580 .nf
 581 \-h, \-\-help
 582         Show summary of possible options and commands.
 583 \-\-list-options
 584         Simple listing of options
 585 \-s, \-\-session NAME
 586         Apply on session name
 587 \-a, \-\-all-events
 588         Disable all events. This does NOT disable "*" but rather
 589         every known events of the session.
 590 \-k, \-\-kernel
 591         Apply for the kernel tracer
 592 \-u, \-\-userspace
 593         Apply for the user-space tracer
 594 .fi
 595
 596 .IP "\fBlist\fP [\-k|\-u] [SESSION [SESSION_OPTIONS]]"
 597 .nf
 598 List tracing session information.
 599
 600 With no arguments, it will list available tracing session(s).
 601
 602 With the session name, it will display the details of the session including
 603 the trace file path, the associated channels and their state (activated
 604 and deactivated), the activated events and more.
 605
 606 With \-k alone, it will list all available kernel events (except the system
 607 calls events).
 608 With \-u alone, it will list all available user-space events from registered
 609 applications. Here is an example of 'lttng list \-u':
 610
 611 PID: 7448 - Name: /tmp/lttng-ust/tests/hello/.libs/lt-hello
 612       ust_tests_hello:tptest_sighandler (type: tracepoint)
 613       ust_tests_hello:tptest (type: tracepoint)
 614
 615 You can now enable any event listed by using the name :
 616 \fBust_tests_hello:tptest\fP.
 617 .fi
 618
 619 .B OPTIONS:
 620
 621 .nf
 622 \-h, \-\-help
 623         Show summary of possible options and commands.
 624 \-\-list-options
 625         Simple listing of options
 626 \-k, \-\-kernel
 627         Select kernel domain
 628 \-u, \-\-userspace
 629         Select user-space domain.
 630
 631 .B SESSION OPTIONS:
 632
 633 \-c, \-\-channel NAME
 634         List details of a channel
 635 \-d, \-\-domain
 636         List available domain(s)
 637 .fi
 638
 639 .IP "\fBset-session\fP NAME"
 640 .nf
 641 Set current session name
 642
 643 Will change the session name in the .lttngrc file.
 644 .fi
 645
 646 .B OPTIONS:
 647
 648 .nf
 649 \-h, \-\-help
 650         Show summary of possible options and commands.
 651 \-\-list-options
 652         Simple listing of options
 653 .fi
 654
 655 .IP
 656
 657 .IP "\fBsnapshot\fP ACTION"
 658 .nf
 659 Snapshot command for LTTng session.
 660 .fi
 661
 662 .B OPTIONS:
 663
 664 .nf
 665 \-h, \-\-help
 666         Show summary of possible options and commands.
 667 \-\-list-options
 668         Simple listing of options
 669 .fi
 670
 671 .B ACTION:
 672
 673 .nf
 674 \fBadd-output\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] <URL> | -C <URL> -D <URL>
 675
 676 Setup and add an snapshot output for a session. Output are the destination
 677 where the snapshot will be sent. Only one output is permitted. To change it,
 678 you'll need to delete it and add back the new one.
 679
 680 \fBdel-output\fP ID | NAME [-s <NAME>]
 681
 682 Delete an output for a session using the ID. You can either specify the
 683 output's ID that can be found with list-output or the name.
 684
 685 \fBlist-output\fP [-s <NAME>]
 686
 687 List the output of a session. Attributes of the output are printed.
 688
 689 \fBrecord\fP [-m <SIZE>] [-s <NAME>] [-n <NAME>] [<URL> | -C <URL> -D <URL>]
 690
 691 Snapshot a session's buffer(s) for all domains. If an URL is specified, it is
 692 used instead of a previously added output. Specifying only a name or/and a max
 693 size will override the current output values. For instance, you can record a
 694 snapshot with a custom maximum size or with a different name.
 695
 696 $ lttng add-output -n mysnapshot file:///data/snapshot
 697 [...]
 698 $ lttng snapshot record -n new_name_snapshot
 699
 700 The above will create a snapshot in /data/snapshot/new_name_snapshot* directory
 701 rather then in mysnapshot*/
 702 .fi
 703
 704 .B LONG OPTIONS
 705
 706 .nf
 707 \-s, \-\-session NAME
 708         Apply to session name.
 709 \-n, \-\-name NAME
 710         Name of the snapshot's output.
 711 \-m, \-\-max-size SIZE
 712         Maximum size in bytes of the snapshot. The maxium size does not
 713         include the metadata file.
 714 \-C, \-\-ctrl-url URL
 715         Set control path URL. (Must use -D also)
 716 \-D, \-\-data-url URL
 717         Set data path URL. (Must use -C also)
 718 .fi
 719
 720 .IP
 721
 722 .IP "\fBstart\fP [NAME] [OPTIONS]"
 723 .nf
 724 Start tracing
 725
 726 It will start tracing for all tracers for a specific tracing session.
 727
 728 If NAME is omitted, the session name is taken from the .lttngrc file.
 729 .fi
 730
 731 .B OPTIONS:
 732
 733 .nf
 734 \-h, \-\-help
 735         Show summary of possible options and commands.
 736 \-\-list-options
 737         Simple listing of options
 738 .fi
 739
 740 .IP
 741
 742 .IP "\fBstop\fP [NAME] [OPTIONS]"
 743 .nf
 744 Stop tracing
 745
 746 It will stop tracing for all tracers for a specific tracing session. Before
 747 returning, the command checks for data availability meaning that it will wait
 748 until the trace is readable for the session. Use \-\-no-wait to avoid this
 749 behavior.
 750
 751 If NAME is omitted, the session name is taken from the .lttngrc file.
 752 .fi
 753
 754 .B OPTIONS:
 755
 756 .nf
 757 \-h, \-\-help
 758         Show summary of possible options and commands.
 759 \-\-list-options
 760         Simple listing of options
 761 \-\-no-wait
 762         Don't wait for data availability.
 763 .fi
 764
 765 .IP
 766
 767 .IP "\fBversion\fP"
 768 .nf
 769 Show version information
 770 .fi
 771
 772 .B OPTIONS:
 773
 774 .nf
 775 \-h, \-\-help
 776         Show summary of possible options and commands.
 777 \-\-list-options
 778         Simple listing of options
 779 .fi
 780
 781 .IP
 782
 783 .IP "\fBview\fP [SESSION_NAME] [OPTIONS]"
 784 .nf
 785 View traces of a tracing session
 786
 787 By default, the babeltrace viewer will be used for text viewing.
 788
 789 If SESSION_NAME is omitted, the session name is taken from the .lttngrc file.
 790
 791 .fi
 792
 793 .B OPTIONS:
 794
 795 .nf
 796 \-h, \-\-help
 797         Show this help
 798 \-\-list-options
 799         Simple listing of options
 800 \-t, \-\-trace-path PATH
 801         Trace directory path for the viewer
 802 \-e, \-\-viewer CMD
 803         Specify viewer and/or options to use
 804         This will completely override the default viewers so
 805         please make sure to specify the full command. The trace
 806         directory path of the session will be appended at the end
 807         to the arguments
 808 .fi
 809
 810 .SH "EXIT VALUES"
 811 On success 0 is returned and a positive value on error. Value of 1 means a command
 812 error, 2 an undefined command, 3 a fatal error and 4 a command warning meaning that
 813 something went wrong during the command.
 814
 815 Any other value above 10, please refer to
 816 .BR <lttng/lttng-error.h>
 817 for a detailed list or use lttng_strerror() to get a human readable string of
 818 the error code.
 819
 820 .PP
 821 .SH "ENVIRONMENT VARIABLES"
 822
 823 .PP
 824 Note that all command line options override environment variables.
 825 .PP
 826
 827 .PP
 828 .IP "LTTNG_SESSIOND_PATH"
 829 Allows one to specify the full session daemon binary path to lttng command line
 830 tool. You can also use \-\-sessiond-path option having the same effect.
 831 .SH "SEE ALSO"
 832 .BR babeltrace(1),
 833 .BR lttng-ust(3),
 834 .BR lttng-sessiond(8),
 835 .BR lttng-relayd(8),
 836 .BR lttng-health-check(3)
 837 .SH "BUGS"
 838
 839 If you encounter any issues or usability problem, please report it on our
 840 mailing list <lttng-dev@lists.lttng.org> to help improve this project or
 841 at https://bugs.lttng.org which is a bugtracker.
 842 .SH "CREDITS"
 843
 844 .PP
 845 lttng is distributed under the GNU General Public License version 2. See the file
 846 COPYING for details.
 847 .PP
 848 A Web site is available at http://lttng.org for more information on the LTTng
 849 project.
 850 .PP
 851 You can also find our git tree at http://git.lttng.org.
 852 .PP
 853 Mailing lists for support and development: <lttng-dev@lists.lttng.org>.
 854 .PP
 855 You can find us on IRC server irc.oftc.net (OFTC) in #lttng.
 856 .PP
 857 .SH "THANKS"
 858
 859 .PP
 860 Thanks to Yannick Brosseau without whom this project would never have been so
 861 lean and mean! Also thanks to the Ericsson teams working on tracing which
 862 helped us greatly with detailed bug reports and unusual test cases.
 863
 864 Thanks to our beloved packager Alexandre Montplaisir-Goncalves (Ubuntu and PPA
 865 maintainer) and Jon Bernard for our Debian packages.
 866
 867 Special thanks to Michel Dagenais and the DORSAL laboratory at Polytechnique de
 868 Montreal for the LTTng journey.
 869 .PP
 870 .SH "AUTHORS"
 871
 872 .PP
 873 lttng-tools was originally written by Mathieu Desnoyers, Julien Desfossez and
 874 David Goulet. More people have since contributed to it. It is currently
 875 maintained by David Goulet <dgoulet@efficios.com>.
 876 .PP