doc/man/lttng.1.txt

   1 lttng(1)
   2 ========
   3
   4
   5 NAME
   6 ----
   7 lttng - LTTng 2 tracer control command-line tool
   8
   9
  10 SYNOPSIS
  11 --------
  12 [verse]
  13 *lttng* [option:--group='GROUP'] [option:--mi='TYPE'] [option:--no-sessiond | option:--sessiond-path='PATH']
  14       [option:--quiet | option:-v | option:-vv | option:-vvv] '<<commands,COMMAND>>' ['COMMAND OPTIONS']
  15
  16
  17 DESCRIPTION
  18 -----------
  19 The http://lttng.org/[_Linux Trace Toolkit: next generation_] is an open
  20 source software package used for correlated tracing of the Linux kernel,
  21 user applications, and user libraries.
  22
  23 LTTng consists of Linux kernel modules (for Linux kernel tracing) and
  24 dynamically loaded libraries (for user application and library tracing).
  25
  26 An LTTng _session daemon_, linklttng:lttng-sessiond(8), receives
  27 commands from the command-line interface `lttng` to control the LTTng
  28 tracers. All interactions with the LTTng tracers happen through the
  29 `lttng` tool or through the liblttng-ctl library shipped with the
  30 LTTng-tools package.
  31
  32 A _tracing domain_ is a tracer category. There are five available
  33 domains. For some commands, the domain needs to be specified with a
  34 command-line option. The domain options are:
  35
  36 nloption:-j, nloption:--jul::
  37     Apply command to the `java.util.logging` (JUL) domain.
  38
  39 nloption:-k, nloption:--kernel::
  40     Apply command to the Linux kernel domain.
  41
  42 nloption:-l, nloption:--log4j::
  43     Apply command to the https://logging.apache.org/log4j/1.2/[Apache log4j 1.2]
  44     (Java) domain.
  45
  46 nloption:-p, nloption:--python::
  47     Apply command to the https://www.python.org/[Python] domain.
  48
  49 nloption:-u, nloption:--userspace::
  50     Apply command to the user space domain (application using
  51     liblttng-ust directly; see linklttng:lttng-ust(3)).
  52
  53 The LTTng session daemon is a tracing registry which allows the user to
  54 interact with multiple tracers (kernel and user space) within the same
  55 container, a _tracing session_. Traces can be gathered from the Linux
  56 kernel and/or from instrumented applications (see
  57 linklttng:lttng-ust(3)). You can aggregate and read the events of LTTng
  58 traces using linklttng:babeltrace(1).
  59
  60 To trace the Linux kernel, the session daemon needs to be running as
  61 `root`. LTTng uses a _tracing group_ to allow specific users to interact
  62 with the root session daemon. The default tracing group name is
  63 `tracing`. You can use the option:--group option to set the tracing
  64 group name to use.
  65
  66 Session daemons can coexist. You can have a session daemon running as
  67 user Alice that can be used to trace her applications alongside a root
  68 session daemon or a session daemon running as user Bob.
  69
  70 NOTE: It is highly recommended to start the session daemon at boot time
  71 for stable and long-term tracing.
  72
  73 User applications instrumented with LTTng automatically register to the
  74 root session daemon and to user session daemons. This allows any session
  75 daemon to list the available traceable applications and event sources
  76 (see linklttng:lttng-list(1)).
  77
  78 By default, the linklttng:lttng-create(1) command automatically spawns a
  79 user session daemon if none is currently running. The
  80 option:--no-sessiond general option can be set to avoid this.
  81
  82
  83 OPTIONS
  84 -------
  85 option:-g, option:--group='GROUP'::
  86     Use 'GROUP' as Unix tracing group (default: `tracing`).
  87
  88 option:-m, option:--mi='TYPE'::
  89     Print the command's result using the machine interface type 'TYPE'
  90     instead of a human-readable output.
  91 +
  92 Supported types: `xml`.
  93 +
  94 The machine interface (MI) mode converts the traditional pretty-printing
  95 to a machine output syntax. The MI mode provides a change-resistant way
  96 to access information generated by the `lttng` command-line program.
  97 +
  98 When using the MI mode, the data is printed to the standard output.
  99 Errors and warnings are printed on the standard error with the
 100 pretty-print default format.
 101 +
 102 If any error occurs during the execution of a command, the return value
 103 of the command will be different than 0. In this case, `lttng` does
 104 :not: guarantee the syntax and data validity of the generated MI output.
 105 +
 106 For the `xml` MI type, an XML schema definition (XSD) file used for
 107 validation is available: see the `src/common/mi_lttng.xsd` file in
 108 the LTTng-tools source tree.
 109
 110 option:-n, option:--no-sessiond::
 111     Do not automatically spawn a session daemon.
 112
 113 option:-q, option:--quiet::
 114     Suppress all messages, including warnings and errors.
 115
 116 option:--sessiond-path='PATH'::
 117     Set the session daemon binary's absolute path to 'PATH'.
 118
 119 option:-v, option:--verbose::
 120     Increase verbosity.
 121 +
 122 Three levels of verbosity are available, which are triggered by
 123 appending additional `v` letters to the option
 124 (that is, `-vv` and `-vvv`).
 125
 126
 127 Program information
 128 ~~~~~~~~~~~~~~~~~~~
 129 option:-h, option:--help::
 130     Show help.
 131
 132 option:--list-commands::
 133     List available commands.
 134
 135 option:--list-options::
 136     List available general options.
 137
 138 option:-V, option:--version::
 139     Show version.
 140
 141
 142 [[commands]]
 143 COMMANDS
 144 --------
 145 The following commands also have their own nloption:--help option.
 146
 147
 148 Tracing sessions
 149 ~~~~~~~~~~~~~~~~
 150 linklttng:lttng-create(1)::
 151     Create a tracing session.
 152
 153 linklttng:lttng-destroy(1)::
 154     Tear down tracing sessions.
 155
 156 linklttng:lttng-load(1)::
 157     Load tracing session configurations.
 158
 159 linklttng:lttng-metadata(1)::
 160     Manage an LTTng tracing session's metadata generation.
 161
 162 linklttng:lttng-save(1)::
 163     Save tracing session configurations.
 164
 165 linklttng:lttng-set-session(1)::
 166     Set current tracing session.
 167
 168
 169 Channels
 170 ~~~~~~~~
 171 linklttng:lttng-add-context(1)::
 172     Add context fields to a channel.
 173
 174 linklttng:lttng-disable-channel(1)::
 175     Disable tracing channels.
 176
 177 linklttng:lttng-enable-channel(1)::
 178     Create or enable tracing channels.
 179
 180
 181 Event rules
 182 ~~~~~~~~~~~
 183 linklttng:lttng-disable-event(1)::
 184     Disable event rules.
 185
 186 linklttng:lttng-enable-event(1)::
 187     Create or enable event rules.
 188
 189
 190 Status
 191 ~~~~~~
 192 linklttng:lttng-list(1)::
 193     List tracing sessions, domains, channels, and events.
 194
 195 linklttng:lttng-status(1)::
 196     Get the status of the current tracing session.
 197
 198
 199 Control
 200 ~~~~~~~
 201 linklttng:lttng-snapshot(1)::
 202     Snapshot buffers of current tracing session.
 203
 204 linklttng:lttng-start(1)::
 205     Start tracing.
 206
 207 linklttng:lttng-stop(1)::
 208     Stop tracing.
 209
 210
 211 Resource tracking
 212 ~~~~~~~~~~~~~~~~~
 213 linklttng:lttng-track(1)::
 214     Track specific system resources.
 215
 216 linklttng:lttng-untrack(1)::
 217     Untrack specific system resources.
 218
 219
 220 Miscellaneous
 221 ~~~~~~~~~~~~~
 222 linklttng:lttng-calibrate(1)::
 223     Quantify LTTng overhead.
 224
 225 linklttng:lttng-help(1)::
 226     Display help information about a command.
 227
 228 linklttng:lttng-version(1)::
 229     Show version information.
 230
 231 linklttng:lttng-view(1)::
 232     Start trace viewer.
 233
 234
 235 include::common-cmd-footer.txt[]
 236
 237
 238 SEE ALSO
 239 --------
 240 linklttng:lttng-sessiond(8),
 241 linklttng:lttng-relayd(8),
 242 linklttng:lttng-crash(1),
 243 linklttng:lttng-ust(3),
 244 linklttng:babeltrace(1)