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