doc/man/lttng-create.1.txt

   1 lttng-create(1)
   2 ===============
   3
   4
   5 NAME
   6 ----
   7 lttng-create - Create an LTTng tracing session
   8
   9
  10 SYNOPSIS
  11 --------
  12 Local mode:
  13
  14 [verse]
  15 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* [option:--shm-path='PATH']
  16       [option:--no-output | option:--output='PATH' | option:--set-url=file://'PATH'] ['SESSION']
  17
  18 Network streaming mode:
  19
  20 [verse]
  21 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* [option:--shm-path='PATH']
  22       (option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL') ['SESSION']
  23
  24 Snapshot mode:
  25
  26 [verse]
  27 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* option:--snapshot [option:--shm-path='PATH']
  28       [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL'] ['SESSION']
  29
  30 Live mode:
  31
  32 [verse]
  33 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* option:--live[='DELAYUS'] [option:--shm-path='PATH']
  34       [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL'] ['SESSION']
  35
  36 Template:
  37 [verse]
  38 *lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* option:--template-path='TEMPLATE'] [option:--shm-path='PATH']
  39       [option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL']
  40
  41
  42 DESCRIPTION
  43 -----------
  44 The `lttng create` command creates a new tracing session.
  45
  46 A tracing session is a named container of channels, which in turn
  47 contain event rules. It is domain-agnostic, in that channels and event
  48 rules can be enabled for the user space tracer and/or the Linux
  49 kernel tracer.
  50
  51 On execution, an `.lttngrc` file is created, if it does not exist, in the
  52 user's home directory. This file contains the name of the current tracing
  53 session. When creating a new tracing session with `lttng create`, the
  54 current tracing session is set to this new tracing session. The
  55 man:lttng-set-session(1) command can be used to set the current
  56 tracing session without manually editing the `.lttngrc` file.
  57
  58 If 'SESSION' is omitted, a session name is automatically created having
  59 this form: `auto-YYYYmmdd-HHMMSS`. 'SESSION' *must not* contain the
  60 character `/`.
  61
  62 The option:--shm-path option can be used to specify the path to the
  63 shared memory holding the ring buffers. Specifying a location on an
  64 NVRAM file system makes it possible to retrieve the latest recorded
  65 trace data when the system reboots after a crash. To view the events
  66 of ring buffer files after a system crash, use the
  67 man:lttng-crash(1) utility.
  68
  69 Tracing sessions are destroyed using the man:lttng-destroy(1)
  70 command.
  71
  72
  73 Creation modes
  74 ~~~~~~~~~~~~~~
  75 There are four tracing session modes:
  76
  77 [[local-mode]]Local mode::
  78     Traces the local system and writes the trace to the local
  79     file system. The option:--output option specifies the trace path.
  80     Using option:--set-url=file://'PATH' is the equivalent of using
  81     option:--output='PATH'. The file system output can be disabled using
  82     the option:--no-output option.
  83 +
  84 If none of the options mentioned above are used, then the trace is
  85 written locally in the `$LTTNG_HOME/lttng-traces` directory
  86 (`$LTTNG_HOME` defaults to `$HOME`).
  87
  88 [[network-streaming-mode]]Network streaming mode::
  89     Traces the local system and sends the trace over the network to
  90     a listening relay daemon (see man:lttng-relayd(8)).
  91     The option:--set-url, or option:--ctrl-url and option:--data-url
  92     options set the trace output destination (see the
  93     <<url-format,URL format>> section below).
  94
  95 [[snapshot-mode]]Snapshot mode::
  96     Traces the local system without writing the trace to the local file
  97     system (implicit option:--no-output option). Channels are automatically
  98     configured to be snapshot-ready on creation (see
  99     man:lttng-enable-channel(1)). The man:lttng-snapshot(1)
 100     command is used to take snapshots of the current ring buffers.
 101     The option:--set-url, or option:--ctrl-url and option:--data-url
 102     options set the default snapshot output destination.
 103
 104 [[live-mode]]Live mode::
 105     Traces the local system, sending trace data to an LTTng relay daemon
 106     over the network (see man:lttng-relayd(8)). The
 107     option:--set-url, or option:--ctrl-url and option:--data-url options
 108     set the trace output destination. The live output URLs cannot use
 109     the `file://` protocol (see the <<url-format,URL format>>
 110     section below).
 111
 112
 113 [[url-format]]
 114 URL format
 115 ~~~~~~~~~~
 116 The option:--set-url, option:--ctrl-url, and option:--data-url options'
 117 arguments are URLs.
 118
 119 The format of those URLs is one of:
 120
 121 [verse]
 122 file://'TRACEPATH'
 123 'NETPROTO'://('HOST' | 'IPADDR')[:__CTRLPORT__[:__DATAPORT__]][/'TRACEPATH']
 124
 125 The `file://` protocol targets the *local file system* and can only
 126 be used as the option:--set-url option's argument when the session is
 127 created in <<local-mode,local>> or <<snapshot-mode,snapshot>> mode.
 128
 129 'TRACEPATH'::
 130     Absolute path to trace files on the local file system.
 131
 132 The other version is available when the session is created in
 133 <<network-streaming-mode,network streaming>>,
 134 <<snapshot-mode,snapshot>>, or <<live-mode,live>> mode.
 135
 136 'NETPROTO'::
 137     Network protocol, amongst:
 138 +
 139 --
 140 `net`::
 141     TCP over IPv4; the default values of 'CTRLPORT' and 'DATAPORT'
 142     are respectively {default_network_control_port} and
 143     {default_network_data_port}.
 144
 145 `net6`::
 146     TCP over IPv6: same default ports as the `net` protocol.
 147
 148 `tcp`::
 149     Same as the `net` protocol; can only be used with the
 150     option:--ctrl-url and option:--data-url options together.
 151
 152 `tcp6`::
 153     Same as the `net6` protocol; can only be used with the
 154     option:--ctrl-url and option:--data-url options together.
 155 --
 156
 157 ('HOST' | 'IPADDR')::
 158     Hostname or IP address (IPv6 address *must* be enclosed in brackets
 159     (`[` and `]`); see https://www.ietf.org/rfc/rfc2732.txt[RFC 2732]).
 160
 161 'CTRLPORT'::
 162     Control port.
 163
 164 'DATAPORT'::
 165     Data port.
 166
 167 'TRACEPATH'::
 168     Path of trace files on the remote file system. This path is relative
 169     to the base output directory set on the relay daemon side;
 170     see man:lttng-relayd(8).
 171
 172
 173 include::common-cmd-options-head.txt[]
 174
 175
 176 Mode selection
 177 ~~~~~~~~~~~~~~
 178 option:--live[='DELAYUS']::
 179     Create the session in <<live-mode,live mode>>.
 180 +
 181 The optional 'DELAYUS' parameter, given in microseconds, is the
 182 maximum time the user can wait for the data to be flushed. This mode
 183 can be set with a network URL (options option:--set-url, or
 184 option:--ctrl-url and option:--data-url) and must have a relay
 185 daemon listening (see man:lttng-relayd(8)).
 186 +
 187 By default, 'DELAYUS' is {default_lttng_live_timer} and the network URL
 188 is set to `net://127.0.0.1`.
 189
 190 option:--snapshot::
 191     Create the session in <<snapshot-mode,snapshot mode>>.
 192     This is the equivalent of using the option:--no-output option and
 193     creating all the channels of this new tracing session in overwrite
 194     mode with an `mmap` output type.
 195
 196
 197 Output
 198 ~~~~~~
 199 option:--no-output::
 200     In <<local-mode,local mode>>, do not output any trace data.
 201
 202 option:-o, option:--output='PATH'::
 203     In <<local-mode,local mode>>, set trace output path to 'PATH'.
 204
 205 option:--shm-path='PATH'::
 206     Create shared memory holding buffers at 'PATH'.
 207
 208
 209 URL
 210 ~~~
 211 See the <<url-format,URL format>> section above for more information
 212 about the syntax of the following options' 'URL' argument.
 213
 214 option:-C, option:--ctrl-url='URL'::
 215     Set control path URL to 'URL' (must use option:--data-url option
 216     also).
 217
 218 option:-D, option:--data-url='URL'::
 219     Set data path URL to 'URL' (must use option:--ctrl-url option
 220     also).
 221
 222 option:-U, option:--set-url='URL'::
 223     Set URL destination of the trace data to 'URL'. It is persistent for
 224     the session lifetime. This option sets both data
 225     (option:--data-url option) and control (option:--ctrl-url option)
 226     URLs at the same time.
 227 +
 228 In <<local-mode,local>> mode, 'URL' must start with `file://` followed
 229 by the destination path on the local file system.
 230
 231 TEMPLATE
 232 ~~~
 233 option:--template-path='TEMPLATE'::
 234     Create a session based on the specified template.
 235     Note: The mode selection flag have no effect when combined with the
 236     (option:--template-path option). Other options and arguments overrides
 237     the values present in the template when present.
 238
 239
 240 Name
 241 ~~~~
 242 option:--default-name::
 243     Generate a session name of the form `auto-YYYYmmdd-HHMMSS`.
 244
 245 include::common-cmd-help-options.txt[]
 246
 247
 248 include::common-cmd-footer.txt[]
 249
 250
 251 SEE ALSO
 252 --------
 253 man:lttng-destroy(1),
 254 man:lttng-set-session(1),
 255 man:lttng(1)