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