~~~~~~~~~~~~~~
There are four tracing session modes:
-Local mode::
+[[local-mode]]Local mode::
Traces the local system and writes the trace to the local
file system. The option:--output option specifies the trace path.
Using option:--set-url=file://'PATH' is the equivalent of using
written locally in the `$LTTNG_HOME/lttng-traces` directory
(`$LTTNG_HOME` defaults to `$HOME`).
-Network streaming mode::
+[[network-streaming-mode]]Network streaming mode::
Traces the local system and sends the trace over the network to
a listening relay daemon (see man:lttng-relayd(8)).
The option:--set-url, or option:--ctrl-url and option:--data-url
options set the trace output destination (see the
<<url-format,URL format>> section below).
-Snapshot mode::
+[[snapshot-mode]]Snapshot mode::
Traces the local system without writing the trace to the local file
system (implicit option:--no-output option). Channels are automatically
configured to be snapshot-ready on creation (see
The option:--set-url, or option:--ctrl-url and option:--data-url
options set the default snapshot output destination.
-Live mode::
+[[live-mode]]Live mode::
Traces the local system, sending trace data to an LTTng relay daemon
over the network (see man:lttng-relayd(8)). The
option:--set-url, or option:--ctrl-url and option:--data-url options
'NETPROTO'://('HOST' | 'IPADDR')[:__CTRLPORT__[:__DATAPORT__]][/'TRACEPATH']
The `file://` protocol targets the *local file system* and can only
-be used as the option:--set-url option's argument in _local mode_.
+be used as the option:--set-url option's argument when the session is
+created in <<local-mode,local>> or <<snapshot-mode,snapshot>> mode.
'TRACEPATH'::
Absolute path to trace files on the local file system.
-The other version is used for the _network streaming mode_.
+The other version is available when the session is created in
+<<network-streaming-mode,network streaming>>,
+<<snapshot-mode,snapshot>>, or <<live-mode,live>> mode.
'NETPROTO'::
Network protocol, amongst:
Mode selection
~~~~~~~~~~~~~~
option:--live[='DELAYUS']::
- Create the session in live mode. The optional 'DELAYUS' parameter,
- given in microseconds, is the maximum time the user can wait for
- the data to be flushed. This mode can be set with a network URL
- (options option:--set-url, or option:--ctrl-url and option:--data-url)
- and must have a relay daemon listening (see man:lttng-relayd(8)).
+ Create the session in <<live-mode,live mode>>.
++
+The optional 'DELAYUS' parameter, given in microseconds, is the
+maximum time the user can wait for the data to be flushed. This mode
+can be set with a network URL (options option:--set-url, or
+option:--ctrl-url and option:--data-url) and must have a relay
+daemon listening (see man:lttng-relayd(8)).
+
By default, 'DELAYUS' is {default_lttng_live_timer} and the network URL
is set to `net://127.0.0.1`.
option:--snapshot::
- Create the session in snapshot mode. This is the equivalent of using
- the option:--no-output option and creating all the channels of this
- new tracing session in overwrite mode with an `mmap` output type.
+ Create the session in <<snapshot-mode,snapshot mode>>.
+ This is the equivalent of using the option:--no-output option and
+ creating all the channels of this new tracing session in overwrite
+ mode with an `mmap` output type.
Output
~~~~~~
option:--no-output::
- Do not output any trace data.
+ In <<local-mode,local mode>>, do not output any trace data.
option:-o, option:--output='PATH'::
- Set trace output path to 'PATH'.
+ In <<local-mode,local mode>>, set trace output path to 'PATH'.
option:--shm-path='PATH'::
Create shared memory holding buffers at 'PATH'.
the session lifetime. This option sets both data
(option:--data-url option) and control (option:--ctrl-url option)
URLs at the same time.
++
+In <<local-mode,local>> mode, 'URL' must start with `file://` followed
+by the destination path on the local file system.
include::common-cmd-help-options.txt[]