lttng-create(1)
===============
-:revdate: 3 May 2021
+:revdate: 7 December 2021
NAME
----
-lttng-create - Create an LTTng tracing session
+lttng-create - Create an LTTng recording session
SYNOPSIS
--------
-Create a local mode tracing session:
+Create a local mode recording session:
[verse]
*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] [option:--shm-path='DIR']
[option:--no-output | option:--output='DIR' | option:--set-url=**file://**__DIR__]
-Create a network streaming mode tracing session:
+Create a network streaming mode recording session:
[verse]
*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] [option:--shm-path='DIR']
(option:--set-url='URL' | option:--ctrl-url='URL' option:--data-url='URL')
-Create a snapshot mode tracing session:
+Create a snapshot mode recording session:
[verse]
*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] option:--snapshot [option:--shm-path='DIR']
[option:--no-output | option:--output='DIR' | option:--set-url='URL' |
option:--ctrl-url='URL' option:--data-url='URL']
-Create a live mode tracing session:
+Create a live mode recording session:
[verse]
*lttng* ['linkgenoptions:(GENERAL OPTIONS)'] *create* ['SESSION'] option:--live[='DELAYUS']
DESCRIPTION
-----------
-The `lttng create` command creates a new tracing session for your Unix
+The `lttng create` command creates a new recording session for your Unix
user within the connected session daemon (see the ``Session daemon
connection'' section of man:lttng(1) to learn how a user application
connects to a session daemon).
-See man:lttng-concepts(7) to learn more about tracing sessions.
+See man:lttng-concepts(7) to learn more about recording sessions.
-Without the 'SESSION' argument, LTTng automatically generates a tracing
+Without the 'SESSION' argument, LTTng automatically generates a recording
session name having the ++auto-++__YYYYmmdd__++-++__HHMMSS__ form, where
'YYYYmmdd' and 'HHMMSS' are the creation date and time. 'SESSION' may
:not: contain the character `/`.
holding the channel ring buffers with the option:--shm-path option.
Specifying a location on an NVRAM file system makes it possible to
recover the latest recorded trace data when the system reboots after a
-crash with the man:lttng-crash(1) utility.
+crash with the man:lttng-crash(1) utility. Note that, as of
+LTTng{nbsp}{lttng_version}, this feature is only available for user
+space channels.
-By default, the `create` command automatically spawns a session daemon
-for your Unix user if none is currently running. Override the path of
-the session daemon binary to spawn with the general
-genoption:--sessiond-path option. Avoid automatically spawning a session
-daemon with the general genoption:--no-sessiond option.
+By default, the `create` command automatically spawns:
-On success, the `create` command sets the current tracing session (see
-man:lttng-concepts(7) to learn more) to the created tracing session.
+* A session daemon for your Unix user if none is currently running.
++
+Override the path of the session daemon binary to spawn with the
+general genoption:--sessiond-path option.
++
+Avoid automatically spawning a session daemon with the general
+genoption:--no-sessiond option.
+
+* A relay daemon (see man:lttng-relayd(8)) if all the following
+ statements are true:
++
+--
+* You specify the option:--live option.
+
+* You don't specify any of the option:--set-url, option:--ctrl-url, or
+ option:--data-url options.
+
+* No relay daemon is currently listening for TCP connections on
+ +127.0.0.1:{default_network_viewer_port}+ (default LTTng live reader
+ connection address and port).
+--
++
+In this case, the `create` command spawns a relay daemon as such:
++
+[verse]
+*lttng-relayd* nloption:--live-port=**tcp://localhost:{default_network_viewer_port}**
+{nbsp}
++
+Override the path of the relay daemon binary to spawn with the general
+genoption:--relayd-path option.
+
+On success, the `create` command sets the current recording session (see
+man:lttng-concepts(7) to learn more) to the created recording session.
-Show the status of the current tracing session with the
+See the ``<<examples,EXAMPLES>>'' section below for usage examples.
+
+Show the status of the current recording session with the
man:lttng-status(1) command.
-List the tracing sessions of your Unix user, or of all users if
+List the recording sessions of your Unix user, or of all users if
your Unix user is `root`, within the connected session daemon with the
man:lttng-list(1) command.
-Start and stop a tracing session with the man:lttng-start(1) and
+Start and stop a recording session with the man:lttng-start(1) and
man:lttng-stop(1) commands.
-Save and load a tracing session with the man:lttng-save(1) and
+Save and load a recording session with the man:lttng-save(1) and
man:lttng-load(1) commands.
Allow and disallow specific processes to record events with the
man:lttng-track(1) and man:lttng-untrack(1) commands.
-Archive the current trace chunk of (rotate) a tracing session with the
+Archive the current trace chunk of (rotate) a recording session with the
man:lttng-rotate(1) command.
-Destroy a tracing session with the man:lttng-destroy(1) command.
+Destroy a recording session with the man:lttng-destroy(1) command.
[[modes]]
-Tracing session modes
-~~~~~~~~~~~~~~~~~~~~~
-As documented in man:lttng-concepts(7), LTTng offers four tracing
+Recording session modes
+~~~~~~~~~~~~~~~~~~~~~~~
+As documented in man:lttng-concepts(7), LTTng offers four recording
session modes:
[[local-mode]]Local mode::
Otherwise:::
A subdirectory, under the `$LTTNG_HOME/lttng-traces` (`$LTTNG_HOME`
defaults to `$HOME`) directory, of which the name contains the
- tracing session name and the date/time.
+ recording session name and the date/time.
[[network-streaming-mode]]Network streaming mode::
Send the trace data over the network to a listening relay daemon
+
Set the trace output destination with the option:--set-url option, or
with the option:--ctrl-url and option:--data-url options (see the
-<<url-format,URL format>> section below).
+``<<url-format,URL format>>'' section below).
[[snapshot-mode]]Snapshot mode (option:--snapshot option)::
Only write the trace data to the local file system or send it to a
With this mode, LTTng:
+
With the option:--no-output option:::
- Does :not: add any snapshot output to the created tracing
+ Does :not: add any snapshot output to the created recording
session.
With the option:--output option, the option:--set-url option, or the option:--ctrl-url and option:--data-url options:::
Adds a snapshot output named `snapshot-1` using the provided
- path or URL(s) to the created tracing session.
+ path or URL(s) to the created recording session.
Otherwise:::
Adds an automatic snapshot output named `snapshot-1` to the created
- tracing session.
+ recording session.
+
The automatic snapshot output is a subdirectory, under the
`$LTTNG_HOME/lttng-traces` (`$LTTNG_HOME` defaults to `$HOME`)
-directory, of which the name contains the tracing session name and the
+directory, of which the name contains the recording session name and the
date/time.
[[live-mode]]Live mode (option:--live option)::
+
Set the trace output destination with the option:--set-url='URL' option,
or with the option:--ctrl-url='URL' and option:--data-url='URL' options
-(see the <<url-format,URL format>> section below). 'URL' may :not: start
-with `file://`.
+(see the ``<<url-format,URL format>>'' section below). 'URL' may :not:
+start with `file://`.
[[url-format]]
{nbsp}
+
The `file://` protocol targets the *local file system*: you may only use
-such an URL with the option:--set-url option when you create the tracing
-session in local or snapshot mode (see the <<modes,Tracing session
-modes>> section above).
+such an URL with the option:--set-url option when you create the
+recording session in local or snapshot mode (see the ``<<modes,Recording
+session modes>>'' section above).
+
'TRACEDIR':::
Absolute path to the directory containing the trace data on the
'NETPROTO'://('HOST' | 'IPADDR')[:__CTRLPORT__[:__DATAPORT__]][/'TRACEDIR']
{nbsp}
+
-This format is only available when you create the tracing session in
+This format is only available when you create the recording session in
network streaming, snapshot (option:--snapshot), or live (option:--live)
-mode (see the <<modes,Tracing session modes>> section above).
+mode (see the ``<<modes,Recording session modes>>'' section above).
+
'NETPROTO':::
Network protocol, amongst:
daemon (see the nloption:--output option of man:lttng-relayd(8)).
-include::common-cmd-options-head.txt[]
+include::common-lttng-cmd-options-head.txt[]
Mode selection
~~~~~~~~~~~~~~
-See the <<modes,Tracing session modes>> section above.
+See the ``<<modes,Recording session modes>>'' section above.
At most one of:
option:--live[='DELAYUS']::
- Create the tracing session in live mode.
+ Create the recording session in live mode.
+
The optional 'DELAYUS' argument is the maximum time (in µs) you can wait
for the data to be flushed (sent to the connected LTTng relay daemon).
(see man:lttng-relayd(8)).
option:--snapshot::
- Create the tracing session in snapshot mode.
+ Create the recording session in snapshot mode.
+
This is equivalent to:
+
+
--
With the option:--no-output option::
- Not adding any snapshot output after LTTng creates the tracing
+ Not adding any snapshot output after LTTng creates the recording
session.
With the option:--output option, the option:--set-url option, or the option:--ctrl-url and option:--data-url options::
Adding a snapshot output named `snapshot-1` using the provided path
- or URL(s) immediately after LTTng creates the tracing session.
+ or URL(s) immediately after LTTng creates the recording session.
Otherwise::
Adding an automatic snapshot output named `snapshot-1` immediately
- after LTTng creates the tracing session.
+ after LTTng creates the recording session.
+
The automatic snapshot output is a subdirectory, under the
`$LTTNG_HOME/lttng-traces` (`$LTTNG_HOME` defaults to `$HOME`)
-directory, of which the name contains the tracing session name and the
+directory, of which the name contains the recording session name and the
date/time.
--
-* Forcing all the channels to be created for the tracing session to be
+* Forcing all the channels to be created for the recording session to be
configured with the nloption:--override and nloption:--output=++mmap++
options (see man:lttng-enable-channel(1)).
Output
~~~~~~
option:--no-output::
- Depending on the tracing session mode (see the <<modes,Tracing
- session modes>> section above):
+ Depending on the recording session mode (see the ``<<modes,Recording
+ session modes>>'' section above):
+
Local mode:::
Disable the file system output.
Snapshot mode (option:--snapshot option):::
- Do :not: add a snapshot output after creating the tracing session.
+ Do :not: add a snapshot output after creating the recording session.
option:-o 'DIR', option:--output='DIR'::
Equivalent to option:--set-url=++file://++__DIR__.
option:--shm-path='DIR'::
Set the path of the directory containing the shared memory files
holding the channel ring buffers to 'DIR' on the local file sytem.
++
+NOTE: As of LTTng{nbsp}{lttng_version}, LTTng only considers this option
+for user space (including Java and Python) channels, but this may change
+in the future.
URL
~~~
-See the <<url-format,URL format>> section above to learn more about the
-syntax of the 'URL' argument of the following options.
+See the ``<<url-format,URL format>>'' section above to learn more about
+the syntax of the 'URL' argument of the following options.
option:-C 'URL', option:--ctrl-url='URL'::
Set the control path URL to 'URL'.
+
You must also use the option:--data-url option.
+
-Not available in local mode (see the <<modes,Tracing session modes>>
-section above).
+Not available in local mode (see the ``<<modes,Recording session
+modes>>'' section above).
+
In snapshot mode, this is equivalent to using the nloption:--ctrl-url
option of the `add-output` action of the man:lttng-snapshot(1) command
-immediately after creating the tracing session.
+immediately after creating the recording session.
option:-D 'URL', option:--data-url='URL'::
Set the trace data path URL to 'URL'.
+
You must also use the option:--ctrl-url option.
+
-Not available in local mode (see the <<modes,Tracing session modes>>
-section above).
+Not available in local mode (see the ``<<modes,Recording session
+modes>>'' section above).
+
In snapshot mode, this is equivalent to using the nloption:--data-url
option of the `add-output` action of the man:lttng-snapshot(1) command
-immediately after creating the tracing session.
+immediately after creating the recording session.
option:-U 'URL', option:--set-url='URL'::
Set the destination URL of the control path and trace data to 'URL'.
+
-This URL remains unchanged as long as the tracing session exists.
+This URL remains unchanged as long as the recording session exists.
+
-Depending on the tracing session mode (see the <<modes,Tracing session
-modes>> section above):
+Depending on the recording session mode (see the ``<<modes,Recording
+session modes>>'' section above):
+
Local mode:::
'URL' must start with `file://`, followed with the destination
Snapshot mode (option:--snapshot option):::
Equivalent to using the 'URL' non-option argument of the
`add-output` action of the man:lttng-snapshot(1) command immediately
- after creating the tracing session.
+ after creating the recording session.
-include::common-cmd-help-options.txt[]
+include::common-lttng-cmd-help-options.txt[]
-include::common-cmd-footer.txt[]
+include::common-lttng-cmd-after-options.txt[]
+
+
+[[examples]]
+EXAMPLES
+--------
+.Create a normal mode recording session with a generated name.
+====
+[role="term"]
+----
+$ lttng create
+----
+====
+
+.Create a normal mode recording session with a custom name.
+====
+[role="term"]
+----
+$ lttng create my-session
+----
+====
+
+.Create a normal mode recording session with a specific output directory.
+====
+See the option:--output option.
+
+[role="term"]
+----
+$ lttng create --output=/path/to/traces
+----
+====
+
+.Create a network streaming mode recording session.
+====
+See the ``Output directory'' section of man:lttng-relayd(8) to
+understand where the relay daemon to connect to (`10.0.0.242`) writes
+the received traces.
+
+See the option:--set-url option.
+
+[role="term"]
+----
+$ lttng create --set-url=net://10.0.0.242/inv4
+----
+====
+
+.Create a snapshot mode recording session with a default snapshot output.
+====
+See the option:--snapshot option.
+
+[role="term"]
+----
+$ lttng create --snapshot
+----
+====
+
+.Create a snapshot mode recording session with a custom snapshot output.
+====
+See the option:--snapshot and option:--set-url options.
+
+[role="term"]
+----
+$ lttng create --snapshot \
+ --set-url=tcp://192.168.1.102:1234:5678/my-snapshots
+----
+====
+
+.Create a snapshot mode recording session with no snapshot output.
+====
+See the option:--snapshot and option:--no-output options.
+
+[role="term"]
+----
+$ lttng create --snapshot --no-output
+----
+====
+
+.Create an LTTng live mode recording session with a default relay daemon URL.
+====
+See the option:--live option.
+
+[role="term"]
+----
+$ lttng create --live
+----
+====
+
+.Create an LTTng live mode recording session with a custom live timer period and relay daemon URL.
+====
+See the option:--live and option:--set-url options.
+
+[role="term"]
+----
+$ lttng create --live=250000 \
+ --set-url=tcp://relayd34:4885:4886
+----
+====
+
+.Create a normal mode recording session with a custom directory containing the ring buffer shared memory files.
+====
+See the option:--shm-path option.
+
+[role="term"]
+----
+$ lttng create my-session --shm-path=/mnt/nvram2/lttng
+----
+====
+
+
+include::common-footer.txt[]
SEE ALSO
--------
man:lttng(1),
-man:lttng-concepts(7),
man:lttng-destroy(1),
man:lttng-enable-channel(1),
-man:lttng-list(8),
-man:lttng-relayd(8),
+man:lttng-list(1),
man:lttng-rotate(1),
man:lttng-save(1),
-man:lttng-sessiond(8),
man:lttng-set-session(1),
man:lttng-start(1),
-man:lttng-status(8),
-man:lttng-track(1)
+man:lttng-status(1),
+man:lttng-track(1),
+man:lttng-concepts(7),
+man:lttng-relayd(8),
+man:lttng-sessiond(8)
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