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LTTNG-SNAPSHOT(1)		 LTTng Manual		     LTTNG-SNAPSHOT(1)

NAME
       lttng-snapshot -	Take LTTng snapshots and configure snapshot outputs

SYNOPSIS
       Add a snapshot output:

       lttng [GENERAL OPTIONS] snapshot	add-output [--max-size=SIZE]
	     [--name=NAME] [--session=SESSION]
	     (--ctrl-url=URL --data-url=URL | URL)

       Remove a	snapshot output:

       lttng [GENERAL OPTIONS] snapshot	del-output [--session=SESSION]
	     (ID | NAME)

       List current snapshot outputs:

       lttng [GENERAL OPTIONS] snapshot	list-output [--session=SESSION]

       Take a snapshot:

       lttng [GENERAL OPTIONS] snapshot	record [--max-size=SIZE]
	     [--name=NAME] [--session=SESSION]
	     (--ctrl-url=URL --data-url=URL | URL)

DESCRIPTION
       The lttng snapshot command manages the snapshot outputs and takes
       snapshots.

       A snapshot is a dump of the current sub-buffers of all the channels of
       a given tracing session.	When a snapshot	is taken, the memory dump is
       sent to the registered snapshot outputs.

       The tracing session should be created in	snapshot mode to make sure
       taking snapshots	is allowed. This is done at tracing session creation
       time using the lttng-create(1) command.

       Note that, when a snapshot is taken, the	sub-buffers are	not cleared.
       This means that different recorded snapshots may	contain	the same
       events.

   Snapshot outputs
       Snapshot	outputs	are the	destinations of	snapshot files when a snapshot
       is taken	using the record action.

       As of this version, only	one snapshot output is allowed.

       A snapshot output can be	added using the	add-output action. The output
       destination URL is set using either the URL positional argument,	or
       both the	--ctrl-url and --data-url options. See lttng-create(1) to
       learn more about	the URL	format.

       A name can be assigned to an output when	adding it using	the --name
       option. This name is part of the	names of the snapshot files written to
       this output.

       By default, the snapshot	files can be as	big as the sum of the sizes of
       all the sub-buffers or all the channels of the selected tracing
       session.	The maximum total size of all the snapshot files can be
       configured using	the --max-size option.

       Snapshot	outputs	can be listed using the	list-output action.

       Snapshot	outputs	can be removed using the del-output action. The
       configured name can be used when	removing an output, or an ID as	listed
       by the list-output action.

   Taking a snapshot
       Taking a	snapshot of the	current	tracing	session	is as easy as:

	   lttng snapshot record

       This writes the snapshot	files to the configured	output.	It is possible
       to use a	custom,	unregistered output at record time using the same
       options supported by the	add-output action.

	   Note
	   Before taking a snapshot on a system	with a high event throughput,
	   it is recommended to	first run lttng	stop (see lttng-stop(1)).
	   Otherwise, the snapshot could contain "holes", the result of	the
	   tracers overwriting unconsumed trace	packets	during the record
	   operation. After the	snapshot is recorded, the tracers can be
	   started again with lttng start (see lttng-start(1)).

OPTIONS
       General options are described in	lttng(1).

   Target
       -s SESSION, --session=SESSION
	   Take	a snapshot of the sub-buffers of the channels contained	in the
	   tracing session named SESSION instead of the	current	tracing
	   session.

   Snapshot output
       -C URL, --ctrl-url=URL
	   Set control path URL	to URL (must use --data-url option also).

       -D URL, --data-url=URL
	   Set data path URL to	URL (must use --ctrl-url option	also).

       -m SIZE,	--max-size=SIZE
	   Limit the total size	of all the snapshot files written when
	   recording a snapshot	to SIZE	bytes. The k (kiB), M (MiB), and G
	   (GiB) suffixes are supported.

       -n NAME,	--name=NAME
	   Assign the name NAME	to the snapshot	output.

   Program information
       -h, --help
	   Show	command	help.

	   This	option,	like lttng-help(1), attempts to	launch /usr/bin/man to
	   view	the command's man page.	The path to the	man pager can be
	   overridden by the LTTNG_MAN_BIN_PATH	environment variable.

       --list-options
	   List	available command options.

ENVIRONMENT VARIABLES
       LTTNG_ABORT_ON_ERROR
	   Set to 1 to abort the process after the first error is encountered.

       LTTNG_HOME
	   Overrides the $HOME environment variable. Useful when the user
	   running the commands	has a non-writable home	directory.

       LTTNG_MAN_BIN_PATH
	   Absolute path to the	man pager to use for viewing help information
	   about LTTng commands	(using lttng-help(1) or	lttng COMMAND --help).

       LTTNG_SESSION_CONFIG_XSD_PATH
	   Path	in which the session.xsd session configuration XML schema may
	   be found.

       LTTNG_SESSIOND_PATH
	   Full	session	daemon binary path.

	   The --sessiond-path option has precedence over this environment
	   variable.

       Note that the lttng-create(1) command can spawn an LTTng	session	daemon
       automatically if	none is	running. See lttng-sessiond(8) for the
       environment variables influencing the execution of the session daemon.

FILES
       $LTTNG_HOME/.lttngrc
	   User	LTTng runtime configuration.

	   This	is where the per-user current tracing session is stored
	   between executions of lttng(1). The current tracing session can be
	   set with lttng-set-session(1). See lttng-create(1) for more
	   information about tracing sessions.

       $LTTNG_HOME/lttng-traces
	   Default output directory of LTTng traces. This can be overridden
	   with	the --output option of the lttng-create(1) command.

       $LTTNG_HOME/.lttng
	   User	LTTng runtime and configuration	directory.

       $LTTNG_HOME/.lttng/sessions
	   Default location of saved user tracing sessions (see	lttng-save(1)
	   and lttng-load(1)).

       /usr/local/etc/lttng/sessions
	   System-wide location	of saved tracing sessions (see lttng-save(1)
	   and lttng-load(1)).

	   Note
	   $LTTNG_HOME defaults	to $HOME when not explicitly set.

EXIT STATUS
       0
	   Success

       1
	   Command error

       2
	   Undefined command

       3
	   Fatal error

       4
	   Command warning (something went wrong during	the command)

BUGS
       If you encounter	any issue or usability problem,	please report it on
       the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-tools>.

RESOURCES
       o   LTTng project website <http://lttng.org>

       o   LTTng documentation <http://lttng.org/docs>

       o   Git repositories <http://git.lttng.org>

       o   GitHub organization <http://github.com/lttng>

       o   Continuous integration <http://ci.lttng.org/>

       o   Mailing list	<http://lists.lttng.org> for support and development:
	   lttng-dev@lists.lttng.org

       o   IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net

COPYRIGHTS
       This program is part of the LTTng-tools project.

       LTTng-tools is distributed under	the GNU	General	Public License version
       2 <http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html>. See the
       LICENSE <https://github.com/lttng/lttng-tools/blob/master/LICENSE> file
       for details.

THANKS
       Special thanks to Michel	Dagenais and the DORSAL	laboratory
       <http://www.dorsal.polymtl.ca/> at Ecole	Polytechnique de Montreal for
       the LTTng journey.

       Also thanks to the Ericsson teams working on tracing which helped us
       greatly with detailed bug reports and unusual test cases.

AUTHORS
       LTTng-tools was originally written by Mathieu Desnoyers,	Julien
       Desfossez, and David Goulet. More people	have since contributed to it.

       LTTng-tools is currently	maintained by Jeremie Galarneau
       <mailto:jeremie.galarneau@efficios.com>.

SEE ALSO
       lttng(1)

LTTng 2.9.3			  01/09/2017		     LTTNG-SNAPSHOT(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT VARIABLES | FILES | EXIT STATUS | BUGS | RESOURCES | COPYRIGHTS | THANKS | AUTHORS | SEE ALSO

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