lttng-help man page

lttng-help — Display help information about an LTTng command




The lttng help command displays help information about an LTTng command.

This command is the equivalent of:

lttng COMMAND --help

where COMMAND is the name of the command about which to get help. If COMMAND is omitted, lttng help shows general help about the lttng(1) command.

The lttng help command 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.


General options are described in lttng(1).

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 available command options.

Environment Variables


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


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


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


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


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.



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.


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


User LTTng runtime and configuration directory.


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


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


$LTTNG_HOME defaults to $HOME when not explicitly set.

Exit Status




Command error


Undefined command


Fatal error


Command warning (something went wrong during the command)


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


· LTTng project website <http://lttng.org>

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

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

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

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

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

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


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-license…>. See the LICENSE <https://github.com/lttng/lttng-tools/bl…> file for details.


Special thanks to Michel Dagenais and the DORSAL laboratory <http://www.dorsal.polymtl.ca/> at École Polytechnique de Montréal 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.


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 Jérémie Galarneau <mailto:jeremie.galarneau@efficios.com>.

See Also


Referenced By

lttng(1), lttng-add-context(1), lttng-calibrate(1), lttng-create(1), lttng-destroy(1), lttng-disable-channel(1), lttng-disable-event(1), lttng-enable-channel(1), lttng-enable-event(1), lttng-list(1), lttng-load(1), lttng-metadata(1), lttng-save(1), lttng-set-session(1), lttng-snapshot(1), lttng-start(1), lttng-status(1), lttng-stop(1), lttng-track(1), lttng-untrack(1), lttng-version(1), lttng-view(1).

Explore man page connections for lttng-help(1).

LTTng 2.8.2 10/11/2016