lttng-load(1): Load LTTng tracing

lttng-load — Load LTTng tracing session configurations

Synopsis

lttng [GENERAL OPTIONS] load [--force] [--input-path=PATH]
      [--override-url=URL] [SESSION [--override-name=NAME]]

Description

The lttng load command loads the configurations of one or more tracing sessions from files.

The lttng load command is used in conjunction with the lttng-save(1) command to save and restore the complete configurations of tracing sessions. This includes the enabled channels and event rules, the context added to channels, the tracing activity, and more.

Once one or more tracing session configurations are loaded, they appear exactly as they were saved from the user’s point of view.

The following directories are searched, non-recursively, in this order for configuration files:

$LTTNG_HOME/.lttng/sessions ($LTTNG_HOME defaults to $HOME)
/usr/local/etc/lttng/sessions

The input path can be overridden with the --input-path option. When this option is specified, the default directories are NOT searched for configuration files. When it’s not specified, both default directories are searched for configuration files.

If the input path is a directory, then:

If SESSION is specified, the tracing session configuration named SESSION is searched for in all the files of this directory and loaded if found.
If SESSION is not specified, the --all option is implicit: all the tracing session configurations found in all the files in this directory are loaded.

If the input path is a file, then:

If SESSION is specified, the tracing session configuration named SESSION is searched for in this file and loaded if found.
If SESSION is not specified, the --all option is implicit: all the tracing session configurations found in this file are loaded.

Aspects of the loaded configurations can be overridden at load time using the --override-url and --override-name options.

By default, existing tracing sessions are not overwritten when loading: the command fails. The --force option can be used to allow this.

Options

General options are described in lttng(1).

-a, --all

Load all tracing session configurations (default).

-f, --force

Overwrite existing tracing sessions when loading.

-i PATH, --input-path=PATH

Load tracing session configurations from PATH, either a directory or a file, instead of loading them from the default search directories.

--override-name=NAME

Override the name of the loaded tracing session configuration, SESSION, with NAME.

You must specify a tracing session name to load (SESSION) and NOT use the --all option when using this option.

--override-url=URL

Override the URL of the loaded tracing session configurations with URL.

This is the equivalent of the --set-url option of lttng-create(1). The validity of the URL override depends on the type of tracing session configurations to load. This option applies to all the loaded tracing session configurations.

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

LTTng project website <https://lttng.org>
LTTng documentation <https://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

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 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-load