$
lttng start
lttng-start — Start one or more LTTng recording session
lttng [GENERAL OPTIONS] start [--all|--glob=PATTERN|SESSION]
The lttng start command starts one or more recording sessions, that
is, it activates the LTTng tracers for:
SESSION argument
The recording session named SESSION.
--glob=PATTERN option
The recording sessions of which the globbing pattern
PATTERN matches the name.
--all option
All the recording sessions of the connected session daemon for
your Unix user, or for all users if your Unix user is root, as
listed in the output of lttng list (see lttng-list(1)).
See the “Session daemon connection” section of lttng(1) to learn how a user application connects to a session daemon.
The current recording session.
See lttng-concepts(7) to learn more about the current recording session.
See lttng-concepts(7) to learn more about recording sessions.
The selected recording session(s) must be inactive (stopped). A recording session is inactive on creation (see lttng-create(1)).
A start-session trigger action can also start a recording session
(see lttng-add-trigger(1)).
See the “EXAMPLES” section below for usage examples.
Stop one or more active recording sessions with the lttng-stop(1) command.
See lttng(1) for GENERAL OPTIONS.
-h, --help
Show help.
This option attempts to launch /usr/bin/man to view this manual page.
Override the manual pager path with the LTTNG_MAN_BIN_PATH environment
variable.
--list-options
List available command options and quit.
-a, --all
Start all the recording sessions of your Unix user, or of all
users if your Unix user is root, as listed in the output of
lttng-list(1).
-g PATTERN, --glob=PATTERN
Start the recording sessions of which the
globbing pattern PATTERN matches the name.
In PATTERN, the * character means “match anything”. To match
a literal * character, use \*.
Success
Command error
Undefined command
Fatal error
Command warning (something went wrong during the command)
LTTNG_ABORT_ON_ERROR
Set to 1 to abort the process after the first error is
encountered.
LTTNG_HOME
Path to the LTTng home directory.
Defaults to $HOME.
Useful when the Unix user running the commands has a non-writable home directory.
LTTNG_MAN_BIN_PATH
Absolute path to the manual pager to use to read the LTTng
command-line help (with lttng-help(1) or with the
--help option) instead of /usr/bin/man.
LTTNG_SESSION_CONFIG_XSD_PATH
Path to the directory containing the session.xsd recording session
configuration XML schema.
LTTNG_SESSIOND_PATH
Absolute path to the LTTng session daemon binary (see lttng-sessiond(8)) to spawn from the lttng-create(1) command.
The --sessiond-path general option overrides this environment
variable.
$LTTNG_HOME/.lttngrc
Unix user’s LTTng runtime configuration.
This is where LTTng stores the name of the Unix user’s current recording session between executions of lttng(1). lttng-create(1) and lttng-set-session(1) set the current recording session.
$LTTNG_HOME/lttng-traces
Default output directory of LTTng traces in local and snapshot modes.
Override this path with the --output option of the
lttng-create(1) command.
$LTTNG_HOME/.lttng
Unix user’s LTTng runtime and configuration directory.
$LTTNG_HOME/.lttng/sessions
Default directory containing the Unix user’s saved recording session configurations (see lttng-save(1) and lttng-load(1)).
/etc/lttng/sessions
Directory containing the system-wide saved recording session configurations (see lttng-save(1) and lttng-load(1)).
Note:$LTTNG_HOME defaults to the value of the HOME environment
variable.
Example:Start the current recording session.
$
lttng start
Example:Start a specific recording session.
$
lttng start my-session
Example:Start all the recording sessions.
See the --all option.
$
lttng start --all
Example:Start all the recording sessions of which the name ends with foo.
See the --glob option.
$
lttng start --glob='*foo'
Mailing list for support and
development: lttng-dev@lists.lttng.org
IRC channel: #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. See the
LICENSE file
for details.
Special thanks to Michel Dagenais and the DORSAL laboratory 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.