The lttng start command starts the various LTTng tracers for a given
inactive tracing session.
Starting the LTTng tracers has the effect that all enabled event
rules within enabled channels can make their target event sources
emit trace events. Whether they are recorded to the local file
system, sent over the network, or not recorded at all depends on the
specific configuration of the tracing session in which tracing is
started. See lttng-create(1) for different session modes.
A tracing session with running tracers is said to be active. Active
tracing sessions can return to the inactive state using the
If SESSION is omitted, the LTTng tracers are started for the current
tracing session (see lttng-create(1) for more information about the
current tracing session). Otherwise, they are started for the
existing tracing session named SESSION. lttng list outputs all the
existing tracing sessions (see lttng-list(1)).
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.
Set to 1 to abort the process after the first error is
Overrides the $HOME environment variable. Useful when the user
running the commands has a non-writable home directory.
Absolute path to the man pager to use for viewing help
information about LTTng commands (using lttng-help(1) or lttngCOMMAND --help).
Path in which the session.xsd session configuration XML schema
may be found.
Full session daemon binary path.
The --sessiond-path option has precedence over this environment
Note that the lttng-create(1) command can spawn an LTTng session
daemon automatically if none is running. See lttng-sessiond(8) for
the environment variables influencing the execution of the session
User LTTng runtime configuration.
This is where the per-user current tracing session is stored
between executions of lttng(1). The current tracing session can
be set with lttng-set-session(1). See lttng-create(1) for more
information about tracing sessions.
Default output directory of LTTng traces. This can be overridden
with the --output option of the lttng-create(1) command.
User LTTng runtime and configuration directory.
Default location of saved user tracing sessions (see
lttng-save(1) and lttng-load(1)).
System-wide location of saved tracing sessions (see lttng-save(1)
Note$LTTNG_HOME defaults to $HOME when not explicitly set.
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
LTTng-tools is currently maintained by Jérémie Galarneau
This page is part of the LTTng-Tools ( LTTng tools) project.
Information about the project can be found at ⟨http://lttng.org/⟩.
It is not known how to report bugs for this man page; if you know,
please send a mail to email@example.com. This page was obtained
from the project's upstream Git repository
⟨git://git.lttng.org/lttng-tools.git⟩ on 2017-03-13. If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
LTTng 2.10.0-pre 03/13/2017 LTTNG-START(1)