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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | LIMITATIONS | ENVIRONMENT VARIABLES | FILES | EXIT STATUS | BUGS | RESOURCES | COPYRIGHTS | THANKS | AUTHORS | SEE ALSO | COLOPHON |
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LTTNG-ADD-CONTEXT(1) LTTng Manual LTTNG-ADD-CONTEXT(1)
lttng-add-context - Add context fields to an LTTng channel
Add context fields to a channel:
lttng [GENERAL OPTIONS] add-context
(--kernel | --userspace | --jul | --log4j)
[--session=SESSION] [--channel=CHANNEL]
--type=TYPE [--type=TYPE]...
List the available context fields:
lttng [GENERAL OPTIONS] add-context --list
The lttng add-context command adds one or more context fields to a
channel.
Channels are created with the lttng-enable-channel(1) command.
When context fields are added to a channel, all the events emitted
within this channel contain the dynamic values of those context
fields.
If the --session option is omitted, the current tracing session is
used. If the --channel option is omitted, the context fields are
added to all the selected tracing session’s channels.
Many context fields can be added to a channel at once by repeating
the --type option.
perf counters are available as per-CPU (perf:cpu: prefix) as well
as per-thread (perf:thread: prefix) counters. Currently, per-CPU
counters can only be used in the Linux kernel tracing domain,
while per-thread counters can only be used in the user space
tracing domain.
It is also possible to enable PMU counters by raw ID using the
perf:cpu:raw:rN:NAME (Linux kernel tracing domain) or
perf:thread:raw:rN:NAME (user space tracing domain), with:
N
A hexadecimal event descriptor which is the same format as
used by perf-record(1): a concatenation of the event number
and umask value provided by the processor’s manufacturer. The
possible values for this field are processor-specific.
NAME
Custom name to easily recognize the counter.
Application-specific context fields can be added to a channel
using the following syntax:
$app.PROVIDER:TYPE
with:
PROVIDER
Provider name.
TYPE
Context type name.
Note
Make sure to single-quote the type when running the command
from a shell, as $ is a special character for variable
substitution in most shells.
Use the --list option without other arguments to list the
available context field names.
See the LIMITATIONS section below for a list of limitations to
consider.
General options are described in lttng(1).
Domain
One of:
-j, --jul
Add context to channel in the java.util.logging (JUL) domain.
-k, --kernel
Add context to channel in the Linux kernel domain.
-l, --log4j
Add context to channel in the Apache log4j domain.
-u, --userspace
Add context to channel in the user space domain.
Target
-c CHANNEL, --channel=CHANNEL
Add context fields to a channel named CHANNEL instead of
adding them to all the channels.
-s SESSION, --session=SESSION
Add context fields to a channel in the tracing session named
SESSION instead of the current tracing session.
Context
--list
List the available context fields. Use this option alone.
-t TYPE, --type=TYPE
Add context field named TYPE. This option can be repeated as
many times as needed on the command-line.
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.
As of this version of LTTng, it is not possible to add context
fields to a channel once its tracing session has been started (see
lttng-start(1)) at least once.
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.
$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.
0
Success
1
Command error
2
Undefined command
3
Fatal error
4
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-
tools>.
• 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
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.
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>.
lttng(1)
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 man-pages@man7.org. This page was obtained
from the project's upstream Git repository
⟨git://git.lttng.org/lttng-tools.git⟩ on 2019-11-19. (At that
time, the date of the most recent commit that was found in the
repository was 2019-11-14.) 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 to
man-pages@man7.org
LTTng 2.12.0-pre 10/29/2018 LTTNG-ADD-CONTEXT(1)
Pages that refer to this page: lttng(1), lttng-enable-event(1), lttng-ust(3), babeltrace2-filter.lttng-utils.debug-info(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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