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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | ENVIRONMENT | FILES | EXAMPLES | RESOURCES | COPYRIGHT | THANKS | SEE ALSO | COLOPHON |
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LTTNG-ADD-CONTEXT(1) LTTng Manual LTTNG-ADD-CONTEXT(1)
lttng-add-context - Add context fields to be recorded by LTTng
Add context fields to be recorded to the event records of one or
more channels:
lttng [GENERAL OPTIONS] add-context
(--kernel | --userspace | --jul | --log4j | --log4j2)
[--session=SESSION] [--channel=CHANNEL]
--type=TYPE [--type=TYPE]...
List the available context field types:
lttng [GENERAL OPTIONS] add-context --list
The lttng add-context command can:
Without the --list option
Add one or more context fields to be recorded by LTTng to the
event records of:
With the --session=SESSION option
The recording session named SESSION.
Without the --session option
The current recording session (see lttng-concepts(7) to
learn more about the current recording session).
With the --channel=CHANNEL
The channel named CHANNEL.
Without the --channel option
All the channels of the selected recording session.
With the --list option
List the available context field types.
See lttng-concepts(7) to learn more about recording sessions and
channels.
Repeat the --type=TYPE option to add more than one context field
to be recorded. TYPE is one of:
• A statically-known, or built-in context field name.
• A perf counter name:
Per-CPU
Prefix: perf:cpu:
Only available with the --kernel option.
Per-thread
Prefix: perf:thread:
Only available with the --userspace, --jul, --log4j, or
--log4j2 option.
Add Performance Monitoring Unit (PMU) counter context fields
by raw ID with the perf:cpu:raw:rN:NAME (--kernel option) or
perf:thread:raw:rN:NAME (--userspace, --jul, --log4j, or
--log4j2 option) types, with:
N
A hexadecimal event descriptor which follows the
perf-record(1) format: a concatenation of the event number
and umask value which the manufacturer of the processor
provides.
The possible values for this part are processor-specific.
NAME
Custom name to identify the counter.
• An LTTng application-specific context field name:
$app.PROVIDER:TYPE
+ PROVIDER:: Provider name.
TYPE
Context type name.
Only available with the --jul, --log4j, and --log4j2 options.
Important
Make sure to single-quote TYPE when you run the add-context
command from a shell, as $ is a special character for variable
substitution in most shells.
Note
As of LTTng 2.15.1, you may NOT add context fields to be
recorded to the event records of a given channel once its
recording session has been started (see lttng-start(1)) at
least once.
See the “EXAMPLES” section below for usage examples.
See lttng(1) for GENERAL OPTIONS.
Tracing domain
One of:
-j, --jul
Add context fields to be recorded to the event records of one
or more channels of the java.util.logging (JUL) tracing
domain.
-k, --kernel
Add context fields to be recorded to the event records of one
or more channels of the Linux kernel tracing domain.
-l, --log4j
Add context fields to be recorded to the event records of one
or more channels of the Apache log4j 1.x tracing domain.
--log4j2
Add context fields to be recorded to the event records of one
or more channels of the Apache Log4j 2 tracing domain.
-u, --userspace
Add context fields to be recorded to the event records of one
or more channels of the user space tracing domain.
Recording target
-c CHANNEL, --channel=CHANNEL
Add context fields to be recorded to the event records of a
channel named CHANNEL instead of all the channels of the
selected recording session.
-s SESSION, --session=SESSION
Add context fields to be recorded to the event records of one
or more channels of the recording session named SESSION
instead of the current recording session.
Context field type
--list
List the available context field types.
You may NOT use this option with the --channel, --session, or
--type options.
-t TYPE, --type=TYPE
Add a context field having the type TYPE to be recorded.
Repeat this option to add more than one context field.
Program information
-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.
0
Success
1
Command error
2
Undefined command
3
Fatal error
4
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_LIST_LEGACY
Set to 1 to use the legacy output format (LTTng 2.14 and
earlier) for the lttng-list(1) command instead of the modern
output format.
Note that the legacy output doesn’t show anything related to
features introduced after LTTng 2.14.
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_NO_UTF_8
Set to 1 to NOT emit multi-byte UTF-8 sequences, even if the
locale claims to support it.
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_TERM_COLOR
Controls when to emit terminal SGR codes in the output.
The NO_COLOR environment variable overrides this.
One of:
auto (default)
Only emit SGR codes when the standard output is connected
to a color-capable terminal.
always
Always emit SGR codes.
never
Never emit SGR codes.
NO_COLOR
If set and not empty, then it’s equivalent to setting
LTTNG_TERM_COLOR to never.
See NO_COLOR <https://no-color.org/> to learn more.
$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)).
/usr/local/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 1. List the available context field types.
See the --list option.
$ lttng add-context --list
Example 2. Add a single statically-known context field to be
recorded to all the Linux kernel channels of the current recording
session.
$ lttng add-context --kernel --type=pid
Example 3. Add three statically-known context fields to be
recorded to a specific user space channel of a specific recording
session.
See the --session and --channel options.
$ lttng add-context --userspace --session=my-session \
--channel=my-channel \
--type=vpid --type=procname --type=ip
Example 4. Add a perf counter context field to be recorded to a
specific Linux kernel channel of the current recording session.
See the --channel option.
$ lttng add-context --kernel --channel=my-channel \
--type=perf:cpu:cache-misses
Example 5. Add an LTTng application-specific context field to be
recorded to all the JUL channels of the current recording session.
$ lttng add-context --jul --type='$app.my_server:user_cnt'
• LTTng project website <https://lttng.org>
• LTTng documentation <https://lttng.org/docs>
• LTTng bug tracker <https://bugs.lttng.org>
• Git repositories <https://git.lttng.org>
• GitHub organization <https://github.com/lttng>
• Continuous integration <https://ci.lttng.org/>
• Mailing list <https://lists.lttng.org/> for support and
development: lttng-dev@lists.lttng.org
• IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
• Mastodon <https://mastodon.social/@lttng>
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(1), lttng-enable-channel(1), lttng-concepts(7)
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
⟨https://github.com/lttng/lttng-tools.git⟩ on 2026-08-04. (At
that time, the date of the most recent commit that was found in
the repository was 2026-07-30.) 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 2.15.1 1 April 2025 LTTNG-ADD-CONTEXT(1)
Pages that refer to this page: lttng(1), lttng-add-trigger(1), lttng-enable-event(1), lttng-ust(3), babeltrace2-filter.lttng-utils.debug-info(7), lttng-concepts(7), lttng-event-rule(7)
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HTML rendering created 2026-09-09 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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