lttng-add-context(1) — Linux manual page


LTTNG-ADD-CONTEXT(1)          LTTng Manual          LTTNG-ADD-CONTEXT(1)

NAME         top

       lttng-add-context - Add context fields to an LTTng channel

SYNOPSIS         top

       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

DESCRIPTION         top

       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:

           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.

           Custom name to easily recognize the counter.

       Application-specific context fields can be added to a channel
       using the following syntax:



           Provider name.

           Context type name.


           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

OPTIONS         top

       General options are described in lttng(1).

       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.

       -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.

           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 available command options.

LIMITATIONS         top

       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.


           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
           lttng COMMAND --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 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         top

           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)

           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) and lttng-load(1)).


           $LTTNG_HOME defaults to $HOME when not explicitly set.

EXIT STATUS         top


           Command error

           Undefined command

           Fatal error

           Command warning (something went wrong during the command)

BUGS         top

       If you encounter any issue or usability problem, please report it
       on the LTTng bug tracker <

RESOURCES         top

       •   LTTng project website <>

       •   LTTng documentation <>

       •   Git repositories <>

       •   GitHub organization <>

       •   Continuous integration <>

       •   Mailing list <> for support and

       •   IRC channel <irc://>: #lttng on

COPYRIGHTS         top

       This program is part of the LTTng-tools project.

       LTTng-tools is distributed under the GNU General Public License
       version 2 <
       licenses/gpl-2.0.en.html>. See the LICENSE
       <> file
       for details.

THANKS         top

       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.

AUTHORS         top

       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

SEE ALSO         top


COLOPHON         top

       This page is part of the LTTng-Tools (    LTTng tools) project.
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       This page was obtained from the project's upstream Git repository
       ⟨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
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       (which is not part of the original manual page), send a mail to

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)