NAME

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

SYNOPSIS

       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

       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.

OPTIONS

       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.

ENVIRONMENT VARIABLES

       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.

FILES

       $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.

EXIT STATUS

       0
           Success

       1
           Command error

       2
           Undefined command

       3
           Fatal error

       4
           Command warning (something went wrong during the command)

BUGS

       If you encounter any issue or usability problem, please report it on the LTTng bug tracker
       <https://bugs.lttng.org/projects/lttng-tools>.

RESOURCES

       •   LTTng project website <http://lttng.org>

       •   LTTng documentation <http://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

COPYRIGHTS

       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.

THANKS

       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.

AUTHORS

       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>.

SEE ALSO

       lttng(1)