lttng-add-context(1)
====================
-:revdate: 3 May 2021
+:revdate: 14 June 2021
NAME
Without the option:--list option::
Add one or more context fields to be recorded by LTTng to the event
- records of a given channel, or of all the channels of:
+ records of:
+
With the option:--session='SESSION' option:::
- The tracing session named 'SESSION'.
+ The recording session named 'SESSION'.
Without the option:--session option:::
- The current tracing session (see man:lttng-concepts(7) to learn more
- about the current tracing session).
+ The current recording session (see man:lttng-concepts(7) to learn
+ more about the current recording session).
+
+With the option:--channel='CHANNEL':::
+ The channel named 'CHANNEL'.
+
+Without the option:--channel option:::
+ *All* the channels of the selected recording session.
With the option:--list option::
List the available context field types.
-See man:lttng-concepts(7) to learn more about tracing sessions and
+See man:lttng-concepts(7) to learn more about recording sessions and
channels.
-Without the option:--channel option, LTTng adds context fields to be
-recorded to the event records of *all* the channels of the selected
-tracing session.
-
Repeat the option:--type='TYPE' option to add more than one context
field to be recorded. 'TYPE' is one of:
* An LTTng application-specific context field name:
+
+--
[verse]
$app.'PROVIDER':__TYPE__
+
'TYPE'::
Context type name.
+--
++
+Only available with the option:--jul and option:--log4j options.
IMPORTANT: Make sure to **single-quote** 'TYPE' when you run the
`add-context` command from a shell, as `$` is a special character for
variable substitution in most shells.
NOTE: As of LTTng{nbsp}{lttng_version}, you may :not: add context fields
-to be recorded to the event records of a given channel once its tracing
-session has been started (see man:lttng-start(1)) at least once.
+to be recorded to the event records of a given channel once its
+recording session has been started (see man:lttng-start(1)) at least
+once.
+
+See the ``<<examples,EXAMPLES>>'' section below for usage examples.
include::common-lttng-cmd-options-head.txt[]
option:-c 'CHANNEL', option:--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
- tracing session.
+ recording session.
option:-s 'SESSION', option:--session='SESSION'::
Add context fields to be recorded to the event records of one or
- more channels of the tracing session named 'SESSION' instead of the
- current tracing session.
+ more channels of the recording session named 'SESSION' instead of
+ the current recording session.
Context field type
include::common-lttng-cmd-after-options.txt[]
+[[examples]]
+EXAMPLES
+--------
+.List the available context field types.
+====
+See the option:--list option.
+
+[role="term"]
+----
+$ lttng add-context --list
+----
+====
+
+.Add a single statically-known context field to be recorded to all the Linux kernel channels of the current recording session.
+====
+[role="term"]
+----
+$ lttng add-context --kernel --type=pid
+----
+====
+
+.Add three statically-known context fields to be recorded to a specific user space channel of a specific recording session.
+====
+See the option:--session and option:--channel options.
+
+[role="term"]
+----
+$ lttng add-context --userspace --session=my-session \
+ --channel=my-channel \
+ --type=vpid --type=procname --type=ip
+----
+====
+
+.Add a perf counter context field to be recorded to a specific Linux kernel channel of the current recording session.
+====
+See the option:--channel option.
+
+[role="term"]
+----
+$ lttng add-context --kernel --channel=my-channel \
+ --type=perf:cpu:cache-misses
+----
+====
+
+.Add an LTTng application-specific context field to be recorded to all the JUL channels of the current recording session.
+====
+[role="term"]
+----
+$ lttng add-context --jul --type='$app.my_server:user_cnt'
+----
+====
+
+
include::common-footer.txt[]