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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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NAME | DESCRIPTION | INITIALIZATION PARAMETERS | PORTS | BUGS | RESOURCES | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON |
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BABELTRACE2-SOURCE() BABELTRACE2-SOURCE()
babeltrace2-source.text.dmesg - Babeltrace 2: Linux kernel ring
buffer source component class
A Babeltrace 2 source.text.dmesg message iterator reads the lines
of a Linux kernel ring buffer, as printed by the dmesg(1) tool,
and emits corresponding event messages.
Linux kernel ring buffer
lines (file or standard input)
|
| +----------------+
| | src.text.dmesg |
'-->| |
| out @--> Messages (single stream)
+----------------+
See babeltrace2-intro(7) to learn more about the Babeltrace 2
project and its core concepts.
A source.text.dmesg message iterator names the events it creates
string. Each event contain a single payload string field named str
which contains the corresponding ring buffer line.
By default, a source.text.dmesg message iterator reads the lines
of the standard input stream. You can make the message iterator
read the lines of a text file instead with the path parameter.
By default, the message iterator tries to extract the timestamps
of the kernel ring buffer lines and use them as the timestamps of
the created events. A typical dmesg(1) line looks like this:
[87166.510937] PM: Finishing wakeup.
The [87166.510937] part is the timestamp to extract. When this
information is available, the component creates a clock class
which does NOT have the Unix epoch as its origin.
You can make the message iterator not extract timestamps from
lines with the no-extract-timestamp parameter.
Note
It’s possible that the output of dmesg(1) contains unsorted
lines, that is, their timestamps go back in time. You can see
this with the --show-delta option of dmesg(1): some time
differences can be negative.
This is due to a 2019 change (see
<https://lwn.net/Articles/780556/>) to the API of the kernel
ring buffer.
As of this version, a source.text.dmesg message iterator
requires that the input kernel ring buffer lines be sorted by
timestamp (when they have timestamps), failing otherwise.
no-extract-timestamp=VAL [optional boolean]
If VAL is true, then do NOT extract timestamps from the kernel
ring buffer lines: set the str payload field of the created
event to the whole line, including any timestamp prefix.
Default: false.
path=PATH [optional string]
Read the kernel ring buffer lines from the file PATH instead
of the standard input stream.
+----------------+
| src.text.dmesg |
| |
| out @
+----------------+
Output
out
Single output port.
If you encounter any issue or usability problem, please report it
on the Babeltrace bug tracker (see
<https://bugs.lttng.org/projects/babeltrace>).
The Babeltrace project shares some communication channels with the
LTTng project (see <https://lttng.org/>).
• Babeltrace website (see <https://babeltrace.org/>)
• Mailing list (see <https://lists.lttng.org>) for support and
development: lttng-dev@lists.lttng.org
• IRC channel (see <irc://irc.oftc.net/lttng>): #lttng on
irc.oftc.net
• Bug tracker (see <https://bugs.lttng.org/projects/babeltrace>)
• Git repository (see
<https://git.efficios.com/?p=babeltrace.git>)
• GitHub project (see <https://github.com/efficios/babeltrace>)
• Continuous integration (see
<https://ci.lttng.org/view/Babeltrace/>)
• Code review (see
<https://review.lttng.org/q/project:babeltrace>)
The Babeltrace 2 project is the result of hard work by many
regular developers and occasional contributors.
The current project maintainer is Jérémie Galarneau
<mailto:jeremie.galarneau@efficios.com>.
This component class is part of the Babeltrace 2 project.
Babeltrace is distributed under the MIT license (see
<https://opensource.org/licenses/MIT>).
babeltrace2-plugin-text(7), babeltrace2-intro(7)
This page is part of the babeltrace (trace read and write
libraries and a trace converter) project. Information about the
project can be found at ⟨http://www.efficios.com/babeltrace⟩. If
you have a bug report for this manual page, send it to
lttng-dev@lists.lttng.org. This page was obtained from the
project's upstream Git repository
⟨git://git.efficios.com/babeltrace.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-06-25.) 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
BABELTRACE2-SOURCE()
Pages that refer to this page: babeltrace2(1), babeltrace2-plugin-text(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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