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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT VARIABLES | FILES | EXIT STATUS | LIMITATIONS | BUGS | RESOURCES | COPYRIGHTS | THANKS | AUTHORS | SEE ALSO | COLOPHON |
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LTTNG-RELAYD(8) LTTng Manual LTTNG-RELAYD(8)
lttng-relayd - LTTng 2 relay daemon
lttng-relayd [--background | --daemonize]
[--control-port=URL] [--data-port=URL] [--live-port=URL]
[--output=PATH] [-v | -vv | -vvv]
The Linux Trace Toolkit: next generation <https://lttng.org/> is
an open source software package used for correlated tracing of the
Linux kernel, user applications, and user libraries.
LTTng consists of Linux kernel modules (for Linux kernel tracing)
and dynamically loaded libraries (for user application and library
tracing).
The LTTng relay daemon is responsible for receiving trace data
from possibly remote LTTng session/consumer daemons and for
writing it to the local file system. The relay daemon also accepts
LTTng live connections from compatible viewers; this is the
official approach to viewing LTTng events as they are emitted.
The relay daemon listens by default on all network interfaces to
gather trace data, but only on localhost for LTTng live
connections.
The relay daemon does not require any particular permissions, as
long as it can write to the output directory and listen on the
configured ports. If a user is within a secured network and/or has
proper firewall settings, lttng-relayd can listen to LTTng live
connections from all network interfaces by specifying --live-
port=tcp://localhost:5344.
Once a trace has been streamed completely, the trace can be
processed by any tool that can process an LTTng trace located on
the local file system.
Output directory
By default, the relay daemon writes the traces to:
$LTTNG_HOME/lttng-traces/HOSTNAME/SESSION/DOMAIN
with:
HOSTNAME
Remote hostname.
SESSION
Full session name.
DOMAIN
Tracing domain.
You can override the default output directory prefix
($LTTNG_HOME/lttng-traces) with the --output option. The other
parts depend on the remote configuration.
URL format
The --control-port, --data-port, and --live-port options specify
URLs.
The format of those URLs is:
tcp://(HOST | IPADDR):PORT
with:
(HOST | IPADDR)
Binding hostname or IP address (IPv6 address must be enclosed
in brackets ([ and ]); see RFC 2732
<https://www.ietf.org/rfc/rfc2732.txt>).
PORT
TCP port.
Daemon
-b, --background
Start as Unix daemon, but keep file descriptors (console)
open. Use the --daemonize option instead to close the file
descriptors.
-d, --daemonize
Start as Unix daemon, and close file descriptors (console).
Use the --background option instead to keep the file
descriptors open.
-g GROUP, --group=GROUP
Use GROUP as Unix tracing group (default: tracing).
-o PATH, --output=PATH
Set base directory of written trace data to PATH.
See the Output directory section above for more information.
-v, --verbose
Increase verbosity.
Three levels of verbosity are available, which are triggered
by appending additional v letters to the option (that is, -vv
and -vvv).
Ports
See the URL format section above for more information about the
syntax of the following options' URL argument.
-C URL, --control-port=URL
Listen to control data on URL URL (default:
tcp://0.0.0.0:5342).
-D URL, --data-port=URL
Listen to trace data on URL URL (default: tcp://0.0.0.0:5343).
-L URL, --live-port=URL
Listen to LTTng live connections on URL URL (default:
tcp://localhost:5344).
Program information
-h, --help
Show help.
-V, --version
Show version.
LTTNG_ABORT_ON_ERROR
Set to 1 to abort the process after the first error is
encountered.
LTTNG_NETWORK_SOCKET_TIMEOUT
Socket connection, receive and send timeout (milliseconds). A
value of 0 or -1 uses the timeout of the operating system
(default).
LTTNG_RELAYD_HEALTH
Path to relay daemon health’s socket.
LTTNG_RELAYD_TCP_KEEP_ALIVE
Set to 1 to enable TCP keep-alive.
The TCP keep-alive mechanism allows the detection of dead
peers (lttng-sessiond(8)) in cases of unclean termination (for
example, a hard reset) of a peer.
Supported on Linux and Solaris only. The default behaviour of
the TCP keep-alive mechanism is OS-specific.
Search for tcp_keepalive in tcp(7) for more information.
LTTNG_RELAYD_TCP_KEEP_ALIVE_ABORT_THRESHOLD
The time threshold in seconds to abort a TCP connection after
the keep-alive probing mechanism has failed.
Set to 0 or -1 to use the value chosen by the operating system
(default).
Supported on Solaris 11 only.
Search for tcp_keepalive_abort_threshold in tcp(7) for more
information.
LTTNG_RELAYD_TCP_KEEP_ALIVE_IDLE_TIME
Number of seconds a connection needs to be idle before TCP
begins sending out keep-alive probes.
Set to 0 or -1 to use the value chosen by the operating system
(default).
Supported on Linux and Solaris 11 only.
On Solaris 11, the accepted values are -1, 0, and 10 to
864000.
Search for tcp_keepalive_time and tcp_keepalive_interval in
tcp(7) on Solaris 11 for more information.
LTTNG_RELAYD_TCP_KEEP_ALIVE_MAX_PROBE_COUNT
Maximum number of TCP keep-alive probes to send before giving
up and killing the connection if no response is obtained from
the other end.
Set to 0 or -1 to use the value chosen by the operating system
(default).
Supported on Linux only.
Search for tcp_keepalive_probes in tcp(7) for more
information.
LTTNG_RELAYD_TCP_KEEP_ALIVE_PROBE_INTERVAL
Number of seconds between TCP keep-alive probes.
Set to 0 or -1 to use the value chosen by the operating system
(default).
Supported on Linux only.
Search for tcp_keepalive_intvl in tcp(7) for more information.
$LTTNG_HOME/.lttng
User LTTng runtime and configuration directory.
$LTTNG_HOME/lttng-traces
Default output directory of LTTng traces. This can be
overridden with the --output option.
Note
$LTTNG_HOME defaults to $HOME when not explicitly set.
0
Success
1
Error
3
Fatal error
As of this version, only the TCP protocol is supported for both
control and data ports. In future versions, TCP will remain the
sole available protocol for control data since those
communications are low-volume and need absolute reliability; trace
data could be carried over UDP.
For an unprivileged user running lttng-relayd, the maximum number
of file descriptors per process is usually 1024. This limits the
number of connections and opened trace files. This limit can be
configured with ulimit(3).
If you encounter any issue or usability problem, please report it
on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng-
tools>.
• LTTng project website <https://lttng.org>
• LTTng documentation <https://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: [email protected]
• IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
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-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:[email protected]>.
lttng(1), lttng-sessiond(8), lttng-crash(1), lttng-ust(3),
babeltrace(1)
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 [email protected]. This page was obtained
from the project's upstream Git repository
⟨git://git.lttng.org/lttng-tools.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
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
[email protected]
LTTng 2.12.0-pre 10/29/2018 LTTNG-RELAYD(8)
Pages that refer to this page: lttng(1), lttng-crash(1), lttng-create(1), lttng-rotate(1), babeltrace2-source.ctf.lttng-live(7), lttng-sessiond(8)
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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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