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HTML rendering created 2026-09-09 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 | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | ENVIRONMENT | FILES | EXAMPLES | RESOURCES | COPYRIGHT | THANKS | SEE ALSO | COLOPHON |
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LTTNG-TRACK(1) LTTng Manual LTTNG-TRACK(1)
lttng-track - Allow specific processes to record LTTng events
Allow specific processes to record Linux kernel events:
lttng [GENERAL OPTIONS] track --kernel [--session=SESSION]
(--pid=PID[,PID]... | --vpid=VPID[,VPID]... |
--uid=UID[,UID]... | --vuid=VUSER[,VUSER]... |
--gid=GID[,GID]... | --vgid=VGROUP[,VGROUP]...)...
lttng [GENERAL OPTIONS] track --kernel [--session=SESSION]
--all (--pid | --vpid | --uid | --vuid | --gid | --vgid)...
Allow specific processes to record user space events:
lttng [GENERAL OPTIONS] track --userspace [--session=SESSION]
(--vpid=VPID[,VPID]... | --vuid=VUSER[,VUSER]... |
--vgid=VGROUP[,VGROUP]...)...
lttng [GENERAL OPTIONS] track --userspace [--session=SESSION]
--all (--vpid | --vgid | --vuid)...
The lttng track command allows one or more processes to record
LTTng events based on their attributes within:
With the --session=SESSION option
The recording session named SESSION.
Without the --session option
The current recording session (see lttng-concepts(7) to learn
more about the current recording session).
See lttng-concepts(7) to learn more about recording sessions and
recording event rules.
The track command adds values to inclusion sets of process
attributes. The available inclusion sets are, for a given
recording session:
With the --kernel option
• Process ID (PID).
• Virtual process ID (VPID).
This is the PID as seen by the application.
• Unix user ID (UID).
• Virtual Unix user ID (VUID).
This is the UID as seen by the application.
• Unix group ID (GID).
• Virtual Unix group ID (VGID).
This is the GID as seen by the application.
With the --userspace option
• VPID
• VUID
• VGID
When an event E satisfies all the other explicit and implicit
conditions of an event rule ER, ER matches E if the attributes of
the process for which LTTng creates E are all part of the
inclusion sets of the recording session and domain of ER.
By default, on recording session creation (see lttng-create(1)),
all processes are allowed to record events. In other words, all
the inclusion sets of the recording session contain all the
possible process attribute values.
If a given inclusion set IS contains all the possible values
(--all option), then using the track command to add one or more
values V to IS:
1. Removes all the values from IS.
This effectively makes IS empty.
2. Adds V to IS.
Example: with the PID inclusion set, you can record all the system
calls of a given process:
$ lttng enable-event --kernel --all --syscall
$ lttng track --kernel --pid=2345
$ lttng start
See the “EXAMPLES” section below for usage examples.
Remove values from an inclusion set with the lttng-untrack(1)
command.
Inclusion set example
This example operates on the Linux kernel process ID (PID)
inclusion set of the current recording session to show how an
inclusion set works.
Assume the maximum system PID is 7 for this example.
1. Initial inclusion set:
[0] [1] [2] [3] [4] [5] [6] [7]
2. Command:
$ lttng track --kernel --pid=3,6,7
Inclusion set is now:
[ ] [ ] [ ] [3] [ ] [ ] [6] [7]
3. Command:
$ lttng untrack --kernel --pid=7
Inclusion set is now:
[ ] [ ] [ ] [3] [ ] [ ] [6] [ ]
4. Command:
$ lttng track --kernel --pid=1,5
Inclusion set is now:
[ ] [1] [ ] [3] [ ] [5] [6] [ ]
Remove values from an inclusion set with the lttng-untrack(1)
command.
See lttng(1) for GENERAL OPTIONS.
Tracing domain
One of:
-k, --kernel
Add values to one or more Linux kernel inclusion sets.
-u, --userspace
Add values to one or more user space inclusion sets.
Recording target
-s SESSION, --session=SESSION
Add values to one or more inclusion sets of the recording
session named SESSION instead of the current recording
session.
Inclusion set selection
-p [PID[,PID]...], --pid[=PID[,PID]...]
For each PID argument, add PID to the process ID inclusion set
of the selected recording session and domain.
PID is the process ID attribute of a process as seen from the
root PID namespace (see pid_namespaces(7)).
Only available with --kernel option.
--vpid[=VPID[,VPID]...]
For each VPID argument, add VPID to the virtual process ID
inclusion set of the selected recording session and domain.
VPID is the virtual process ID attribute of a process as seen
from the PID namespace of the process (see pid_namespaces(7)).
--uid[=USER[,USER]...]
For each USER argument, add USER to the user ID inclusion set
of the selected recording session and domain.
USER is either:
• The real user ID (see getuid(3)) of a process as seen from
the root user namespace (see user_namespaces(7)).
• A user name.
The connected LTTng session daemon (see lttng-sessiond(8))
performs the user name resolution on addition to the user
ID inclusion set.
Only available with --kernel option.
--vuid[=VUSER[,VUSER]...]
For each VUSER argument, add VUSER to the virtual user ID
inclusion set of the selected recording session and domain.
VUSER is either:
• The real user ID (see getuid(3)) of a process as seen from
the user namespace (see user_namespaces(7)).
• A user name.
The connected LTTng session daemon (see lttng-sessiond(8))
performs the user name resolution on addition to the
virtual user ID inclusion set.
--gid[=GROUP[,GROUP]...]
For each GROUP argument, add GROUP to the group ID inclusion
set of the selected recording session and domain.
GROUP is either:
• The real group ID (see getgid(3)) of a process as seen
from the root user namespace (see user_namespaces(7)).
• A group name.
The connected LTTng session daemon (see lttng-sessiond(8))
performs the group name resolution on addition to the
group ID inclusion set.
Only available with --kernel option.
--vgid[=VGROUP[,VGROUP]...]
For each VGROUP argument, add VGROUP to the virtual group ID
inclusion set of the selected recording session and domain.
VGROUP is either:
• The real group ID (see getgid(3)) of a process as seen
from the user namespace (see user_namespaces(7)).
• A group name.
The connected LTTng session daemon (see lttng-sessiond(8))
performs the group name resolution on addition to the
virtual group ID inclusion set.
Inclusion set operation
-a, --all
With one or more empty --pid, --vpid, --uid, --vuid, --gid,
and --vgid options: add all the possible values to the
selected inclusion sets.
Program information
-h, --help
Show help.
This option attempts to launch /usr/bin/man to view this
manual page. Override the manual pager path with the
LTTNG_MAN_BIN_PATH environment variable.
--list-options
List available command options and quit.
0
Success
1
Command error
2
Undefined command
3
Fatal error
4
Command warning (something went wrong during the command)
LTTNG_ABORT_ON_ERROR
Set to 1 to abort the process after the first error is
encountered.
LTTNG_HOME
Path to the LTTng home directory.
Defaults to $HOME.
Useful when the Unix user running the commands has a
non-writable home directory.
LTTNG_LIST_LEGACY
Set to 1 to use the legacy output format (LTTng 2.14 and
earlier) for the lttng-list(1) command instead of the modern
output format.
Note that the legacy output doesn’t show anything related to
features introduced after LTTng 2.14.
LTTNG_MAN_BIN_PATH
Absolute path to the manual pager to use to read the LTTng
command-line help (with lttng-help(1) or with the --help
option) instead of /usr/bin/man.
LTTNG_NO_UTF_8
Set to 1 to NOT emit multi-byte UTF-8 sequences, even if the
locale claims to support it.
LTTNG_SESSION_CONFIG_XSD_PATH
Path to the directory containing the session.xsd recording
session configuration XML schema.
LTTNG_SESSIOND_PATH
Absolute path to the LTTng session daemon binary (see
lttng-sessiond(8)) to spawn from the lttng-create(1) command.
The --sessiond-path general option overrides this environment
variable.
LTTNG_TERM_COLOR
Controls when to emit terminal SGR codes in the output.
The NO_COLOR environment variable overrides this.
One of:
auto (default)
Only emit SGR codes when the standard output is connected
to a color-capable terminal.
always
Always emit SGR codes.
never
Never emit SGR codes.
NO_COLOR
If set and not empty, then it’s equivalent to setting
LTTNG_TERM_COLOR to never.
See NO_COLOR <https://no-color.org/> to learn more.
$LTTNG_HOME/.lttngrc
Unix user’s LTTng runtime configuration.
This is where LTTng stores the name of the Unix user’s current
recording session between executions of lttng(1).
lttng-create(1) and lttng-set-session(1) set the current
recording session.
$LTTNG_HOME/lttng-traces
Default output directory of LTTng traces in local and snapshot
modes.
Override this path with the --output option of the
lttng-create(1) command.
$LTTNG_HOME/.lttng
Unix user’s LTTng runtime and configuration directory.
$LTTNG_HOME/.lttng/sessions
Default directory containing the Unix user’s saved recording
session configurations (see lttng-save(1) and lttng-load(1)).
/usr/local/etc/lttng/sessions
Directory containing the system-wide saved recording session
configurations (see lttng-save(1) and lttng-load(1)).
Note
$LTTNG_HOME defaults to the value of the HOME environment
variable.
Example 1. Add the PIDs 1728 and 3775 to the Linux kernel process
ID inclusion set of the current recording session.
See the --pid option.
$ lttng track --kernel --pid=1728,3775
Example 2. Add the ID of a specific user to the user space virtual
user ID inclusion set of a specific recording session.
See the --vuid and --session options.
$ lttng track --userspace --session=my-session --vuid=http
Example 3. Add all the possible group IDs to the Linux kernel
group ID inclusion set of the current recording session.
See the --all and --gid options.
$ lttng track --kernel --all --gid
• LTTng project website <https://lttng.org>
• LTTng documentation <https://lttng.org/docs>
• LTTng bug tracker <https://bugs.lttng.org>
• Git repositories <https://git.lttng.org>
• GitHub organization <https://github.com/lttng>
• Continuous integration <https://ci.lttng.org/>
• Mailing list <https://lists.lttng.org/> for support and
development: lttng-dev@lists.lttng.org
• IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net
• Mastodon <https://mastodon.social/@lttng>
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(1), lttng-untrack(1), lttng-concepts(7)
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 man-pages@man7.org. This page was obtained
from the project's upstream Git repository
⟨https://github.com/lttng/lttng-tools.git⟩ on 2026-08-04. (At
that time, the date of the most recent commit that was found in
the repository was 2026-07-30.) 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
LTTng 2.15.1 14 June 2021 LTTNG-TRACK(1)
Pages that refer to this page: lttng(1), lttng-create(1), lttng-enable-event(1), lttng-untrack(1), lttng-concepts(7)
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HTML rendering created 2026-09-09 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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