$
lttng save
lttng-save — Save LTTng recording session configurations
lttng [GENERAL OPTIONS] save [--force] [--output-path=DIR] [--no-triggers] [--all|SESSION]
The lttng save command saves to files the configurations of:
SESSION argument
The recording session named SESSION.
SESSION argument
Implicit --all option: all the recording sessions of the
connected session daemon for your Unix user, or for all users if
your Unix user is root, as listed in the output of lttng list
(see lttng-list(1)).
See the “Session daemon connection” section of lttng(1) to learn how a user application connects to a session daemon.
See lttng-concepts(7) to learn more about recording sessions.
Use the save command in conjunction with the lttng-load(1) command
to save and restore the complete configurations of recording sessions.
The save command does not save tracing data, only the recording
session parameters, including the event record channel and recording
event rule configurations.
Each saved recording session configuration file also contains all the
triggers (see lttng-add-trigger(1)) of the connected session daemon
for your Unix user, or for all users if your Unix user is root, even
those triggers which aren’t directly related to the targeted recording
session(s). This is needed because, for example, an “increment map
value” trigger action targets a map channel of a specific recording
session, but the trigger itself is a session daemon-wide object.
The lttng-load(1) command makes the loading Unix user the owner of every loaded recording session and trigger, regardless of their original owner.
Avoid saving any trigger with the --no-triggers option. Note,
however, that without saved triggers, the lttng-load(1) command
won’t restore, amongst other things, the “increment map value” actions
for the loaded recording session(s).
The default output directory path is $LTTNG_HOME/.lttng/sessions
($LTTNG_HOME defaults to $HOME). Override the default output
directory path with the --output-path option. Each recording
session configuration file is named SNAME.lttng,
where SNAME is the original recording session name.
By default, the save command does not overwrite existing recording
session configuration files: the command fails. Allow the save command
to overwrite existing recording session configuration files with the
--force option.
See the “EXAMPLES” section below for usage examples.
See lttng(1) for GENERAL OPTIONS.
-a, --all
Save all the recording session configurations of your Unix user, or
of all users if your Unix user is root, as listed in the output of
lttng-list(1), instead of the current recording session or the
recording session named SESSION.
-f, --force
Overwrite existing recording session configuration files when saving.
--no-triggers
Do not save any trigger (see lttng-add-trigger(1)).
This is the behaviour of LTTng ≤ 2.15.
Without this option, each saved recording session configuration file
also contains all the triggers of the connected session daemon for your
Unix user, or for all users if your Unix user is root, even those
triggers which aren’t directly related to the targeted recording
session(s).
With this option, the lttng-load(1) command won’t restore, amongst other things, the “increment map value” actions of the loaded recording session(s).
-o DIR, --output-path=DIR
Save recording session configuration files to the directory DIR
instead of $LTTNG_HOME/.lttng/sessions ($LTTNG_HOME defaults to
$HOME).
-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.
Success
Command error
Undefined command
Fatal error
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 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.
$LTTNG_HOME/.lttng/sessions
Default directory containing the Unix user’s saved recording session configurations (see lttng-save(1) and lttng-load(1)).
/etc/lttng/sessions
Directory containing the system-wide saved recording session configurations (see lttng-save(1) and lttng-load(1)).
Note:$LTTNG_HOME defaults to the value of the HOME environment
variable.
Example:Save all the recording session configurations to the default output directory.
$
lttng save
Example:Save a specific recording session configuration to a specific output directory.
See the --output-path option.
$
lttng save my-session --output-path=/path/to/sessions
Example:Allow LTTng to overwrite existing recording session configuration files when saving.
See the --force option.
$
lttng save --force
Example:Save the configuration of a specific recording session without saving any trigger.
See the --no-triggers option.
$
lttng save my-session --no-triggers
Mailing list for support and
development: lttng-dev@lists.lttng.org
IRC channel: #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. See the
LICENSE file
for details.
Special thanks to Michel Dagenais and the DORSAL laboratory 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.