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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | ENVIRONMENT VARIABLES | FILES | EXIT STATUS | BUGS | RESOURCES | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON |
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BABELTRACE2-QUERY(1) Babeltrace 2 manual BABELTRACE2-QUERY(1)
babeltrace2-query - Query an object from a Babeltrace 2 component
class
babeltrace2 [GENERAL OPTIONS] query [--params=PARAMS]
COMP-CLS-TYPE.PLUGIN-NAME.COMP-CLS-NAME OBJECT
The query command queries the object named OBJECT from the
component class named COMP-CLS-NAME of the type COMP-CLS-TYPE
found in the Babeltrace 2 plugin named PLUGIN-NAME and prints the
results.
See babeltrace2-intro(7) to learn more about the Babeltrace 2
project and its core concepts.
The available values for COMP-CLS-TYPE are:
source, src
Source component class.
filter, flt
Filter component class.
sink
Sink component class.
The exact object names and the parameters that a given component
class expects are described in its own documentation.
babeltrace2-help(1) can generally provide this information.
You can use the --params option to pass parameters to the query
operation of the component class.
The output of the query command can look like YAML (see
<https://yaml.org/>), but it’s not guaranteed to be
YAML-compliant.
See “EXAMPLES” for usage examples.
General
You can use those options before the command name.
See babeltrace2(1) for more details.
-d, --debug
Legacy option: this is equivalent to --log-level=TRACE.
-l LVL, --log-level=LVL
Set the log level of all known Babeltrace 2 loggers to LVL.
--omit-home-plugin-path
Don’t search for plugins in
$HOME/.local/lib/babeltrace2/plugins.
--omit-system-plugin-path
Don’t search for plugins in
/usr/local/lib/babeltrace2/plugins.
--plugin-path=PATH[:PATH]...
Add PATH to the list of paths in which plugins can be found.
-v, --verbose
Legacy option: this is equivalent to --log-level=INFO.
Query parameters
-p PARAMS, --params=PARAMS
Set the query parameters to PARAMS.
The format of PARAMS is a comma-separated list of NAME=VALUE
assignments:
NAME=VALUE[,NAME=VALUE]...
NAME
Parameter name (C identifier plus the :, ., and -
characters).
VALUE
One of:
• null, nul, NULL: null value.
• true, TRUE, yes, YES: true boolean value.
• false, FALSE, no, NO: false boolean value.
• Binary (0b prefix), octal (0 prefix), decimal, or
hexadecimal (0x prefix) unsigned (with + prefix) or
signed 64-bit integer.
• Double precision floating point number (scientific
notation is accepted).
• Unquoted string with no special characters, and not
matching any of the null and boolean value symbols
above.
• Double-quoted string (accepts escape characters).
• Array, formatted as an opening [, a comma-separated
list of VALUE, and a closing ].
• Map, formatted as an opening {, a comma-separated list
of NAME=VALUE assignments, and a closing }.
You may put whitespaces around the individual =
(assignment), , (separator), [ (array beginning), ] (array
end), { (map beginning), and } (map end) characters.
Example:
--params='many=null, fresh=yes, condition=false, squirrel=-782329,
play=+23, observe=3.14, simple=beef,
needs-quotes="some string",
escape.chars-are:allowed="a \" quote",
things=[1, "hello", 2.71828],
frog={slow=2, bath=[bike, 23], blind=NO}'
Important
Like in the example above, make sure to single-quote the
whole argument when you run this command from a shell, as
it can contain many special characters.
Command information
-h, --help
Show the command help and quit.
Example 1. Query the available tracing sessions of a local LTTng
relay daemon.
$ babeltrace2 query src.ctf.lttng-live sessions \
--params='url="net://localhost"'
Example 2. Query the metadata info (includes the decoded plain
text) of a CTF trace located on the local file system.
$ babeltrace2 query src.ctf.fs metadata-info \
--params='inputs=["/path/to/trace"]'
Example 3. Query the trace infos of a CTF trace located on the
local file system.
$ babeltrace2 query src.ctf.fs babeltrace.trace-infos \
--params='inputs=["/path/to/trace"]'
Example 4. Query some object from a sink component class without
parameters.
$ babeltrace2 query sink.my-plugin.my-sink some-object
Babeltrace 2 library
BABELTRACE_EXEC_ON_ABORT=CMDLINE
Execute the command line CMDLINE, as parsed like a UNIX 98
shell, when any part of the Babeltrace 2 project unexpectedly
aborts.
The application only aborts when the executed command returns,
ignoring its exit status.
This environment variable is ignored when the application has
the setuid or the setgid access right flag set.
BABELTRACE_TERM_COLOR=(AUTO | NEVER | ALWAYS)
Force the terminal color support for the babeltrace2(1)
program and the project plugins.
The available values are:
AUTO
Only emit terminal color codes when the standard output
and error streams are connected to a color-capable
terminal.
NEVER
Never emit terminal color codes.
ALWAYS
Always emit terminal color codes.
BABELTRACE_TERM_COLOR_BRIGHT_MEANS_BOLD=0
Set to 0 to emit SGR (see
<https://en.wikipedia.org/wiki/ANSI_escape_code>) codes 90
to 97 for bright colors instead of bold (SGR code 1) and
standard color codes (SGR codes 30 to 37).
BABELTRACE_PLUGIN_PATH=PATHS
Set the list of directories, in order, in which dynamic
plugins can be found before other directories are considered
to PATHS (colon-separated, or semicolon on Windows).
LIBBABELTRACE2_DISABLE_PYTHON_PLUGINS=1
Disable the loading of any Babeltrace 2 Python plugin.
LIBBABELTRACE2_INIT_LOG_LEVEL=LVL
Force the initial log level of the Babeltrace 2 library to be
LVL.
If this environment variable is set, then it overrides the log
level set by the --log-level option for the Babeltrace 2
library logger.
The available values for LVL are:
NONE, N
Logging is disabled.
FATAL, F
Severe errors that lead the execution to abort
immediately.
This level should be enabled in production.
ERROR, E
Errors that might still allow the execution to continue.
Usually, once one or more errors are reported at this
level, the application, plugin, or library won’t perform
any more useful task, but it should still exit cleanly.
This level should be enabled in production.
WARN, WARNING, W
Unexpected situations which still allow the execution to
continue.
This level should be enabled in production.
INFO, I
Informational messages that highlight progress or
important states of the application, plugins, or library.
This level can be enabled in production.
DEBUG, D
Debugging information, with a higher level of details than
the TRACE level.
This level should NOT be enabled in production.
TRACE, T
Low-level debugging context information.
This level should NOT be enabled in production.
LIBBABELTRACE2_NO_DLCLOSE=1
Make the Babeltrace 2 library leave any dynamically loaded
modules (plugins and plugin providers) open at exit. This can
be useful for debugging purposes.
LIBBABELTRACE2_PLUGIN_PROVIDER_DIR=DIR
Set the directory from which the Babeltrace 2 library
dynamically loads plugin provider shared objects to DIR.
If this environment variable is set, then it overrides the
default plugin provider directory.
Babeltrace 2 Python bindings
BABELTRACE_PYTHON_BT2_LOG_LEVEL=LVL
Force the Babeltrace 2 Python bindings log level to be LVL.
If this environment variable is set, then it overrides the log
level set by the --log-level option for the Python bindings
logger.
The available values for LVL are:
NONE, N
Logging is disabled.
FATAL, F
Severe errors that lead the execution to abort
immediately.
This level should be enabled in production.
ERROR, E
Errors that might still allow the execution to continue.
Usually, once one or more errors are reported at this
level, the application, plugin, or library won’t perform
any more useful task, but it should still exit cleanly.
This level should be enabled in production.
WARN, WARNING, W
Unexpected situations which still allow the execution to
continue.
This level should be enabled in production.
INFO, I
Informational messages that highlight progress or
important states of the application, plugins, or library.
This level can be enabled in production.
DEBUG, D
Debugging information, with a higher level of details than
the TRACE level.
This level should NOT be enabled in production.
TRACE, T
Low-level debugging context information.
This level should NOT be enabled in production.
CLI
BABELTRACE_CLI_LOG_LEVEL=LVL
Force the log level of the log level babeltrace2 CLI to be
LVL.
If this environment variable is set, then it overrides the log
level set by the --log-level option for the CLI logger.
The available values for LVL are:
NONE, N
Logging is disabled.
FATAL, F
Severe errors that lead the execution to abort
immediately.
This level should be enabled in production.
ERROR, E
Errors that might still allow the execution to continue.
Usually, once one or more errors are reported at this
level, the application, plugin, or library won’t perform
any more useful task, but it should still exit cleanly.
This level should be enabled in production.
WARN, WARNING, W
Unexpected situations which still allow the execution to
continue.
This level should be enabled in production.
INFO, I
Informational messages that highlight progress or
important states of the application, plugins, or library.
This level can be enabled in production.
DEBUG, D
Debugging information, with a higher level of details than
the TRACE level.
This level should NOT be enabled in production.
TRACE, T
Low-level debugging context information.
This level should NOT be enabled in production.
BABELTRACE_CLI_WARN_COMMAND_NAME_DIRECTORY_CLASH=0
Disable the warning message which babeltrace2-convert(1)
prints when you convert a trace with a relative path that’s
also the name of a babeltrace2 command.
BABELTRACE_DEBUG=1
Legacy variable: equivalent to setting the --log-level option
to TRACE.
BABELTRACE_VERBOSE=1
Legacy variable: equivalent to setting the --log-level option
to INFO.
$HOME/.local/lib/babeltrace2/plugins
User plugin directory.
/usr/local/lib/babeltrace2/plugins
System plugin directory.
/usr/local/lib/babeltrace2/plugin-providers
System plugin provider directory.
0 on success, 1 otherwise.
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 command is part of the Babeltrace 2 project.
Babeltrace is distributed under the MIT license (see
<https://opensource.org/licenses/MIT>).
babeltrace2-intro(7), babeltrace2(1)
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
Babeltrace 2.2.0rc1 14 September 2019 BABELTRACE2-QUERY(1)
Pages that refer to this page: babeltrace2(1), babeltrace2-intro(7), babeltrace2-query-babeltrace.support-info(7), babeltrace2-query-babeltrace.trace-infos(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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