lttng-view - Man Page
Launch an LTTng trace reader
Synopsis
lttng [GENERAL OPTIONS] view [--viewer=READER]
[SESSION | --trace-path=DIR]Description
The lttng view command launches an external trace reader to read the current traces of:
- With the SESSION argument
The recording session named SESSION.
- With the --trace-path=DIR option
The local file system directory DIR.
- Otherwise
The current recording session (see concepts(1) to learn more about the current recording session).
With the SESSION argument or without the --trace-path option, the mode of the selected recording session may NOT be network streaming or live.
By default, the view command attempts to launch babeltrace2(1) or, if it’s not available, babeltrace(1). Override which trace reader to launch with the --viewer option.
See the “Examples” section below for usage examples.
Options
See lttng(1) for GENERAL OPTIONS.
- -t DIR, --trace-path=DIR
Pass DIR as the last argument of the trace reader command instead of the output directory of the selected recording session.
- -e READER, --viewer=READER
Use the trace reader READER to read the traces.
READER is the absolute path to the reader command to use, and it can contain command arguments as well. The view command passes the trace directory path to read to the READER command as its last argument.
Without this option, the view command uses babeltrace2(1) if it’s available. Otherwise, it tries to use babeltrace(1).
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.
Exit Status
- 0
Success
- 1
Command error
- 2
Undefined command
- 3
Fatal error
- 4
Command warning (something went wrong during the command)
Environment
- 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.
Files
- $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.
Examples
Example 1. Read the traces of the current recording session with Babeltrace.
$ lttng view
Example 2. Read the traces of a specific recording session with a custom trace reader.
Resources
- 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>
Copyright
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.
Thanks
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.