LTTNG-ROTATE(1)

NAME
lttng-rotate - Archive the current trace chunk of an LTTng recording session

SYNOPSIS

lttng [GENERAL OPTIONS] rotate [--no-wait] [SESSION]

DESCRIPTION

The lttng rotate command archives to the file system the current trace chunk of:

With the SESSION argument
    The recording session named SESSION.

Without the SESSION argument
    The current recording session (see lttng-concepts(7) to learn more about the current recording session).

This action is called a recording session rotation.

See lttng-concepts(7) to learn more about the recording session rotation and trace chunk concepts.

You can use the rotate command:

    • Any time the recording session is active.

    • A single time once the recording session becomes inactive.

See lttng-concepts(7) to learn more about the activity of a recording session.

By default, the rotate command ensures that LTTng finished performing the recording session rotation before it prints the path of the archived trace chunk and exits. The printed path is absolute when the recording session was created in normal mode and relative to the base output directory of the relay daemon (see the --output option of lttng-relayd(8)) when it was created in network streaming mode (see lttng-create(1)).

Make the command exit immediately with the --no-wait option. In this case, there’s no easy way to know when the current trace chunk becomes archived, and the command does NOT print the path of the archived trace chunk.

Because LTTng flushes the current sub-buffers of the selected recording session when it performs a recording session rotation, archived trace chunks are never redundant, that is, they do not overlap over time like snapshots can (see lttng-snapshot(1)). Also, a rotation does NOT directly cause discarded event records or packets.

A rotate-session trigger action can also rotate a recording session (see lttng-add-trigger(1)).

See the “EXAMPLES” section below for usage examples.

Important

    You may only use the rotate command when all of the following conditions are true:

        • The selected recording session was created in normal mode or in network streaming mode (see lttng-create(1)).

        • LTTng is not currently performing an immediate rotation (this command).

OPTIONS

See lttng(1) for GENERAL OPTIONS.

-n, --no-wait
    Do not ensure that the recording session rotation operation is completed before exiting.

  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. Rotate the current recording session.

        $ lttng rotate

Example 2. Rotate a specific recording session.

        $ lttng rotate my-session

Example 3. Rotate the current recording session without waiting for completion.

    See the --no-wait option.

        $ lttng rotate --no-wait

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.

SEE ALSO

lttng(1), lttng-disable-rotation(1), lttng-enable-rotation(1), lttng-concepts(7)