lttng-rotate - Man Page

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:

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:

  • The selected recording session was created in normal mode or in network streaming mode (see lttng-create(1)).
  • No channel was created with a configured trace file count or size limit (see the --tracefile-size and --tracefile-count options of the lttng-enable-channel(1) command).
  • 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_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_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.

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

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)

Referenced By

babeltrace2-source.ctf.fs(7), lttng(1), lttng-add-trigger(1), lttng-concepts(7), lttng-create(1), lttng-disable-rotation(1), lttng-enable-rotation(1), lttng-stop(1).

14 June 2021 LTTng 2.13.0 LTTng Manual