`lttng-create` ( 1 )

создайте сеанс трассировки LTTng (Create an LTTng tracing session)

Имя (Name)

lttng-create - Create an LTTng tracing session

Синопсис (Synopsis)

Local mode:

lttng [GENERAL OPTIONS] create [SESSION] [--shm-path=PATH] [--no-output | --output=PATH | --set-url=file://PATH]

Network streaming mode:

lttng [GENERAL OPTIONS] create [SESSION] [--shm-path=PATH] (--set-url=URL | --ctrl-url=URL --data-url=URL)

Snapshot mode:

lttng [GENERAL OPTIONS] create [SESSION] --snapshot [--shm-path=PATH] [--set-url=URL | --ctrl-url=URL --data-url=URL]

Live mode:

lttng [GENERAL OPTIONS] create [SESSION] --live[=DELAYUS] [--shm-path=PATH] [--set-url=URL | --ctrl-url=URL --data-url=URL]

Описание (Description)

The lttng create command creates a new tracing session.

A tracing session is a named container of channels, which in turn contain event rules. It is domain-agnostic, in that channels and event rules can be enabled for the user space tracer and/or the Linux kernel tracer.

On execution, an .lttngrc file is created, if it does not exist, in the user's home directory. This file contains the name of the current tracing session. When creating a new tracing session with lttng create, the current tracing session is set to this new tracing session. The lttng-set-session(1) command can be used to set the current tracing session without manually editing the .lttngrc file.

If SESSION is omitted, a session name is automatically created having this form: auto-YYYYmmdd-HHMMSS. SESSION must not contain the character /.

The --shm-path option can be used to specify the path to the shared memory holding the ring buffers. Specifying a location on an NVRAM file system makes it possible to retrieve the latest recorded trace data when the system reboots after a crash. To view the events of ring buffer files after a system crash, use the lttng-crash(1) utility.

Tracing sessions are destroyed using the lttng-destroy(1) command.

Creation modes There are four tracing session modes:

Local mode Traces the local system and writes the trace to the local file system. The --output option specifies the trace path. Using --set-url=file://PATH is the equivalent of using --output=PATH. The file system output can be disabled using the --no-output option.

If none of the options mentioned above are used, then the trace is written locally in the $LTTNG_HOME/lttng-traces directory ($LTTNG_HOME defaults to $HOME).

Network streaming mode Traces the local system and sends the trace over the network to a listening relay daemon (see lttng-relayd(8)). The --set- url, or --ctrl-url and --data-url options set the trace output destination (see the URL format section below).

Snapshot mode Traces the local system without writing the trace to the local file system (implicit --no-output option). Channels are automatically configured to be snapshot-ready on creation (see lttng-enable-channel(1)). The lttng-snapshot(1) command is used to take snapshots of the current ring buffers. The --set-url, or --ctrl-url and --data-url options set the default snapshot output destination.

Live mode Traces the local system, sending trace data to an LTTng relay daemon over the network (see lttng-relayd(8)). The --set-url, or --ctrl-url and --data-url options set the trace output destination. The live output URLs cannot use the file:// protocol (see the URL format section below).

URL format The --set-url, --ctrl-url, and --data-url options' arguments are URLs.

The format of those URLs is one of:

file://TRACEPATH NETPROTO://(HOST | IPADDR)[:CTRLPORT[:DATAPORT]][/TRACEPATH]

The file:// protocol targets the local file system and can only be used as the --set-url option's argument when the session is created in local or snapshot mode.

TRACEPATH Absolute path to trace files on the local file system.

The other version is available when the session is created in network streaming, snapshot, or live mode.

NETPROTO Network protocol, amongst:

net TCP over IPv4; the default values of CTRLPORT and DATAPORT are respectively 5342 and 5343.

net6 TCP over IPv6: same default ports as the net protocol.

tcp Same as the net protocol; can only be used with the --ctrl-url and --data-url options together.

tcp6 Same as the net6 protocol; can only be used with the --ctrl-url and --data-url options together.

(HOST | IPADDR) Hostname or IP address (IPv6 address must be enclosed in brackets ([ and ]); see RFC 2732 <https://www.ietf.org/rfc/rfc2732.txt>).

CTRLPORT Control port.

DATAPORT Data port.

TRACEPATH Path of trace files on the remote file system. This path is relative to the base output directory set on the relay daemon side; see lttng-relayd(8).

Параметры (Options)

General options are described in lttng(1).

   Mode selection
       --live[=DELAYUS]
           Create the session in live mode.

           The optional DELAYUS parameter, given in microseconds, is the
           maximum time the user can wait for the data to be flushed.
           This mode can be set with a network URL (options --set-url,
           or --ctrl-url and --data-url) and must have a relay daemon
           listening (see lttng-relayd(8)).

           By default, DELAYUS is 1000000 and the network URL is set to
           net://127.0.0.1.

       --snapshot
           Create the session in snapshot mode. This is the equivalent
           of using the --no-output option and creating all the channels
           of this new tracing session in overwrite mode with an mmap
           output type.

   Output
       --no-output
           In local mode, do not output any trace data.

       -o PATH, --output=PATH
           In local mode, set trace output path to PATH.

       --shm-path=PATH
           Create shared memory holding buffers at PATH.

   URL
       See the URL format section above for more information about the
       syntax of the following options' URL argument.

       -C URL, --ctrl-url=URL
           Set control path URL to URL (must use --data-url option
           also).

       -D URL, --data-url=URL
           Set data path URL to URL (must use --ctrl-url option also).

       -U URL, --set-url=URL
           Set URL destination of the trace data to URL. It is
           persistent for the session lifetime. This option sets both
           data (--data-url option) and control (--ctrl-url option) URLs
           at the same time.

           In local mode, URL must start with file:// followed by the
           destination path on the local file system.

   Program information
       -h, --help
           Show command help.

           This option, like lttng-help(1), attempts to launch
           /usr/bin/man to view the command's man page. The path to the
           man pager can be overridden by the LTTNG_MAN_BIN_PATH
           environment variable.

       --list-options
           List available command options.

Переменные окружения (Environment variables)

LTTNG_ABORT_ON_ERROR Set to 1 to abort the process after the first error is encountered.

LTTNG_HOME Overrides the $HOME environment variable. Useful when the user running the commands has a non-writable home directory.

LTTNG_MAN_BIN_PATH Absolute path to the man pager to use for viewing help information about LTTng commands (using lttng-help(1) or lttng COMMAND --help).

LTTNG_SESSION_CONFIG_XSD_PATH Path in which the session.xsd session configuration XML schema may be found.

LTTNG_SESSIOND_PATH Full session daemon binary path.

The --sessiond-path option has precedence over this environment variable.

Note that the lttng-create(1) command can spawn an LTTng session daemon automatically if none is running. See lttng-sessiond(8) for the environment variables influencing the execution of the session daemon.

Файлы (Files)

$LTTNG_HOME/.lttngrc User LTTng runtime configuration.

This is where the per-user current tracing session is stored between executions of lttng(1). The current tracing session can be set with lttng-set-session(1). See lttng-create(1) for more information about tracing sessions.

$LTTNG_HOME/lttng-traces Default output directory of LTTng traces. This can be overridden with the --output option of the lttng-create(1) command.

$LTTNG_HOME/.lttng User LTTng runtime and configuration directory.

$LTTNG_HOME/.lttng/sessions Default location of saved user tracing sessions (see lttng-save(1) and lttng-load(1)).

/usr/local/etc/lttng/sessions System-wide location of saved tracing sessions (see lttng-save(1) and lttng-load(1)).

Note $LTTNG_HOME defaults to $HOME when not explicitly set.

Статус выхода (Exit)

0 Success

1 Command error

2 Undefined command

3 Fatal error

4 Command warning (something went wrong during the command)

Ошибки (баги) (Bugs)

If you encounter any issue or usability problem, please report it on the LTTng bug tracker <https://bugs.lttng.org/projects/lttng- tools>.

Ресурсы (Resources)

• LTTng project website <https://lttng.org>

• LTTng documentation <https://lttng.org/docs>

• Git repositories <http://git.lttng.org>

• GitHub organization <http://github.com/lttng>

• Continuous integration <http://ci.lttng.org/>

• Mailing list <http://lists.lttng.org> for support and development: lttng-dev@lists.lttng.org

• IRC channel <irc://irc.oftc.net/lttng>: #lttng on irc.oftc.net

Исходный текст на man7.org

lttng-create ( 1 )