lttng(1) ======== NAME ---- lttng - LTTng 2 tracer control command-line tool SYNOPSIS -------- [verse] *lttng* [option:--group='GROUP'] [option:--mi='TYPE'] [option:--no-sessiond | option:--sessiond-path='PATH'] [option:--quiet | option:-v | option:-vv | option:-vvv] 'COMMAND' ['COMMAND OPTIONS'] DESCRIPTION ----------- The http://lttng.org/[_Linux Trace Toolkit: next generation_] is an open source software package used for correlated tracing of the Linux kernel, user applications, and user libraries. LTTng consists of Linux kernel modules (for Linux kernel tracing) and dynamically loaded libraries (for user application and library tracing). An LTTng _session daemon_, linklttng:lttng-sessiond(8), receives commands from the command-line interface `lttng` to control the LTTng tracers. All interactions with the LTTng tracers happen through the `lttng` tool or through the liblttng-ctl library shipped with the LTTng-tools package. A _tracing domain_ is a tracer category. There are five available domains. For some commands, the domain needs to be specified with a command-line option. The domain options are: option:-j, option:--jul:: Apply command to the `java.util.logging` (JUL) domain. option:-k, option:--kernel:: Apply command to the Linux kernel domain. option:-l, option:--log4j:: Apply command to the Apache log4j 1.2 (Java) domain. option:-p, option:--python:: Apply command to the Python domain. option:-u, option:--userspace:: Apply command to the user space domain. The LTTng session daemon is a tracing registry which allows the user to interact with multiple tracers (kernel and user space) within the same container, a _tracing session_. Traces can be gathered from the Linux kernel and/or from instrumented applications (see linklttng:lttng-ust(3)). You can aggregate and read the events of LTTng traces using linklttng:babeltrace(1). To trace the Linux kernel, the session daemon needs to be running as `root`. LTTng uses a _tracing group_ to allow specific users to interact with the root session daemon. The default tracing group name is `tracing`. You can use the option:--group option to set the tracing group name to use. Session daemons can coexist. You can have a session daemon running as user Alice that can be used to trace her applications alongside a root session daemon or a session daemon running as user Bob. NOTE: It is highly recommended to start the session daemon at boot time for stable and long-term tracing. User applications instrumented with LTTng automatically register to the root session daemon and to user session daemons. This allows any session daemon to list the available traceable applications and event sources (see linklttng:lttng-list(1)). By default, the linklttng:lttng-create(1) command automatically spawns a user session daemon if none is currently running. The option:--no-sessiond general option can be set to avoid this. OPTIONS ------- option:-g, option:--group='GROUP':: Use 'GROUP' as Unix tracing group (default: `tracing`). option:-m, option:--mi='TYPE':: Print the command's result using the machine interface type 'TYPE' instead of a human-readable output. + Supported types: `xml`. + The machine interface (MI) mode converts the traditional pretty-printing to a machine output syntax. The MI mode provides a change-resistant way to access information generated by the `lttng` command-line program. + When using the MI mode, the data is printed to the standard output. Errors and warnings are printed on the standard error with the pretty-print default format. + If any error occurs during the execution of a command, the return value of the command will be different than 0. In this case, `lttng` does :not: guarantee the syntax and data validity of the generated MI output. + For the `xml` MI type, an XML schema definition (XSD) file used for validation is available: see the `src/common/mi_lttng.xsd` file in the LTTng-tools source tree. option:-n, option:--no-sessiond:: Do not automatically spawn a session daemon. option:-q, option:--quiet:: Suppress all messages, including warnings and errors. option:--sessiond-path='PATH':: Set the session daemon binary's absolute path to 'PATH'. option:-v, option:--verbose:: Increase verbosity. + Three levels of verbosity are available, which are triggered by appending additional `v` letters to the option (that is, `-vv` and `-vvv`). Program information ~~~~~~~~~~~~~~~~~~~ option:-h, option:--help:: Show help. option:--list-commands:: List available commands. option:--list-options:: List available general options. option:-V, option:--version:: Show version. COMMANDS -------- The following commands also have their own option:--help option. Tracing sessions ~~~~~~~~~~~~~~~~ linklttng:lttng-create(1):: Create a tracing session. linklttng:lttng-destroy(1):: Tear down tracing sessions. linklttng:lttng-save(1):: Save tracing session configurations. linklttng:lttng-set-session(1):: Set current tracing session. linklttng:lttng-load(1):: Load tracing session configurations. Channels ~~~~~~~~ linklttng:lttng-enable-channel(1):: Create or enable tracing channels. linklttng:lttng-disable-channel(1):: Disable tracing channels. linklttng:lttng-add-context(1):: Add context fields to a channel. Event rules ~~~~~~~~~~~ linklttng:lttng-enable-event(1):: Create or enable event rules. linklttng:lttng-disable-event(1):: Disable event rules. Status ~~~~~~ linklttng:lttng-list(1):: List tracing sessions, domains, channels, and events. linklttng:lttng-status(1):: Get the status of the current tracing session. Control ~~~~~~~ linklttng:lttng-snapshot(1):: Snapshot buffers of current tracing session. linklttng:lttng-start(1):: Start tracing. linklttng:lttng-stop(1):: Stop tracing. Resource tracking ~~~~~~~~~~~~~~~~~ linklttng:lttng-track(1):: Track specific system resources. linklttng:lttng-untrack(1):: Untrack specific system resources. Miscellaneous ~~~~~~~~~~~~~ linklttng:lttng-calibrate(1):: Quantify LTTng overhead. linklttng:lttng-help(1):: Display help information about a command. linklttng:lttng-version(1):: Show version information. linklttng:lttng-view(1):: Start trace viewer. include::common-cmd-footer.txt[] SEE ALSO -------- linklttng:lttng-sessiond(8), linklttng:lttng-relayd(8), linklttng:lttng-crash(1), linklttng:lttng-ust(3), linklttng:babeltrace(1)