--- name: "lttng-view" section: "1" platform: "linux" package: "lttng-tools" version: "2.13.15-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/lttng-view" --- # lttng-view(1) Launch an LTTng trace reader ## NAME lttng-view - 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**=*SESSION* option 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** option 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)](/babeltrace2/1.md) or, if it’s not available, [**babeltrace**(1)](/babeltrace/1.md). Override which trace reader to launch with the **--viewer** option. See the “EXAMPLES” section below for usage examples. ## OPTIONS See [**lttng**(1)](/lttng/1.md) 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)](/babeltrace2/1.md) if it’s available. Otherwise, it tries to use [**babeltrace**(1)](/babeltrace/1.md). ### 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 **$HOME**. Useful when the Unix user running the commands has a non-writable home directory. **LTTNG\_MAN\_BIN\_PATH** Absolute path to the manual pager to use to read the LTTng command-line help (with [**lttng-help**(1)](/lttng-help/1.md) or with the **--help** option) instead of **/usr/bin/man**. **LTTNG\_SESSION\_CONFIG\_XSD\_PATH** Path to the directory containing the **session.xsd** recording session configuration XML schema. **LTTNG\_SESSIOND\_PATH** Absolute path to the LTTng session daemon binary (see [**lttng-sessiond**(8)](/lttng-sessiond/8.md)) to spawn from the [**lttng-create**(1)](/lttng-create/1.md) command. The **--sessiond-path** general option overrides this environment variable. ## FILES **$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/1.md). [**lttng-create**(1)](/lttng-create/1.md) and [**lttng-set-session**(1)](/lttng-set-session/1.md) set the current recording session. **$LTTNG\_HOME/lttng-traces** Default output directory of LTTng traces in local and snapshot modes. Override this path with the **--output** option of the [**lttng-create**(1)](/lttng-create/1.md) command. **$LTTNG\_HOME/.lttng** Unix user’s LTTng runtime and configuration directory. **$LTTNG\_HOME/.lttng/sessions** Default directory containing the Unix user’s saved recording session configurations (see [**lttng-save**(1)](/lttng-save/1.md) and [**lttng-load**(1)](/lttng-load/1.md)). **/etc/lttng/sessions** Directory containing the system-wide saved recording session configurations (see [**lttng-save**(1)](/lttng-save/1.md) and [**lttng-load**(1)](/lttng-load/1.md)). **Note**\ **$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.** See the **--viewer** option. ``` $ lttng view --viewer='/usr/bin/my-reader -zK --details=3' \ my-session ``` ## RESOURCES • LTTng project website \ • LTTng documentation \ • LTTng bug tracker \ • Git repositories \ • GitHub organization \ • Continuous integration \ • Mailing list \ for support and development: **lttng-dev@lists.lttng.org** • IRC channel \: **#lttng** on **irc.oftc.net** ## COPYRIGHT This program is part of the LTTng-tools project. LTTng-tools is distributed under the GNU General Public License version 2 \. See the **LICENSE** \ file for details. ## THANKS Special thanks to Michel Dagenais and the DORSAL laboratory \ 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 [**babeltrace2**(1)](/babeltrace2/1.md), [**lttng**(1)](/lttng/1.md)