LTTNG-VIEW(1)

📦
version 2.15.1 · 12 versions
, in ubuntu stonking

💖 NAME 💖

lttng-view — bestie, this launches an LTTng trace reader. That's it. That's the whole job. 👑

✨ SYNOPSIS ✨

lttng [GENERAL OPTIONS] view [--viewer=READER]
      [SESSION | --trace-path=DIR]

🌸 DESCRIPTION

Okay so the lttng view command literally just launches an external trace reader to read the current traces of… well, depends on what you hand it, bestie:

  • With the SESSION argument — it reads the recording session named SESSION. 🎀
  • With the --trace-path=DIR option — it reads the local file system directory DIR. 💅
  • Otherwise — it reads the current recording session (peep concepts(1) if you wanna learn more about the current recording session, iykyk).

Now the big vibe check: with the SESSION argument, or without the --trace-path option, the mode of the selected recording session may NOT be network streaming or live. Not negotiable. Periodt.

By default, the view command attempts to launch babeltrace2(1) or, if it's not available, babeltrace(1). You can override which trace reader to launch with the --viewer option. 🦋

See the “EXAMPLES” section below for usage examples — they're cute, go look.

🎀 OPTIONS 🎀

See lttng(1) 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. Just swapping out the ending, slay.
  • -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) if it's available. Otherwise, it tries to use babeltrace(1). So it's giving backup plan energy, honestly.

🌈 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. Iconic. Short. Effective. ✨

🦋 EXIT STATUS 🦋

  • 0 — Success 🎉 (the good ending)
  • 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. One strike and we're out, no cap.
  • 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. (Been there. Rough.)
  • 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. So, like, retro vibes but you're missing stuff, ngl.
  • 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. 👑 One of them wins, and it's not the env var.
  • 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. So it remembers, bestie. 🧠✨
  • $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)).
  • /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. 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

Look at that custom reader eating, honestly. 🔥

🌟 RESOURCES 🌟

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. (Unusual test cases are the real MVPs, fr fr.)

🦋 SEE ALSO 🦋

babeltrace2(1), lttng(1)

Okay bestie that's the whole page, go read some traces 💅✨ — this was from the LTTng Manual, version LTTng 2.15.1, dated 22 April 2026. Love u, bye! 🎀💜

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