LTTNG-SET-SESSION(1)

📦
version 2.15.1 · 12 versions
, in ubuntu stonking

💖 LTTNG-SET-SESSION 💖

okay bestie, sit down, hydrate, because today we're talking about lttng-set-session — the lil glow-up command from the LTTng Manual, section 1. It's short, it's sweet, it's giving "tiny command, big main character energy." 🎀

✨ NAME ✨

lttng-set-session — Set the current LTTng recording session

🌸 SYNOPSIS 🌸

lttng [GENERAL OPTIONS] set-session SESSION

🦋 DESCRIPTION 🦋

So here's the vibe: the lttng set-session command sets the current recording session of your Unix user to the recording session named SESSION. That's it. That's the whole job. She's focused, she's efficient, she ate. 💅

Wanna actually understand what a "current recording session" even is? Go read lttng-concepts(7) — it's the lore drop you need, fr fr.

The way this works under the hood: the set-session command effectively updates the $LTTNG_HOME/.lttngrc file. So yeah, it's literally just writing your fave session's name down so future-you remembers who you were. It's giving "pinned post." 📌

And if you ever need to see who's even available to pick from — list the recording sessions of your Unix user, or of all users if your Unix user is root, within the connected session daemon with the lttng-list(1) command. Choose your fighter wisely, bestie. 👑

✨ OPTIONS ✨

Peep lttng(1) for the GENERAL OPTIONS — those are the shared ones, not this command's personal stash.

💜 Program information 💜

  • -h, --help — Show help. Bestie. Help. This option attempts to launch /usr/bin/man to view this manual page. You can override the manual pager path with the LTTNG_MAN_BIN_PATH environment variable, if /usr/bin/man isn't your type.
  • --list-options — List available command options and quit. No notes, just receipts. 🧾

🌈 EXIT STATUS 🌈

  • 0 — Success 🎉 (she did it, she slayed)
  • 1 — Command error 😭
  • 2 — Undefined command 💀
  • 3 — Fatal error 🚨
  • 4 — Command warning (something went wrong during the command) 🙈

🍓 ENVIRONMENT 🍓

These are the env vars that change the whole mood. Read them, know them, iykyk.

  • LTTNG_ABORT_ON_ERROR — Set to 1 to abort the process after the first error is encountered. No second chances, periodt.
  • 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. We love a flexible queen. 🫶
  • 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 mode is cute but she's missing the new stuff. 🕰️
  • 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. Bold of you to reject the emoji lifestyle but okay, respect. ✋
  • 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. (Yes, the option wins. She's the main character here.)
  • 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. Rainbow mode forever. 🌈
    • never — Never emit SGR codes. Monochrome minimalism.
  • 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. (Yes, this is literally where this whole command does its thing. That's the ✨ impact ✨.)
  • $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.

💫 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. Not all heroes wear capes, some just file the weirdest bugs imaginable and honestly? iconic. 🙌

🔥 SEE ALSO 🔥

lttng(1), lttng-create(1), lttng-concepts(7)

and that's the whole page bestie!! 💖 this was LTTng 2.15.1, dated 14 June 2021, manual page LTTNG-SET-SESSION(1) — go set your session, you absolute legend. mwah. 💅✨

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