SYSTEMD-....SERVICE(8)

💖 SYSTEMD-....SERVICE(8) 💖

okay bestie, this one lives in the systemd-machine-id-commit.service section of the systemd manual — yes the title is literally SYSTEMD-....SERVICE(8) with the dots, that's not a typo, that's just how they do it ✨

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🎀 NAME 🎀

systemd-machine-id-commit.service — the lil service whose whole job is committing a transient machine ID to disk 🫶

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🌸 SYNOPSIS 🌸

systemd-machine-id-commit.service

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✨ DESCRIPTION ✨

so systemd-machine-id-commit.service is an early boot service, and its entire main character moment is committing transient /etc/machine-id files to a writable disk file system. if you wanna know what a machine ID even is, go read machine-id(5), it's giving lore 💅

this service gets started after local-fs.target — but only in case /etc/machine-id is a mount point of its own (usually from a memory file system like "tmpfs") and /etc is writable. when it runs, it invokes systemd-machine-id-setup --commit, which writes the current transient machine ID to disk and unmounts the /etc/machine-id file in a race-free manner so that the file is always valid and accessible for other processes. no cap, that's the whole point. see systemd-machine-id-setup(1) for the deets 🌈

the main use case, like the iconic scenario, is systems where /etc/machine-id is read-only and initially not initialized. in that case, the system manager generates a transient machine ID file on a memory file system, and mounts it over /etc/machine-id, during the early boot phase. then this service gets invoked in a later boot phase, as soon as /etc/ has been remounted writable — and that's when the ID may be committed to disk to make it permanent. ate. no crumbs. periodt 👑

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🦋 SEE ALSO 🦋

• systemd(1)
• systemd-machine-id-setup(1)
• machine-id(5)
• systemd-firstboot(1)

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fr fr that's the whole page. no hidden flags, no secret options, just a tiny little boot service doing its one job flawlessly 🍓

okay bye ily, this was systemd version 262.1 — mwah 💖 🧚‍♀️ ⭐