SYSTEMD-MACHINE-ID-SETUP(1)

💖 SYSTEMD-MACHINE-ID-SETUP(1) 💖

okay bestie, this is systemd-machine-id-setup from the systemd manual — the lil glow-up artist that gives your machine its one true ID ✨

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🌸 NAME 🌸

systemd-machine-id-setup — initialize the machine ID in /etc/machine-id

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🎀 SYNOPSIS 🎀

systemd-machine-id-setup

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✨ DESCRIPTION ✨

so like, systemd-machine-id-setup is the tool your system installer besties call to set up the machine ID living in /etc/machine-id at install time — either with a provisioned ID or a freshly randomized one 🎲. wanna know more about that file? go read machine-id(5), it spills all the tea 💅.

If you run the tool without the --commit switch, /etc/machine-id gets initialized with a valid, brand-new machine ID if it's missing or empty. and how does it pick that new ID? glad you asked, here's the whole lineup:

1. If there's a valid machine ID chillin' in /run/machine-id, it gets copied over and used to initialize the machine ID in /etc/machine-id. ⚠️ this step is skipped if --root= is specified, or if you're running in a chroot environment.
2. If a valid D-Bus machine ID is already configured for the system, that D-Bus machine ID gets copied and used to initialize the machine ID in /etc/machine-id.
3. If a valid machine ID is provided through the system.machine_id credential, that machine ID gets copied and used to initialize the machine ID in /etc/machine-id. ⚠️ skipped if --root= is specified or running in a chroot environment.
4. If you're running inside a KVM virtual machine and a UUID is configured (via the -uuid option), that UUID is used to initialize the machine ID. heads up tho: the caller has to make sure the UUID they pass is sufficiently unique and different for every single booted instance of the VM 👑. ⚠️ skipped if --root= is specified or running in a chroot environment.
5. Same vibe for Linux containers: if you're in a container environment and a UUID is configured for the container, that gets used to initialize the machine ID. for the deets, check the Container Interface docs (linked down in NOTES 🫶). ⚠️ skipped if --root= is specified or running in a chroot environment.
6. and if literally none of that applies? a brand-new ID gets randomly generated. iconic. 🦋

The --commit switch is the glow-up button: it commits a transient machine ID to disk and makes it persistent. more on that below 👇

also, if you're initializing the machine ID on a mounted (but not booted) system image, use systemd-firstboot(1) instead 💖

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💅 OPTIONS 💅

here's everything this baby understands:

• --root=path — takes a directory path as its argument. every path it operates on gets prefixed with that alternate root path you gave it — including the path for /etc/machine-id itself. 🏠

Added in version 212.

• --image=path — takes a path to a device node or regular file as argument. it's basically --root= but for a disk image instead of a directory tree 💾.

Added in version 249.

• --image-policy=policy — takes an image policy string as argument, as per systemd.image-policy(7). the policy gets enforced when operating on the disk image specified via --image=, see above. if you don't specify one, it defaults to the "*" policy, i.e. all recognized file systems in the image are used 🌈.
• --commit — commit a transient machine ID to disk 🫶. this command can convert a transient machine ID into a persistent one. a transient machine ID file is one that was bind mounted from a memory file system (usually "tmpfs") to /etc/machine-id during the early phase of the boot process — which can happen because /etc/ was initially read-only and was missing a valid machine ID file at that point 😭.

This command will execute no operation if /etc/machine-id is not mounted from a memory file system, or if /etc/ is read-only. otherwise, it writes the current transient machine ID to disk and unmounts the /etc/machine-id mount point in a race-free manner, so that this file is always valid and accessible for other processes 👑.

This command is primarily used by the systemd-machine-id-commit.service(8) early boot service.

Added in version 227.

• --print — print the machine ID that was generated or committed, after the operation is complete 🖨️✨.

Added in version 231.

• -h, --help — print a short help text and exit. classic.
• --version — print a short version string and exit. also classic.

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🔥 EXIT STATUS 🔥

On success, 0 is returned. otherwise you get a non-zero failure code 😭.

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🌈 SEE ALSO 🌈

systemd(1), machine-id(5), systemd-machine-id-commit.service(8), dbus-uuidgen(1), systemd-firstboot(1)

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📝 NOTES 📝

1. Container Interface https://systemd.io/CONTAINER_INTERFACE

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and that's the whole page bestie, no cap 💖 this was systemd version 262.1's SYSTEMD-MACHINE-ID-SETUP(1) — go forth and give your machine an identity, main character energy only 👑✨🎀