systemd-machine-id-commit.service

systemd
Developer Didier Roche didrocks@ubuntu.com
systemd-machine-id-commit.service 8
systemd-machine-id-commit.service Commit transient machine-id to disk

`systemd-machine-id-commit.service`

`/usr/lib/systemd/systemd-machine-id-commit`

## Description

`systemd-machine-id-commit.service` is a service responsible for committing any transient `/etc/machine-id` file to a writable file system. See machine-id 5 for more information about this file.

This service is started shortly after `local-fs.target` if `/etc/machine-id` is an independent mount point (probably a tmpfs one) and /etc is writable. `systemd-machine-id-commit` will then write current machine ID to disk and unmount the transient `/etc/machine-id` file in a race-free manner to ensure that file is always valid for other processes.

Note that the traditional way to initialize the machine ID in `/etc/machine-id` is to use `systemd-machine-id-setup` by system installer tools. You can also use systemd-firstboot 1 to initialize the machine ID on mounted (but not booted) system images. The main use case for that service is `/etc/machine-id` being an empty file at boot and initrd chaining to systemd giving it a read only file system that will be turned read-write later during the boot process.

There is no consequence if that service fails other than a newer machine-id will be generated during next system boot.

## See Also

systemd 1, systemd-machine-id-commit 1, systemd-machine-id-setup 1, machine-id 5, systemd-firstboot 1