systemd-machine-id-commit.service

Index · Directives systemd 234

## Name

systemd-machine-id-commit.service — Commit a transient machine ID to disk

## Synopsis

`systemd-machine-id-commit.service`

## Description

`systemd-machine-id-commit.service` is an early boot service responsible for committing transient `/etc/machine-id` files to a writable disk file system. See machine-id(5) for more information about machine IDs.

This service is started after `local-fs.target` in case `/etc/machine-id` is a mount point of its own (usually from a memory file system such as "`tmpfs`") and /etc is writable. The service will invoke systemd-machine-id-setup --commit, which writes the current transient machine ID to disk and unmount the `/etc/machine-id` file in a race-free manner to ensure that file is always valid and accessible for other processes. See systemd-machine-id-setup(1) for details.

The main use case of this service are systems where `/etc/machine-id` is read-only and initially not initialized. In this case, the system manager will generate a transient machine ID file on a memory file system, and mount it over `/etc/machine-id`, during the early boot phase. This service is then invoked in a later boot phase, as soon as `/etc` has been remounted writable and the ID may thus be committed to disk to make it permanent.

## See Also

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