Ubuntu Manpage: systemd-machine-id-setup - Initialize the machine ID in /etc/machine-id

Provided by: systemd_256.5-2ubuntu3.1_amd64

NAME

       systemd-machine-id-setup - Initialize the machine ID in /etc/machine-id

SYNOPSIS

       systemd-machine-id-setup

DESCRIPTION

systemd-machine-id-setup may be used by system installer tools to initialize the machine
ID stored in /etc/machine-id at install time, with a provisioned or randomly generated ID.
See machine-id(5) for more information about this file.

If the tool is invoked without the --commit switch, /etc/machine-id is initialized with a
valid, new machine ID if it is missing or empty. The new machine ID will be acquired in
the following fashion:

1. If a valid machine ID is stored in /run/machine-id, the machine ID is copied and used
to initialize the machine ID in /etc/machine-id. This step is skipped if --root= is
specified or running in a chroot environment.

2. If a valid D-Bus machine ID is already configured for the system, the D-Bus machine ID
is copied and used to initialize the machine ID in /etc/machine-id.

3. If a valid machine ID is provided through system.machine_id credential, the machine ID
is copied and used to initialize the machine ID in /etc/machine-id. This step is
skipped if --root= is specified or running in a chroot environment.

4. If run inside a KVM virtual machine and a UUID is configured (via the -uuid option),
this UUID is used to initialize the machine ID. The caller must ensure that the UUID
passed is sufficiently unique and is different for every booted instance of the VM.
This step is skipped if --root= is specified or running in a chroot environment.

5. Similarly, if run inside a Linux container environment and a UUID is configured for
the container, this is used to initialize the machine ID. For details, see the
documentation of the Container Interface[1]. This step is skipped if --root= is
specified or running in a chroot environment.

6. Otherwise, a new ID is randomly generated.

The --commit switch may be used to commit a transient machined ID to disk, making it
persistent. For details, see below.

Use systemd-firstboot(1) to initialize the machine ID on mounted (but not booted) system
images.

OPTIONS

The following options are understood:

--root=path
Takes a directory path as argument. All paths operated on will be prefixed with the
given alternate root path, 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. This is similar to --root=
as described above, but operates on 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
is enforced when operating on the disk image specified via --image=, see above. If not
specified 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 may be used to 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. This may happen because /etc/ is 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. The command will write the current transient
machine ID to disk and unmount the /etc/machine-id mount point in a race-free manner
to ensure 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 generated or committed after the operation is complete.

Added in version 231.

-h, --help
Print a short help text and exit.

--version
Print a short version string and exit.

EXIT STATUS

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

NOTES