systemd systemd-machine-tag@.service 8 systemd-machine-tag@.service Add a machine tag to the host systemd-machine-tag@.service systemd-machine-tag@TAG.service is a service template that adds the machine tag TAG (taken from the instance name) to the host's list of machine tags. Whenever an instance of this template is pulled in, the corresponding tag is added; the operation is idempotent, so pulling it in repeatedly has no further effect. The primary use of this template is automatic, hardware-driven tagging: the SYSTEMD_MACHINE_TAG udev property, when set on a device, causes the matching instance of this template to be pulled in (via SYSTEMD_WANTS=), so that plugging in or detecting a specific device automatically tags the host. See systemd.device5 for details on the SYSTEMD_WANTS= mechanism. Machine tags may be inspected and edited with the tags verb of hostnamectl1, and are stored in the TAGS= field of machine-info5. Each tag must be 1…255 characters long and consist only of ASCII alphanumeric characters, - and .. systemd1 hostnamectl1 systemd-hostnamed.service8 machine-info5 udev7