systemd systemd-id128 1 systemd-id128 Generate and print sd-128 identifiers systemd-id128 OPTIONS new systemd-id128 OPTIONS machine-id systemd-id128 OPTIONS boot-id systemd-id128 OPTIONS invocation-id systemd-id128 OPTIONS var-partition-uuid systemd-id128 OPTIONS show NAME|UUID id128 may be used to conveniently print sd-id1283 UUIDs. What identifier is printed depends on the specific verb. With new, a new random identifier will be generated. With machine-id, the identifier of the current machine will be printed. See machine-id5. With boot-id, the identifier of the current boot will be printed. With invocation-id, the identifier of the current service invocation will be printed. This is available in systemd services. See systemd.exec5. With show, well-known IDs are printed (for now, only GPT partition type UUIDs), along with brief identifier strings. When no arguments are specified, all known IDs are shown. When arguments are specified, they may be the identifiers or ID values of one or more known IDs, which are then printed with their name, or arbitrary IDs, which are then printed with a placeholder name. Combine with --uuid to list the IDs in UUID style, i.e. the way GPT partition type UUIDs are usually shown. machine-id, boot-id, and show may be combined with the --app-specific=app-id switch to generate application-specific IDs. See sd_id128_get_machine3 for the discussion when this is useful. Support for show --app-specific= was added in version 255. var-partition-uuid prints a UUID which, following the Discoverable Partitions Specification, should be used as the GPT partition UUID for /var/, being derived from the GPT partition type, keyed by the local /etc/machine-id. Added in version 257. The following options are understood: -p --pretty Generate output as programming language snippets. -P --value Only print the value. May be combined with -u/--uuid. -a app-id --app-specific=app-id With this option, identifiers will be printed that are the result of hashing the application identifier app-id and another ID. The app-id argument must be a valid sd-id128 string identifying the application. When used with machine-id, the other ID will be the machine ID as described in machine-id5, when used with boot-id, the other ID will be the boot ID, and when used with show, the other ID or IDs should be specified via the positional arguments. -u --uuid Generate output as a UUID formatted in the "canonical representation", with five groups of digits separated by hyphens. See the Wikipedia entry for Universally Unique Identifiers for more discussion. On success 0 is returned, and a non-zero failure code otherwise. $ systemd-id128 show --value user-home 773f91ef66d449b5bd83d683bf40ad16 $ systemd-id128 show --value --uuid user-home 773f91ef-66d4-49b5-bd83-d683bf40ad16 $ systemd-id128 show 773f91ef-66d4-49b5-bd83-d683bf40ad16 NAME ID user-home 773f91ef66d449b5bd83d683bf40ad16 $ systemd-id128 machine-id -u 3a9d668b-4db7-4939-8a4a-5e78a03bffb7 $ systemd-id128 new -u 1fb8f24b-02df-458d-9659-cc8ace68e28a $ systemd-id128 machine-id -u -a 1fb8f24b-02df-458d-9659-cc8ace68e28a 47b82cb1-5339-43da-b2a6-1c350aef1bd1 $ systemd-id128 -Pu show 3a9d668b-4db7-4939-8a4a-5e78a03bffb7 \ -a 1fb8f24b-02df-458d-9659-cc8ace68e28a 47b82cb1-5339-43da-b2a6-1c350aef1bd1 On a given machine with the ID 3a9d668b-4db7-4939-8a4a-5e78a03bffb7, for the application 1fb8f24b-02df-458d-9659-cc8ace68e28a, we generate an application-specific machine ID (47b82cb1-5339-43da-b2a6-1c350aef1bd1). If we want to later recreate the same calculation on a different machine, we need to specify both IDs explicitly as parameters to show. systemd1 sd-id1283 sd_id128_get_machine3