NAME
systemd-id128 - Generate and print sd-128 identifiers
SYNOPSIS
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...]
DESCRIPTION
id128 may be used to conveniently print sd-id128(3) 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-id(5).
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.exec(5).
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_machine(3) 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[1], 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.
OPTIONS
The following options are understood:
-p, --pretty
Added in version 240.
-P, --value
Added in version 255.
-aapp-id, --app-specific=app-id
Added in version 240.
-u, --uuid
Added in version 244.
--no-pager
--no-legend
--json=MODE
-j
-h, --help
--version
EXIT STATUS
On success 0 is returned, and a non-zero failure code otherwise.
EXAMPLES
Example 1. Show a well-known UUID
$ 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 773f91ef66d449b5bd83d683bf40ad16Example 2. Generate an application-specific UUID
$ 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 \
\n
-a 1fb8f24b-02df-458d-9659-cc8ace68e28a
47b82cb1-5339-43da-b2a6-1c350aef1bd1On 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.
SEE ALSO
systemd(1), sd-id128(3), sd_id128_get_machine(3)
NOTES
- 1.
Discoverable Partitions Specification
- 2.
Universally Unique Identifiers