id returns a stable machine identifier.

Supports:

• AIX (via the machine component of uname syscall)
• BSD (via sysctl hw.uuid, sysctl kern.hostuuid, /etc/hostid, hostid, or kenv -q smbios.system.uuid)
• Darwin (via gethostuuid)
• Linux (via /var/lib/dbus/machine-id, /etc/machine-id or /sys/class/dmi/id/product_uuid)
• Windows (via registry SOFTWARE\Microsoft\Cryptography\MachineGuid)
• z/OS