What is Machine ID?

来源于：

https://access.redhat.com/solutions/1551183

环境

• Red Hat Enterprise Linux 7

问题

• What is Machine ID?

Raw

# hostnamectl
Machine ID: f50935fd04114b6ba00d0820cddae7f1

决议

• The /etc/machine-id file contains the unique machine ID of the local system that is set during installation. The machine ID is a single newline-terminated, hexadecimal, 32-character, lowercase machine ID string. When decoded from hexadecimal, this corresponds with a 16-byte/128-bit string.

• The machine ID is usually generated from a random source during system installation and stays constant for all subsequent boots. Optionally, for stateless systems, it is generated during runtime at boot if it is found to be empty.

• The machine ID does not change based on user configuration or when hardware is replaced. This machine ID adheres to the same format and logic as the D-Bus machine ID.

• Programs may use this ID to identify the host with a globally unique ID in the network, which does not change even if the local network configuration changes. Due to this and its greater length, it is a more useful replacement for the gethostid(3) call that POSIX specifies.

• The systemd-machine-id-setup(1) tool may be used by installer tools to initialize the machine ID at install time. Use systemd-firstboot(1) to initialize it on mounted (but not booted) system images.

• For more details,

Raw

 # man 5 machine-id