hostid

Additional Notes

hostid prints the unique numeric identifier of the current host as a 32-bit hexadecimal number. This identifier is typically set at system installation time and stored in /etc/hostid or derived from the system's network address.

The host ID is used by some software licensing systems to bind licenses to a specific machine. It can be set manually with the hostid command (as root) or by writing to /etc/hostid. The value is not the same as the machine's IP address or hostname.

Syntax

hostid [options]

Parameters

• options: Flags that change how hostid behaves.
• target: Optional file, device, interface, user, service, or command target when the command supports one.

Common Options

• --help: Display help.
• --version: Show version information.

Examples

hostid

Print the current host ID as a hexadecimal number.

Practical Notes

• The output is a single hexadecimal string, such as 002a3f44.
• The host ID can be set with hostid NEWID (requires root) or by writing a 4-byte value to /etc/hostid.
• Host IDs are used by some enterprise software (e.g., Oracle, some FlexLM applications) for license locking.
• Changing the host ID may invalidate existing software licenses.
• The host ID is usually derived from the IP address or a random value generated at installation time.