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machine-instance

machine-instance Function

Syntax:

machine-instance ⟨no arguments⟩ → description

Arguments and Values:

description—a string or nil.

Description:

Returns a string that identifies the particular instance of the computer hardware on which Common Lisp is running, or nil if no such string can be computed.

Examples:

(machine-instance) 
→ "ACME.COM" 
<i><sup>or</sup>→</i> "S/N 123231" 
<i><sup>or</sup>→</i> "18.26.0.179" 
<i><sup>or</sup>→</i> "AA-00-04-00-A7-A4"

Affected By:

The machine instance, and the implementation.

See Also:

machine-type, machine-version

Expanded Reference: machine-instance​

Basic Usage​

machine-instance returns a string that identifies the particular machine (host) on which the Lisp implementation is running. The exact content is implementation-dependent.

(or (stringp (machine-instance)) (null (machine-instance)))
;; => T

Typical Return Values​

Different implementations may return hostnames, fully qualified domain names, or other identifiers. The function may also return NIL if no meaningful value can be determined.

;; On SBCL running on a Linux host, returns the hostname string
;; On some implementations where host info is unavailable, returns NIL
(stringp (machine-instance))
;; => impl-dependent

Using in Diagnostic Output​

machine-instance is commonly used alongside other environment-querying functions to produce diagnostic or logging information.

(stringp (format nil "Running on ~A (~A ~A)"
                 (or (machine-instance) "unknown host")
                 (or (machine-type) "unknown type")
                 (or (machine-version) "unknown version")))
;; => T

Important Notes​

The return value is a string or NIL. The format and content are entirely implementation-dependent -- there is no portable way to rely on the structure of the returned string.