gethostid() — Get the unique identifier of the current host

Standards

Standards / Extensions	C or C++	Dependencies
XPG4.2 Single UNIX Specification, Version 3	both

X/Open:

#define _XOPEN_SOURCE_EXTENDED 1
#include <unistd.h>

long gethostid(void);

Berkeley sockets:

#define _OE_SOCKETS
#include <unistd.h>

int gethostid();

The gethostid() call gets the unique 32-bit identifier for the current host. This value is the default home Internet address.

Special behavior for C++: To use this function with C++, you must use the _XOPEN_SOURCE_EXTENDED 1 feature test macro.

If successful, gethostid() returns the 32-bit identifier of the current host, which should be unique across all hosts.

If unsuccessful, gethostid() returns -1 and stores the error value in errno. For return codes, see z/OS UNIX System Services Messages and Codes.