This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                  IF_NAMEINDEX(3POSIX)

       The  if_nameindex()  function  shall  return  an  array  of  if_nameindex  structures,  one structure per
       interface. The end of the array is indicated by a structure with an if_index field of zero and an if_name
       field of NULL.

       Applications should call if_freenameindex() to release the memory that may be  dynamically  allocated  by
       this function, after they have finished using it.

       The if_nameindex() function may fail if:

       ENOBUFS
              Insufficient resources are available to complete the function.

       Thefollowingsectionsareinformative.

       None.

       None.

       if_nameindex — return all network interface names and indexes

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       An array of structures identifying local interfaces. A null pointer is returned upon an error, with errno
       set to indicate the error.

getsockopt(), if_freenameindex(), if_indextoname(), if_nametoindex(), setsockopt()

       The Base Definitions volume of POSIX.1‐2017, <net_if.h>

       #include <net/if.h>

       struct if_nameindex *if_nameindex(void);