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_INDEXTONAME(3POSIX)

       The if_indextoname() function shall map an interface index to its corresponding name.

       When  this  function  is  called,  ifname  shall  point  to a buffer of at least {IF_NAMESIZE} bytes. The
       function shall place in this buffer the name of the interface with index ifindex.

       The if_indextoname() function shall fail if:

       ENXIO  The interface does not exist.

       Thefollowingsectionsareinformative.

       None.

       None.

       if_indextoname — map a network interface index to its corresponding name

       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.

       If ifindex is an interface index, then the function shall return the  value  supplied  in  ifname,  which
       points to a buffer now containing the interface name. Otherwise, the function shall return a null pointer
       and set errno to indicate the error.

getsockopt(), if_freenameindex(), if_nameindex(), if_nametoindex(), setsockopt()

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

       #include <net/if.h>

       char *if_indextoname(unsigned ifindex, char *ifname);