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.TH IF_INDEXTONAME "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH PROLOG
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.

.SH NAME
if_indextoname
\(em map a network interface index to its corresponding name
.SH SYNOPSIS
.LP
.nf
#include <net/if.h>
.P
char *if_indextoname(unsigned \fIifindex\fP, char *\fIifname\fP);
.fi
.SH DESCRIPTION
The
\fIif_indextoname\fR()
function shall map an interface index to its corresponding name.
.P
When this function is called,
.IR 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
.IR ifindex .
.SH "RETURN VALUE"
If
.IR ifindex
is an interface index, then the function shall return the value supplied in
.IR ifname ,
which points to a buffer now containing the interface name. Otherwise,
the function shall return a null pointer and set
.IR errno
to indicate the error.
.SH ERRORS
The
\fIif_indextoname\fR()
function shall fail if:
.TP
.BR ENXIO
The interface does not exist.
.LP
.IR "The following sections are informative."
.SH "EXAMPLES"
None.
.SH "APPLICATION USAGE"
None.
.SH "RATIONALE"
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIgetsockopt\fR\^(\|)",
.IR "\fIif_freenameindex\fR\^(\|)",
.IR "\fIif_nameindex\fR\^(\|)",
.IR "\fIif_nametoindex\fR\^(\|)",
.IR "\fIsetsockopt\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2008,
.IR "\fB<net_if.h>\fP"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .