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| .TH IF_NAMETOINDEX 3 2017-09-15 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| if_nametoindex, if_indextoname \- mappings between network interface |
| names and indexes |
| .SH SYNOPSIS |
| .nf |
| .B #include <net/if.h> |
| .PP |
| .BI "unsigned int if_nametoindex(const char *" "ifname" ); |
| .PP |
| .BI "char *if_indextoname(unsigned int ifindex, char *" ifname ); |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR if_nametoindex () |
| function returns the index of the network interface |
| corresponding to the name |
| .IR ifname . |
| .PP |
| The |
| .BR if_indextoname () |
| function returns the name of the network interface |
| corresponding to the interface index |
| .IR ifindex . |
| The name is placed in the buffer pointed to by |
| .IR ifname . |
| The buffer must allow for the storage of at least |
| .B IF_NAMESIZE |
| bytes. |
| .SH RETURN VALUE |
| On success, |
| .BR if_nametoindex () |
| returns the index number of the network interface; |
| on error, 0 is returned and |
| .I errno |
| is set appropriately. |
| .PP |
| On success, |
| .BR if_indextoname () |
| returns |
| .IR ifname ; |
| on error, NULL is returned and |
| .I errno |
| is set appropriately. |
| .SH ERRORS |
| .BR if_nametoindex () |
| may fail and set |
| .I errno |
| if: |
| .TP |
| .B ENODEV |
| No interface found with given name. |
| .PP |
| .BR if_indextoname () |
| may fail and set |
| .I errno |
| if: |
| .TP |
| .B ENXIO |
| No interface found for the index. |
| .PP |
| .BR if_nametoindex () |
| and |
| .BR if_indextoname () |
| may also fail for any of the errors specified for |
| .BR socket (2) |
| or |
| .BR ioctl (2). |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lbw34 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR if_nametoindex (), |
| .BR if_indextoname () |
| T} Thread safety MT-Safe |
| .TE |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, RFC\ 3493. |
| .PP |
| This function first appeared in BSDi. |
| .SH SEE ALSO |
| .BR getifaddrs (3), |
| .BR if_nameindex (3), |
| .BR ifconfig (8) |