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.\"     @(#)hosts.5	8.2 (Berkeley) 12/11/93
.\"
.Dd September 15, 2022
.Dt HOSTS 5
.Os
.Sh NAME
.Nm hosts
.Nd host name data base
.Sh DESCRIPTION
The
.Nm
file contains information regarding
the known hosts on the network.
It can be used in conjunction with DNS, and the NIS
maps `hosts.byaddr' and `hosts.byname', as controlled by
.Xr nsswitch.conf 5 .
For each host a single line should be present
with the following information:
.Bd -unfilled -offset indent
Internet address
official host name
aliases
.Ed
.Pp
Items are separated by any number of blanks and/or
tab characters.
A ``#'' indicates the beginning of
a comment; characters up to the end of the line are
not interpreted by routines which search the file.
.Pp
This file provides a backup used when the name server
is not running.
For the name server, it is suggested that only a few addresses
be included in this file.
These include addresses for the local interfaces that
.Xr ifconfig 8
needs at boot time and a few machines on the local network.
.Pp
Network addresses are specified in either the conventional
``.'' (dot) notation for IPv4 or colon hexadecimal notation for IPv6,
as understood by the
.Xr inet_pton 3
routine
from the Internet address manipulation library,
.Xr inet 3 .
Host names may contain any printable
character other than a field delimiter, newline,
or comment character.
.Sh FILES
.Bl -tag -width /etc/hosts -compact
.It Pa /etc/hosts
The
.Nm
file resides in
.Pa /etc .
.El
.Sh SEE ALSO
.Xr gethostbyname 3 ,
.Xr inet 3 ,
.Xr nsswitch.conf 5 ,
.Xr ifconfig 8
.Sh HISTORY
The
.Nm
file format appeared in
.Bx 4.1c .