.\" Portions Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved. .\" $NetBSD: hosts.5,v 1.4 1994/11/30 19:31:20 jtc Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)hosts.5 8.2 (Berkeley) 12/11/93 .\" .Dd December 11, 1993 .Dt HOSTS 5 .Os BSD 4.2 .Sh NAME .Nm hosts .Nd host name data base .Sh DESCRIPTION The .Nm hosts file contains information regarding the known hosts on the network. 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 Network addresses may either be specified for IP version 4 or version 6. IP version 4 addresses are specified in the conventional dotted address notation. IP version 6 addresses are specified using the colon-separated notation described in RFC1924. .Pp Host names may contain any printable character other than a field delimiter, newline, or comment character. .Sh INTERACTION WITH DIRECTORY SERVICES Processes generally find host-related information using the routines described in .Xr gethostent 3 , .Xr getipnodebyname 3 , .Xr getaddrinfo 3 , and .Xr getnameinfo 3 . On Mac OS X, these functions interact with the .Xr DirectoryService 8 daemon, which reads the /etc/hosts file as well as searching other directory information services, most notably the Domain Name System (DNS). .Sh FILES .Bl -tag -width /etc/hosts -compact .It Pa /etc/hosts .El .Sh SEE ALSO .Xr gethostent 3 , .Xr getipnodebyname 3 , .Xr getaddrinfo 3 , .Xr getnameinfo 3 , .Xr DirectoryService 8 .Rs .%T "RFC1924: A Compact Representation of IPv6 Addresses" .Re .Sh HISTORY The .Nm file format appeared in .Bx 4.2 .