Manual Pages  — HOSTS

The hosts 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 nsswitch.conf(5). For each host a single line should be present with the following information:

Internet address
official host name
aliases

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.

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 ifconfig(8) needs at boot time and a few machines on the local network.

Network addresses are specified in either the conventional ``.'' (dot) notation for IPv4 or colon hexadecimal notation for IPv6, as understood by the inet_pton(3) routine from the Internet address manipulation library, inet(3). Host names may contain any printable character other than a field delimiter, newline, or comment character.

gethostbyname(3), inet(3), nsswitch.conf(5), ifconfig(8)