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+.\" Copyright (c) 1987, 1990, 1993
+.\" The Regents of the University of California. All rights reserved.
+.\"
+.\" SPDX-License-Identifier: BSD-4-Clause-UC
+.\"
+.\" @(#)hostname.7 8.2 (Berkeley) 12/30/93
+.\" $FreeBSD: src/share/man/man7/hostname.7,v 1.7 2004/07/03 18:29:23 ru Exp $
+.\"
+.\" 2008-06-11, mtk, Taken from FreeBSD 6.2 and modified for Linux.
+.\"
+.TH hostname 7 2022-10-30 "Linux man-pages 6.05.01"
+.SH NAME
+hostname \- hostname resolution description
+.SH DESCRIPTION
+Hostnames are domains, where a domain is a hierarchical, dot-separated
+list of subdomains; for example, the machine "monet", in the "example"
+subdomain of the "com" domain would be represented as "monet.example.com".
+.PP
+Each element of the hostname must be from 1 to 63 characters long and the
+entire hostname, including the dots, can be at most 253 characters long.
+Valid characters for hostnames are
+.BR ASCII (7)
+letters from
+.I a
+to
+.IR z ,
+the digits from
+.I 0
+to
+.IR 9 ,
+and the hyphen (\-).
+A hostname may not start with a hyphen.
+.PP
+Hostnames are often used with network client and server programs,
+which must generally translate the name to an address for use.
+(This task is generally performed by either
+.BR getaddrinfo (3)
+or the obsolete
+.BR gethostbyname (3).)
+.PP
+Hostnames are resolved by the NSS framework in glibc according
+to the
+.B hosts
+configuration in
+.BR nsswitch.conf .
+The DNS-based name resolver
+(in the
+.B dns
+NSS service module) resolves them in the following fashion.
+.PP
+If the name consists of a single component, that is, contains no dot,
+and if the environment variable
+.B HOSTALIASES
+is set to the name of a file,
+that file is searched for any string matching the input hostname.
+The file should consist of lines made up of two white-space separated strings,
+the first of which is the hostname alias,
+and the second of which is the complete hostname
+to be substituted for that alias.
+If a case-insensitive match is found between the hostname to be resolved
+and the first field of a line in the file, the substituted name is looked
+up with no further processing.
+.PP
+If the input name ends with a trailing dot,
+the trailing dot is removed,
+and the remaining name is looked up with no further processing.
+.PP
+If the input name does not end with a trailing dot, it is looked up
+by searching through a list of domains until a match is found.
+The default search list includes first the local domain,
+then its parent domains with at least 2 name components (longest first).
+For example,
+in the domain cs.example.com, the name lithium.cchem will be checked first
+as lithium.cchem.cs.example and then as lithium.cchem.example.com.
+lithium.cchem.com will not be tried, as there is only one component
+remaining from the local domain.
+The search path can be changed from the default
+by a system-wide configuration file (see
+.BR resolver (5)).
+.SH SEE ALSO
+.BR getaddrinfo (3),
+.BR gethostbyname (3),
+.BR nsswitch.conf (5),
+.BR resolver (5),
+.BR mailaddr (7),
+.BR named (8)
+.PP
+.UR http://www.ietf.org\:/rfc\:/rfc1123.txt
+IETF RFC\ 1123
+.UE
+.PP
+.UR http://www.ietf.org\:/rfc\:/rfc1178.txt
+IETF RFC\ 1178
+.UE
+.\" .SH HISTORY
+.\" Hostname appeared in
+.\" 4.2BSD.