2008-06-11 21:24:46 +00:00
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.\" Copyright (c) 1987, 1990, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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accept.2, bind.2, connect.2, getpeername.2, getpriority.2, getsockname.2, getsockopt.2, ioctl.2, killpg.2, listen.2, lseek.2, readlink.2, recv.2, send.2, setpgid.2, setreuid.2, shutdown.2, socket.2, socketpair.2, syscall.2, truncate.2, alloca.3, btree.3, daemon.3, dbopen.3, err.3, exec.3, fclose.3, ferror.3, fflush.3, fopen.3, fread.3, fseek.3, fts.3, hash.3, mpool.3, popen.3, queue.3, rcmd.3, recno.3, rexec.3, scanf.3, setbuf.3, stdarg.3, stdio.3, strtod.3, hostname.7, mdoc.7, mdoc.samples.7: srcfix: LICENSE: s/BSD_4_CLAUSE_FULL/BSD_4_CLAUSE_UCB/
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-10 16:41:19 +00:00
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.\" %%%LICENSE_START(BSD_4_CLAUSE_UCB)
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2008-06-11 21:24:46 +00:00
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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accept.2, bind.2, connect.2, getpeername.2, getpriority.2, getsockname.2, getsockopt.2, ioctl.2, killpg.2, listen.2, lseek.2, readlink.2, recv.2, send.2, setpgid.2, setreuid.2, shutdown.2, socket.2, socketpair.2, syscall.2, truncate.2, alloca.3, btree.3, daemon.3, dbopen.3, err.3, exec.3, fclose.3, ferror.3, fflush.3, fopen.3, fread.3, fseek.3, fts.3, getloadavg.3, hash.3, mpool.3, openpty.3, popen.3, queue.3, rcmd.3, recno.3, rexec.3, scanf.3, setbuf.3, stdarg.3, stdio.3, strtod.3, hostname.7, mdoc.7, mdoc.samples.7, operator.7, symlink.7: Add LICENSE_START(BSD_[34]_CLAUSE_FULL)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2013-03-10 09:28:48 +00:00
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.\" %%%LICENSE_END
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2008-06-11 21:24:46 +00:00
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.\"
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.\" @(#)hostname.7 8.2 (Berkeley) 12/30/93
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.\" $FreeBSD: src/share/man/man7/hostname.7,v 1.7 2004/07/03 18:29:23 ru Exp $
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.\"
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.\" 2008-06-11, mtk, Taken from FreeBSD 6.2 and modified for Linux.
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.\"
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execve.2, setfsgid.2, setfsuid.2, splice.2, fopen.3, malloc_trim.3, posix_memalign.3, stdarg.3, sysconf.3, tsearch.3, elf.5, hostname.7, inode.7: tstamp
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2019-05-09 07:43:09 +00:00
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.TH HOSTNAME 7 2019-05-09 "Linux" "Linux Programmer's Manual"
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2008-06-11 21:24:46 +00:00
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.SH NAME
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2008-06-27 03:37:56 +00:00
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hostname \- hostname resolution description
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2008-06-11 21:24:46 +00:00
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.SH DESCRIPTION
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Hostnames are domains, where a domain is a hierarchical, dot-separated
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2017-04-26 10:07:41 +00:00
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list of subdomains; for example, the machine "monet", in the "example"
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subdomain of the "com" domain would be represented as "monet.example.com".
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2017-04-25 13:34:58 +00:00
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Each element of the hostname must be from 1 to 63 characters long and the
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entire hostname, including the dots, can be at most 253 characters long.
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Valid characters for hostnames are
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.BR ASCII (7)
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letters from
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.I a
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to
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.IR z ,
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the digits from
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.I 0
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to
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.IR 9 ,
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and the hyphen (\-).
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A hostname may not start with a hyphen.
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2008-06-11 21:24:46 +00:00
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Hostnames are often used with network client and server programs,
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which must generally translate the name to an address for use.
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(This task is generally performed by either
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.BR getaddrinfo (3)
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or the obsolete
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.BR gethostbyname (3).)
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2019-04-23 09:11:33 +00:00
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.PP
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Hostnames are resolved by the NSS framework in glibc according
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to the
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.B hosts
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configuration in
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.BR nsswitch.conf .
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The DNS-based name resolver
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(in the
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.B dns
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NSS service module) resolves them in the following fashion.
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2008-06-11 21:24:46 +00:00
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If the name consists of a single component, that is, contains no dot,
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and if the environment variable
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.B HOSTALIASES
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is set to the name of a file,
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that file is searched for any string matching the input hostname.
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The file should consist of lines made up of two white-space separated strings,
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the first of which is the hostname alias,
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and the second of which is the complete hostname
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to be substituted for that alias.
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If a case-insensitive match is found between the hostname to be resolved
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and the first field of a line in the file, the substituted name is looked
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up with no further processing.
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2008-06-11 21:24:46 +00:00
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If the input name ends with a trailing dot,
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the trailing dot is removed,
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and the remaining name is looked up with no further processing.
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2008-06-11 21:24:46 +00:00
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If the input name does not end with a trailing dot, it is looked up
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by searching through a list of domains until a match is found.
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The default search list includes first the local domain,
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then its parent domains with at least 2 name components (longest first).
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For example,
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2017-04-26 10:07:41 +00:00
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in the domain cs.example.com, the name lithium.cchem will be checked first
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as lithium.cchem.cs.example and then as lithium.cchem.example.com.
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lithium.cchem.com will not be tried, as there is only one component
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2008-06-11 21:24:46 +00:00
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remaining from the local domain.
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The search path can be changed from the default
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by a system-wide configuration file (see
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.BR resolver (5)).
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.SH SEE ALSO
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2017-04-25 13:34:58 +00:00
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.BR getaddrinfo (3),
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2008-06-11 21:24:46 +00:00
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.BR gethostbyname (3),
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2019-04-23 09:11:33 +00:00
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.BR nsswitch.conf (5),
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2008-06-11 21:24:46 +00:00
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.BR resolver (5),
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.BR mailaddr (7),
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.BR named (8)
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2017-04-25 13:34:58 +00:00
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.UR http://www.ietf.org\:/rfc\:/rfc1123.txt
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IETF RFC\ 1123
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.UE
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aio.7, arp.7, attributes.7, boot.7, cgroups.7, cpuset.7, credentials.7, fanotify.7, fifo.7, glob.7, hier.7, hostname.7, icmp.7, inode.7, inotify.7, keyrings.7, libc.7, mailaddr.7, mount_namespaces.7, mq_overview.7, nptl.7, numa.7, path_resolution.7, persistent-keyring.7, pid_namespaces.7, pipe.7, pkeys.7, process-keyring.7, pthreads.7, pty.7, random.7, sched.7, sem_overview.7, session-keyring.7, shm_overview.7, signal-safety.7, signal.7, spufs.7, standards.7, symlink.7, termio.7, thread-keyring.7, time.7, unicode.7, user-keyring.7, user-session-keyring.7, user_namespaces.7, utf-8.7, xattr.7: ffix
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
2017-08-17 22:59:04 +00:00
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.PP
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2017-04-25 13:34:58 +00:00
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.UR http://www.ietf.org\:/rfc\:/rfc1178.txt
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IETF RFC\ 1178
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.UE
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2008-06-11 21:24:46 +00:00
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.\" .SH HISTORY
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.\" Hostname appeared in
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.\" 4.2BSD.
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