{ "mode": "man", "parameter": "hosts", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/hosts/5/json", "generated": "2026-10-20T15:02:09Z", "synopsis": "", "sections": { "NAME": { "content": "hosts - static table lookup for hostnames\n", "subsections": [] }, "SYNOPSIS": { "content": "", "subsections": [ { "name": "/etc/hosts", "content": "" } ] }, "DESCRIPTION": { "content": "This manual page describes the format of the /etc/hosts file. This file is a simple text\nfile that associates IP addresses with hostnames, one line per IP address. For each host a\nsingle line should be present with the following information:\n\nIPaddress canonicalhostname [aliases...]\n\nThe IP address can conform to either IPv4 or IPv6. Fields of the entry are separated by any\nnumber of blanks and/or tab characters. Text from a \"#\" character until the end of the line\nis a comment, and is ignored. Host names may contain only alphanumeric characters, minus\nsigns (\"-\"), and periods (\".\"). They must begin with an alphabetic character and end with an\nalphanumeric character. Optional aliases provide for name changes, alternate spellings,\nshorter hostnames, or generic hostnames (for example, localhost). If required, a host may\nhave two separate entries in this file; one for each version of the Internet Protocol (IPv4\nand IPv6).\n\nThe Berkeley Internet Name Domain (BIND) Server implements the Internet name server for UNIX\nsystems. It augments or replaces the /etc/hosts file or hostname lookup, and frees a host\nfrom relying on /etc/hosts being up to date and complete.\n\nIn modern systems, even though the host table has been superseded by DNS, it is still widely\nused for:\n", "subsections": [ { "name": "bootstrapping", "content": "Most systems have a small host table containing the name and address information for\nimportant hosts on the local network. This is useful when DNS is not running, for ex‐\nample during system bootup.\n\nNIS Sites that use NIS use the host table as input to the NIS host database. Even though\nNIS can be used with DNS, most NIS sites still use the host table with an entry for\nall local hosts as a backup.\n" }, { "name": "isolated nodes", "content": "Very small sites that are isolated from the network use the host table instead of DNS.\nIf the local information rarely changes, and the network is not connected to the In‐\nternet, DNS offers little advantage.\n" } ] }, "FILES": { "content": "/etc/hosts\n", "subsections": [] }, "NOTES": { "content": "Modifications to this file normally take effect immediately, except in cases where the file\nis cached by applications.\n", "subsections": [ { "name": "Historical notes", "content": "RFC 952 gave the original format for the host table, though it has since changed.\n\nBefore the advent of DNS, the host table was the only way of resolving hostnames on the\nfledgling Internet. Indeed, this file could be created from the official host data base\nmaintained at the Network Information Control Center (NIC), though local changes were often\nrequired to bring it up to date regarding unofficial aliases and/or unknown hosts. The NIC\nno longer maintains the hosts.txt files, though looking around at the time of writing (circa\n2000), there are historical hosts.txt files on the WWW. I just found three, from 92, 94, and\n95.\n" } ] }, "EXAMPLES": { "content": "# The following lines are desirable for IPv4 capable hosts\n127.0.0.1 localhost\n\n# 127.0.1.1 is often used for the FQDN of the machine\n127.0.1.1 thishost.example.org thishost\n192.168.1.10 foo.example.org foo\n192.168.1.13 bar.example.org bar\n146.82.138.7 master.debian.org master\n209.237.226.90 www.opensource.org\n\n# The following lines are desirable for IPv6 capable hosts\n::1 localhost ip6-localhost ip6-loopback\nff02::1 ip6-allnodes\nff02::2 ip6-allrouters\n", "subsections": [] }, "SEE ALSO": { "content": "hostname(1), resolver(3), host.conf(5), resolv.conf(5), resolver(5), hostname(7), named(8)\n\nInternet RFC 952\n\nLinux man-pages 6.7 2023-10-31 hosts(5)", "subsections": [] } }, "summary": "hosts - static table lookup for hostnames", "flags": [], "examples": [ "# The following lines are desirable for IPv4 capable hosts", "127.0.0.1 localhost", "# 127.0.1.1 is often used for the FQDN of the machine", "127.0.1.1 thishost.example.org thishost", "192.168.1.10 foo.example.org foo", "192.168.1.13 bar.example.org bar", "146.82.138.7 master.debian.org master", "209.237.226.90 www.opensource.org", "# The following lines are desirable for IPv6 capable hosts", "::1 localhost ip6-localhost ip6-loopback", "ff02::1 ip6-allnodes", "ff02::2 ip6-allrouters" ], "see_also": [ { "name": "hostname", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/hostname/1/json" }, { "name": "resolver", "section": "3", "url": "https://www.chedong.com/phpMan.php/man/resolver/3/json" }, { "name": "host.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/host.conf/5/json" }, { "name": "resolv.conf", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/resolv.conf/5/json" }, { "name": "resolver", "section": "5", "url": "https://www.chedong.com/phpMan.php/man/resolver/5/json" }, { "name": "hostname", "section": "7", "url": "https://www.chedong.com/phpMan.php/man/hostname/7/json" }, { "name": "named", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/named/8/json" } ] }