ADDR2NAME(1) User's Manual ADDR2NAME(1)NAME
addr2name, name2addr - perform DNS lookups from scripts
SYNOPSIS
addr2name [-46cmnr] [HOSTNAMES]
name2addr [-46cn] [HOSTNAMES]
DESCRIPTON
Write addresses or canonical hostname of specified names to the standard output. If no names are specified via the command line, they are
read from the standard input.
OPTIONS -4 or --ipv4
Only try to perform IPv4 lookups.
-6 or --ipv6
Only try to perform IPv6 lookups.
-c or --config
Only lookup and print results for address families that match locally configured addresses (If the system has no IPv4 resp IPv6
address, then IPv4 resp IPv6 addresses are ignored).
-h or --help
Display some help and exit.
-m or --multiple
Normally, if a name yields multiple results, only the first one is printed. With this optional parameter, all results will be
printed on a single line, separated by spaces.
-n or --numeric
Prevent forward hostname lookup. This ensures that the input names are numeric addresses, which do not need to be looked up. Typi-
cally used along with the --reverse option to convert numerical addresses to canonical hostnames.
-r or --reverse
Perform a reverse DNS lookup (enabled implicitly with addr2name). addr2name prints numerical resolved addresses by default instead.
--version
Display program version and license and exit.
SEE ALSO host(1), getaddrinfo(3), getnameinfo(3), resolv.conf(5)AUTHOR
Remi Denis-Courmont <remi at remlab dot net>
$Id: addr2name.1 658 2010-10-31 20:56:30Z remi $
http://www.remlab.net/ndisc6/
addr2name $Date: 2010-10-31 22:56:30 +0200 (dim. 31 oct. 2010) $ ADDR2NAME(1)
Check Out this Related Man Page
HOSTNAME(1) Linux Programmer's Manual HOSTNAME(1)NAME
hostname - show or set the system's host name
domainname - show or set the system's NIS/YP domain name
ypdomainname - show or set the system's NIS/YP domain name
nisdomainname - show or set the system's NIS/YP domain name
dnsdomainname - show the system's DNS domain name
SYNOPSIS
hostname [-v] [-a|--alias] [-d|--domain] [-f|--fqdn|--long] [-A|--all-fqdns] [-i|--ip-address] [-I|--all-ip-addresses] [-s|--short]
[-y|--yp|--nis]
hostname [-v] [-b|--boot] [-F|--file filename] [hostname]
hostname [-v] [-h|--help] [-V|--version]
domainname [nisdomain] [-F file]
ypdomainname [nisdomain] [-F file]
nisdomainname [nisdomain] [-F file]
dnsdomainname [-v]
DESCRIPTION
Hostname is used to display the system's DNS name, and to display or set its hostname or NIS domain name.
GET NAME
When called without any arguments, the program displays the current names:
hostname will print the name of the system as returned by the gethostname(2) function.
domainname will print the NIS domainname of the system. domainname uses the gethostname(2) function, while ypdomainname and nisdomainname
use the yp_get_default_domain(3).
dnsdomainname will print the domain part of the FQDN (Fully Qualified Domain Name). The complete FQDN of the system is returned with host-
name --fqdn (but see the warnings in section THE FQDN below).
SET NAME
When called with one argument or with the --file option, the commands set the host name or the NIS/YP domain name. hostname uses the
sethostname(2) function, while all of the three domainname, ypdomainname and nisdomainname use setdomainname(2). Note, that this is effec-
tive only until the next reboot. Edit /etc/hostname for permanent change.
Note, that only the super-user can change the names.
It is not possible to set the FQDN or the DNS domain name with the dnsdomainname command (see THE FQDN below).
The host name is usually set once at system startup in /etc/init.d/hostname.sh (normally by reading the contents of a file which contains
the host name, e.g. /etc/hostname).
THE FQDN
You can't change the FQDN (as returned by hostname --fqdn) or the DNS domain name (as returned by dnsdomainname) with this command. The
FQDN of the system is the name that the resolver(3) returns for the host name.
Technically: The FQDN is the name getaddrinfo(3) returns for the host name returned by gethostname(2). The DNS domain name is the part
after the first dot.
Therefore it depends on the configuration (usually in /etc/host.conf) how you can change it. Usually (if the hosts file is parsed before
DNS or NIS) you can change it in /etc/hosts.
If a machine has multiple network interfaces/addresses or is used in a mobile environment, then it may either have multiple FQDNs/domain
names or none at all. Therefore avoid using hostname --fqdn, hostname --domain and dnsdomainname. hostname --ip-address is subject to the
same limitations so it should be avoided as well.
OPTIONS -a, --alias
Display the alias name of the host (if used). This option is deprecated and should not be used anymore.
-A, --all-fqdns
Displays all FQDNs of the machine. This option enumerates all configured network addresses on all configured network interfaces, and
translates them to DNS domain names. Addresses that cannot be translated (i.e. because they do not have an appropriate reverse DNS
entry) are skipped. Note that different addresses may resolve to the same name, therefore the output may contain duplicate entries.
Do not make any assumptions about the order of the output.
-b, --boot
Always set a hostname; this allows the file specified by -F to be non-existant or empty, in which case the default hostname local-
host will be used if none is yet set.
-d, --domain
Display the name of the DNS domain. Don't use the command domainname to get the DNS domain name because it will show the NIS domain
name and not the DNS domain name. Use dnsdomainname instead. See the warnings in section THE FQDN above, and avoid using this
option.
-f, --fqdn, --long
Display the FQDN (Fully Qualified Domain Name). A FQDN consists of a short host name and the DNS domain name. Unless you are using
bind or NIS for host lookups you can change the FQDN and the DNS domain name (which is part of the FQDN) in the /etc/hosts file. See
the warnings in section THE FQDN above, and avoid using this option; use hostname --all-fqdns instead.
-F, --file filename
Read the host name from the specified file. Comments (lines starting with a `#') are ignored.
-i, --ip-address
Display the network address(es) of the host name. Note that this works only if the host name can be resolved. Avoid using this
option; use hostname --all-ip-addresses instead.
-I, --all-ip-addresses
Display all network addresses of the host. This option enumerates all configured addresses on all network interfaces. The loopback
interface and IPv6 link-local addresses are omitted. Contrary to option -i, this option does not depend on name resolution. Do not
make any assumptions about the order of the output.
-s, --short
Display the short host name. This is the host name cut at the first dot.
-v, --verbose
Be verbose and tell what's going on.
-V, --version
Print version information on standard output and exit successfully.
-y, --yp, --nis
Display the NIS domain name. If a parameter is given (or --file name ) then root can also set a new NIS domain.
-h, --help
Print a usage message and exit.
NOTES
The address families hostname tries when looking up the FQDN, aliases and network addresses of the host are determined by the configuration
of your resolver. For instance, on GNU Libc systems, the resolver can be instructed to try IPv6 lookups first by using the inet6 option in
/etc/resolv.conf.
FILES
/etc/hosts
/etc/hostname Historically this file was supposed to only contain the hostname and not the full canonical FQDN. Nowadays most software is
able to cope with a full FQDN here.
AUTHORS
Peter Tobias, <tobias@et-inf.fho-emden.de>
Bernd Eckenfels, <net-tools@lina.inka.de> (NIS and manpage).
Michael Meskes, <meskes@debian.org>
net-tools 2009-09-16 HOSTNAME(1)