Hostname in linux host

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 [-a|--alias] [-d|--domain] [-f|--fqdn|--long] [-A|--all-fqdns] [-i|--ip-address] [-I|--all-ip-addresses] [-s|--short] [-y|--yp|--nis] hostname [-b|--boot] [-F|--file filename] [hostname] hostname [-h|--help] [-V|--version] domainname [nisdomain] [-F file] ypdomainname [nisdomain] [-F file] nisdomainname [nisdomain] [-F file] dnsdomainname

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 hostname --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 effective 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 The FQDN (Fully Qualified Domain Name) of the system is the name that the resolver(3) returns for the host name, such as, ursula.example.com. It is usually the hostname followed by the DNS domain name (the part after the first dot). You can check the FQDN using hostname --fqdn or the domain name using dnsdomainname. You cannot change the FQDN with hostname or dnsdomainname. The recommended method of setting the FQDN is to make the hostname be an alias for the fully qualified name using /etc/hosts, DNS, or NIS. For example, if the hostname was "ursula", one might have a line in /etc/hosts which reads 127.0.1.1 ursula.example.com ursula 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 of the resolver (usually in /etc/host.conf) how you can change it. Usually the hosts file is parsed before DNS or NIS, so it is most common to change the FQDN 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 IP 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 localhost 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 und use hostname --all- fqdns instead wherever possible. -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, --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

FILES

/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. This file is read at boot time by the system initialization scripts to set the hostname. /etc/hosts Usually, this is where one sets the domain name by aliasing the host name to the FQDN.

AUTHORS

Peter Tobias, tobias@et-inf.fho-emden.de> Bernd Eckenfels, net-tools@lina.inka.de> (NIS and manpage). Michael Meskes, meskes@debian.org>

Источник

Как изменить Hostname (имя компьютера)

Hostname (имя компьютера, имя хоста) задается во время установки системы Linux. Hostname определяет название компьютера и используется преимущественно для идентификации компьютера в сети. Нельзя назначать два одинаковых Hostname для компьютеров в одной сети.

Просмотр текущего Hostname

Чтобы показать текущий Hostname можно использовать команду hostname без параметров:

Также Hostname можно отобразить командой hostnamectl :

Как изменить Hostname

Рассмотрим, как изменить Hostname двумя разными способами.

Способ 1. Используем команду hostnamectl

Во многих systemd-based дистрибутивах (например, в Ubuntu Linux) есть утилита hostnamectl .

Воспользуемся командой hostnamectl , чтобы установить новое значение Hostname равным pingvinus . Используется аргумент set-hostname:

sudo hostnamectl set-hostname pingvinus

Способ 2. Редактируем файлы /etc/hostname и /etc/hosts

Еще один способ изменения Hostname — это ручное редактирование файла /etc/hostname и файла /etc/hosts .

Сначала выполните команду (вместо pingvinus укажите свое значение):

Отредактируем файл /etc/hostname для редактирования в редакторе nano, выполняем команду:

Измените текущее значение в файле на новое. Сохраните изменения и закройте файл. Это можно сделать, нажав Ctrl+C , затем Y и Enter .

Hostname прописывается также в файле /etc/hosts , поэтому нужно изменить его значение в этом файле. Откроем файл:

Найдите строку вида « 127.0.0.1 ваш_hostname » и впишите новое имя хоста. Сохраните изменения и закройте файл.

Проверка результата

Чтобы проверить, изменилось ли значение Hostname, откройте новое окно терминала и введите команду:

Как временно изменить Hostname

Чтобы изменить Hostname в текущей работающей системе Linux, но до первой перезагрузки, можно использовать просто команду hostname , указав ей новое значение имени хоста:

Источник

All you need to know about hostname in Linux

The hostname is a prime identity of Linux servers in the human world! Obviously, the IP address is the main component to identify the system in the environment. In this article, we are going to see anything and everything about the hostname. We will walk through what is the hostname, how to set hostname, how to change hostname etc. Let’s start with the basics of the hostname.

What is hostname

The hostname is the humanly readable identity of the server. Any server is identified by IP address in the network but to identify easily hostname is also given. Normally FQDN (Fully Qualified Domain Name) is expected for the system but even Domain name (the name before the dot) is also fine for systems under private networks. The hostname can be alpha-numeric

Generally hostname standards to the maximum of 255 bytes long. But normally people prefer to keep it 10-12 characters long so that it’s easy to remember. Kernel variables _POSIX_HOST_NAME_MAX or HOST_NAME_MAX defines your current max limit of hostname. You can get their values using getconf a command like below :

How to set hostname in Linux

A quick command in all-new Linux distros is hostnamectl . Use set-hostname switch and your new hostname as an argument.

# hostnamectl set-hostname kerneltalks

Hostname is defined in files

/etc/hosts for networking
/etc/hostname : This will be read by boot scripts on boot time and set its value.
/proc/sys/kernel/hostname : Current hostname.
/etc/sysconfig/network : Networking (HOSTNAME=”server1″ parameter)

In above files, you can only view current hostname (being used by the live kernel) under proc file only. Rest all files are used to lookup or set hostname at boot time. So if you change hostname using hostname command then it won’t reflect in rest files. It will only reflect in the proc file.

You can set the hostname of your choice in /etc/hostname or /etc/sysconfig/network and restart network service to notify kernel about it.

How to change hostname in Linux

The current hostname can be checked by typing hostname command without any argument. The hostname can be changed by simply using hostname command followed by the name of your choice.

Cautions : Do not change hostname on live production systems!

# hostname server5 # hostname kerneltalks.com # hostname kerneltalks.com

Please make a note that change is dynamic and not permanent. After the system reboot, the hostname will be returned to what it was earlier.

Change hostname permanently in Linux

On RedHat systems : You can edit file /etc/sysconfig/network (define in HOSTNAME=”xyz”) & reboot system

# cat /etc/sysconfig/network HOSTNAME=kerneltalks.com

On Debian systems : You can edit file /etc/hostname & call /etc/init.d/hostname.sh script ( /etc/init.d/hostname.sh start )

You can even change the hostname using the system control command. Use parameter kernel.hostname and define its value like below :

# sysctl kernel.hostname=kerneltalks kernel.hostname = kerneltalks

On Suse systems : Edit file /etc/HOSTNAME and add hostname in it. There will be no parameter and value format. Only you have to enter hostname like below :

# cat /etc/HOSTNAME kerneltalks.com

Change hostname permanently in clone, template VM & cloud clones

If you have a system which is prepared using clone, template from VMware or cloud clone deploy then you should do the following :

Edit file /etc/cloud/cloud.cfg and change parameter ‘preserve_hostname’ to true. You can do it using one-line sed script as below :

root@kerneltalks # sed --in-place 's/preserve_hostname: false/preserve_hostname: true/' /etc/cloud/cloud.cfg

Also, change DHCP related parameter DHCLIENT_SET_HOSTNAME in file /etc/sysconfig/network/dhcp to no. So that hostname wont be changed by DHCP in the next reboot. Again, you can use one line sed to do that as below :

root@kerneltalks # sed --in-place 's/DHCLIENT_SET_HOSTNAME="yes"/DHCLIENT_SET_HOSTNAME="no"/' /etc/sysconfig/network/dhcp

That’s it. These are two extra steps you need to take on cloud or VM servers.

How to configure FQDN in Linux

Another thing around the hostname is to set FQDN for Linux server i.e. Fully Qualified Domain Name. Generally you should be doing in via DNS in your environment but /etc/hosts always get checked first. So its good practise to define FQDN at /etc/hosts file

Use format to add/edit entry in /etc/hosts and you are good to go. Sample entry below –

root@testsrv1 # echo "10.1.1.5 testsrv1.kerneltalks.com testsrv1">>/etc/hosts

You can verify Linux server’s FQDN by using command hostname -f

root@testsrv1 # hostname -f testsrv1.kerneltalks.com

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