[Linux]常用命令之【hostname】

1: 个人的片面理解: hostname是主机名（的"昵称"），而非域名。一般设置hostname，来标识当前机器的主要用途、以区别与其它机器

2: hostname的严格定义: Hostname用于显示系统的DNS名称，以及显示或设置系统的主机名或NIS域名。

Hostname is used to display the system's DNS name, and to display or set its hostname or NIS domain name.

1 查看 hostname

• 方法1: hostname

hostname

2 修改 hostname

• 方法1: hostnamectl
  
  无需重启只需新开会话便可变为新的主机名.

hostnamectl set-hostname 新的主机名

• 方法2: hostname
  
  无需重启只需新开会话便可变为新的主机名.

hostname 新主机名

• 方法3: /etc/hostname

vi /etc/hostname
    node116 编辑主机名

vi /etc/sysconfig/network
  192.168.1.116 node116 # 添加IP和hostname对应关系

reboot
   重启后生效

3 hostname命令详解

# man hostname
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 [-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).

       The function gethostname(2) is used to get the hostname.  When the hostname -a, -d, -f or -i is called will gethostbyname(3) be called.  The  difference  in  gethostname(2)
       and  gethostbyname(3) is that gethostbyname(3) is network aware, so it consults /etc/nsswitch.conf and /etc/host.conf to decide whether to read information in /etc/hostname
       or /etc/hosts

   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 (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 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 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, 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, --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
his 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>

X 参考文献

• Centos7修改主机名hostname的三种方法 - jb51.net