linux下hostname查看

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好记性不如烂笔头

man hostname

NAME
       hostname - show or set the system’s host name
       domainname - show or set the system’s NIS/YP domain name
       dnsdomainname - show the system’s DNS domain name
       nisdomainname - show or set system’s NIS/YP domain name
       ypdomainname - show or set the system’s NIS/YP domain name

SYNOPSIS
       hostname  [-v]  [-a]  [--alias]  [-d] [--domain] [-f] [--fqdn] [-A] [--all-fqdns] [-i] [--ip-address] [-I] [--all-ip-addresses] [--long] [-s] [--short] [-y] [--yp]
       [--nis]

       hostname [-v] [-F filename] [--file filename] [hostname]

       domainname [-v] [-F filename] [--file filename] [name]

       nodename [-v] [-F filename] [--file filename] [name]

       hostname [-v] [-h] [--help] [-V] [--version]

       dnsdomainname [-v]
       nisdomainname [-v]
       ypdomainname [-v]

DESCRIPTION
       Hostname is the program that is used to either set or display the current host, domain or node name of the system.  These names are used by many of the  networking
       programs to identify the machine. The domain name is also used by NIS/YP.

   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,  nisdomainname,  ypdomainname  will  print the name of the system as returned by the getdomainname(2) function. This is also known as the YP/NIS domain
       name of the system.

       dnsdomainname will print the domain part of the FQDN (Fully Qualified Domain Name). The complete FQDN of the system is returned with hostname --fqdn.

       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 gethost-
       name(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/sysconfig/network or /etc/hosts

       To add another dimension to this, the hostname is also set when the network interface is brought up.

   SET NAME
       When called with one argument or with the --file option, the commands set the host name, the NIS/YP domain name or the node name.

       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/rc.d/rc.inet1 or /etc/init.d/boot (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 gethostbyname(2) 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).

       -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.

       -F, --file filename
              Read the host name from the specified file. Comments (lines starting with a ‘#’) are ignored.

       -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.

       -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.

       -h, --help
              Print a usage message and exit.

       -i, --ip-address
              Display the IP address(es) of the host. 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  out-
              put.

       -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.

       -v, --verbose
              Be verbose and tell what’s going on.

       -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.

FILES
       /etc/hosts /etc/sysconfig/network

NOTE
       Note that hostname doesn’t change anything permanently. After reboot original names from /etc/hosts are used again.

 

查看 /etc/sysconfig/network

[andrew@andrew test_c_lang]$ vim /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=andrew

示例 gethostname()

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>


int main(int argc,char **argv)
{
        int z;
        char buf[256];
        z = gethostname(buf,sizeof buf);
        if(z==-1)
        {   
                fprintf(stderr,"%s:gethostname(2)\n",strerror(errno));
                exit(EXIT_FAILURE);
        }   
        printf("host name = '%s'\n",buf);
        z = getdomainname(buf,sizeof buf);
        if(z==-1)
        {   
                fprintf(stderr,"%s:getdomainname(2)\n",strerror(errno));
                exit(EXIT_FAILURE);
        }   
        printf("domain name = '%s'\n",buf);
        return EXIT_SUCCESS;
}

运行结果：

[andrew@andrew test_c_lang]$ ./test_gethostname 
host name = 'andrew'
domain name = '(none)'

 

转载于:https://my.oschina.net/u/2326611/blog/850496