[Linux] What is the host name confirmation method other than the hostname command?

Introduction

When I posted an article like this the day before yesterday, thankfully the response was great. [Linux] Why do I, an infrastructure engineer, not use the "hostname" command?

In this article, I would like to introduce how to check the host name other than the hostname command on Linux.

How to check the host name other than the hostname command

uname -n

ʻUname` is a command that displays system information.

You can display the host name by adding the -n option to this command.

command

uname -n

Execution result

[root@tspdev01 ~]# uname -n
tspdev01
[root@tspdev01 ~]#

hostnamectl status

This is a host name confirmation command that can be used on Linux 7 series (RHEL / CentOS).

command

hostnamectl status

Execution result

[root@tspdev01 ~]# hostnamectl status
   Static hostname: tspdev01
         Icon name: computer-vm
           Chassis: vm
        Machine ID: 4ac15a471f30914187be09916857cdb9
           Boot ID: bedcdc6861c34bc5881a2ddb91c7955c
    Virtualization: kvm
  Operating System: CentOS Linux 7 (Core)
       CPE OS Name: cpe:/o:centos:centos:7
            Kernel: Linux 3.10.0-1127.13.1.el7.x86_64
      Architecture: x86-64
[root@tspdev01 ~]#

echo $HOSTNAME

You can check the host name by checking the value of the variable HOSTNAME.

command

echo $HOSTNAME

Execution result

[root@tspdev01 ~]# echo $HOSTNAME
tspdev01
[root@tspdev01 ~]#

[Extra edition] Create a test user and execute "hostname i".

Let's verify if the host name is ʻi`.

The OS is here.

OS version

[dev@tspdev01 ~]$ cat /etc/redhat-release
CentOS Linux release 7.8.2003 (Core)
[dev@tspdev01 ~]$

1. User created

Create a dev user.

command

useradd -m dev

Execution example

[root@tspdev01 ~]# useradd -m dev
[root@tspdev01 ~]#

2. Set a password for the created user

Set a password for the dev user.

command

passwd dev

Execution example

[root@tspdev01 ~]# passwd dev
Change password for user dev.
new password:
Please re-enter your new password:
passwd:All authentication tokens have been successfully renewed.
[root@tspdev01 ~]#

3. Switch to dev user

Switch from the root user to the dev user.

command

su - dev

Execution example

[root@tspdev01 ~]# su - dev
[dev@tspdev01 ~]$

4. Execute hostname i.

Execution result

[dev@tspdev01 ~]$ hostname i
hostname: you must be root to change the host name
[dev@tspdev01 ~]$

** As a result, the root user was asked and could not be modified. ** **

Summary

** ○ Host name confirmation command other than the hostname command **

• uname -n
• hostnamectl status
• echo $HOSTNAME

** ○ What happens if I enter hostname i as a general user? ** **

Root privileges were required and the host name could not be changed.

Reference article

Variable HOSTNAME 6.3. Hostname configuration using HOSTNAMECTL Actually easy! How to create and add Linux users