# Opens up the manual page for the command 'hostnamectl'
man hostnamectl

# Shows current host-name/OS/Kernel/Architecture/chasis/machineID/BootID/Icon-name fields. 
$ sudo hostnamectrl

# Example output:

   Static hostname: Server-machine-name
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: 
           Boot ID: 
  Operating System: elementary OS 5.1.4 Hera
            Kernel: Linux 4.15.0-99-generic
      Architecture: x86-64

# Set a new Hostname.
$ sudo hostnamexctl set-hostname 

# No output is succesful.
# You could check '$?' is 0 for success