Hostname is stored in /etc/hostname
file on Debian. This file is read at the boot time and name is setup using the init script /etc/init.d/hostname.sh
To make changes to the hostname, first edit this file as follows:
#sudo gedit /etc/hostname
Once you’re done editing the hostname, save the file and run the following command to set the hostname.
#sudo /etc/init.d/hostname.sh start
Now, check and confirm your hostname.