Simple script to change the hostname permanently

[Member antixcat]

Hello all,

I found from this post:
https://www.antixforum.com/forums/topic/changing-hostname-safely/#post-100814
That there is a particular sequence of steps needed to succesfully change the hostname permanently. I have written a simple script to do this automatically for all who might find it useful:

#!/bin/bash

echo "WARNING: This script will force a logout on completion"

read -p "Enter new hostname: " new_hostname

# check if hostname is valid
pattern='^[a-zA-Z0-9\-]+$'
if ! [[ $new_hostname =~ $pattern ]]; then
	echo "Not a valid hostname"
	exit 1
fi

# get ip address from /etc/hosts
ip=$(awk 'NR==1{print $1}' /etc/hosts)

# edit /etc/hosts
# ADD the line (at line 3):
# ip-address	new_hostname
# WITHOUT removing the old hostname (at line 2):
# ip-address	current_hostname
sudo sed -i "3i\\$ip	$new_hostname" /etc/hosts

# REPLACE the only line in the file /etc/hostname
echo $new_hostname | sudo tee /etc/hostname

# again edit /etc/hosts and now REMOVE the old hostname (at line 2)
sudo sed -i '2d' /etc/hosts

# set new hostname
sudo hostname -F /etc/hostname

# logout
pkill -KILL -u $USER

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