Shell Programming and Scripting

# get the domain name
read -r thehostname < /etc/hostname
dom="$(echo $thehostname | cut -d'.' -f2)"
numchar=${#dom}
if [ "$numchar" -le 5 ]
then
echo "It appears as though the hostname is not correctly set."
echo "Hostname has $thehostname as your hostname." 
echo "Please enter the domain name"
read realdom
dom=$realdom
thehostname="svr.$realdom.com"
sed -i 1c"$thehostname" /etc/hostname
fi

$ echo "domain.com" >hostname
$ cat hostname 
domain.com
$ cat script.sh
#!/usr/bin/env bash

thehostname="svr.domain.com"
sed -i 1c"$thehostname" ./hostname
$ bash script.sh
$ cat hostname 
svr.domain.com
$