hostname.sh

#!/bin/bash
# Changes your machine's hostname
# Usage: bash <(wget -O - http://git.io/Kbt8oQ) MY_HOSTNAME
# 

old=$(hostname)
new=$1

# Backup old hosts file
date=$(date +%F_%T | sed 's/:/-/g')
sudo cp /etc/hosts{,.backup-$date}

# Set hosts file with both old and new hostname
sudo bash -c "cat > /etc/hosts" <<EOF
127.0.0.1   localhost
127.0.1.1   $new	# Current Hostname
127.0.1.1	$old	# Previous Hostname

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF

# Set hostname
sudo bash -c "cat > /etc/hostname" <<EOF
$new
EOF

# Reload hostname
sudo service hostname start

# Set hosts file with only new hostname
sudo bash -c "cat > /etc/hosts" <<EOF
127.0.0.1   localhost
127.0.1.1   $new

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
EOF

echo "Hostname changed to: $new"
echo "Reboot recommended"