#!/usr/bin/env bash

# Author        : Allan Christensen
# First Created : 05012022 (DD-MM-YYYY)
# Description   : Installs Ntp client on Ubuntu 24.04
# License       : MIT License (see LICENSE file for details)

#
# Are we root
#
if [[ $(id -u) -ne 0 ]]; then echo "" && echo "Must be root or use sudo" && echo ""; exit 1; fi

#
# Install and enable NTP
#
apt install -y ntp ntpdate && systemctl enable ntp

#
# Disable systemd-timesyncd NTP
#
timedatectl set-ntp off

#
# Sync time once
#
ntpdate -u 0.pool.ntp.org

#
# Determine which NTP config file to use
#
# Default NTP config file
conf_file="/etc/ntp.conf"

#
# If ntpsec is installed, override with ntpsec's config file
#
if [ -f /etc/ntpsec/ntp.conf ]; then conf_file="/etc/ntpsec/ntp.conf" ; fi

#
# Backup existing config file
#
backup_file="${conf_file}.bak"; cp "$conf_file" "$backup_file"

# 
# Define NTP servers
# 
ntp_servers="server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
server 3.pool.ntp.org"

#
# Comment out existing pool servers
#
sed -i '/pool.ntp.org/ s/^/# /g' "$conf_file"

#
# Add the new defined servers
tmp_file="/tmp/ntpconf" ; printf "%s\n" "$ntp_servers" > "$tmp_file"

# Insert after a line containing "Specify one" if it exists else append at the end
if grep -q "Specify one" "$conf_file"; then
    sed -i "/Specify one/r $tmp_file" "$conf_file"
else
    cat "$tmp_file" >> "$conf_file"
fi

#
# Restart NTP service
#
systemctl restart ntp

#
# Clean up
#
rm -f "$tmp_file"

#
# All done
#
printf "\nAll Done...\n"

#
# End of script
#