fdns.sh - upserts blocks of hosts into /etc/hosts

fdns.sh

#!/bin/bash
set -e
set -x

FDNS_HOSTS_FILE=${1:-.fdns}

FDNS_HOSTS_KEY=$(echo $FDNS_HOSTS_FILE | sed 's/[^a-zA-Z0-9]//g')

echo updating $FDNS_HOSTS_KEY block

FDNS_MARKER_START='^###---FDNS-START-'"${FDNS_HOSTS_FILE}"'---###$'
FDNS_MARKER_END='^###---FDNS-END-'"${FDNS_HOSTS_FILE}"'---###$'

if [[ -z ${FDNS_HOSTS_FILE} || ! -f ${FDNS_HOSTS_FILE} ]]; then
  echo "hosts file not provided or missing: got $FDNS_HOSTS_FILE"
  exit 1
fi

if grep -q ${FDNS_HOSTS_FILE} /etc/hosts; then
    sudo sed -i -e "/${FDNS_MARKER_START}/,/${FDNS_MARKER_END}/{ /$FDNS_MARKER_START/{p; r ${FDNS_HOSTS_FILE}
         }; /$FDNS_MARKER_END/p; d }"  /etc/hosts
else
    sudo bash -c "echo '"${FDNS_MARKER_START:1:${#FDNS_MARKER_START}-2}"' >> /etc/hosts"
    sudo bash -c "cat "${FDNS_HOSTS_FILE}" >> /etc/hosts"
    sudo bash -c "echo '"${FDNS_MARKER_END:1:${#FDNS_MARKER_END}-2}"' >> /etc/hosts"
fi