rarp

#!/usr/bin/env bash
# reverse arp

USAGE='
Example:
rarp 00:0a:95:9d:68:16
=> 192.168.0.253
'

abort() {
  [[ $# -gt 0 ]] && echo "$@"
  echo "$USAGE" 1>&2
  exit 1
}

IS_VERBOSE=false

while getopts hxv option; do
  case $option in
    x) set -x;;
    v) IS_VERBOSE=true;;
    h|\?) abort;;
  esac
done
[[ $OPTIND -gt 1 ]] && shift $((OPTIND - 1))

[[ $# -lt 1 ]] && abort "MAC address not found"

[[ $(echo "$1" | tr ":" "\n" | wc -l) -ne 6 ]] && abort "invalid MAC address: $1"

MAC=$(sed -e "s/^0//" -e "s/:0/:/g" <<< "$1")

if OUTPUT=$(arp -an | grep "$MAC"); then
  if $IS_VERBOSE; then
    echo "$OUTPUT"
  else
    awk '{print $2}' <<< "$OUTPUT" | tr -d "()"
  fi
else
  echo "not found ip address of $MAC" 2>&1
fi