#!/bin/bash
LON="8° 02' 41.9\"W"
LAT="39° 57' 00.0\"N"

deg_to_dec() 
{
    deg=$(echo "$@"|awk -F\° '{ print $1 }')
    ARG=$(echo "$@"|awk -F\° '{ print $2 }')
    min=$(echo "$ARG"|awk -F\' '{ print $1 }')
    ARG=$(echo "$ARG"|awk -F\' '{ print $2 }')
    sec=$(echo "$ARG"|awk -F\" '{ print $1 }')

    operation="scale=10; ( $deg + $min / 60 + $sec / 3600 )"

    echo $ARG|grep -ioE "[ws]$" >/dev/null && operation="$operation * -1"
    bc <<< "$operation"
}

echo "` deg_to_dec $LAT `:` deg_to_dec $LON `"