Bash date loop

date_loop.sh

#! /bin/bash

date_start="2015-01-01"
date_end="2015-12-31"

date_start_unixtime="`date --date="$date_start" +"%s"`"
date_end_unixtime="`date --date="$date_end" +"%s"`"

date_current=$date_start
date_current_unixtime=$date_start_unixtime

echo $date_current_unixtime - $date_end_unixtime

while [ "$date_current_unixtime" -le "$date_end_unixtime" ]; do
    date +"%d.%m.%Y" -d "$date_current"

    date_current="`date +"%Y-%m-%d" -d "$date_current + 1 DAY"`"
    date_current_unixtime="`date --date="$date_current" +"%s"`"
done