#!/bin/bash
 #We can work out if the day of the week with date +%a Mon Tue Wed Thu Fri Sat Sun
 DAY=$(date +%a)
 FILE=data
 SNAR=${FILE}.snar
 TAR=~/${FILE}.${DAY}.tar.gz
 
 #If it is Monday we need to make sure that we start with a new snar file to ensure full #backup
 #If the snar file is there it is renamed with a date extension of the previous Monday
 if [ $DAY = 'Mon' ]
   then
    test -e ~/$SNAR && mv $SNAR ${SNAR}.$(date --date '7 days ago' +%F)
 fi
 tar -czg ~/$SNAR -f $TAR ~/$FILE