Delete_all_files_before_a_given_date

#!/bin/bash

if [ $# -eq 0 ]
then
        echo "Usage: ./script.sh directory_path date[optional]"
        echo "date should be in proper format e.g. 20180506 for 6th May, 2018"
        echo "In the absence of date, all files older than 15 days from today will be deleted in the given directory otherwise all files older than the given date will be deleted"
        exit 1
fi


input_directory=$1
echo "input_directory: $input_directory"

days_in_year=365
days_in_month=30
backup_duration_in_days=15

if [ $# -eq 2 ]
then
        echo "no. of parameters are 2"
        reference_date=$2

else
        reference_date=$(date +"%Y%m%d")  # = 20130718
fi

##################### Getting reference date in proper format ###########################

mod_reference_date=$(echo $reference_date|awk '{print substr($1,1,4)}')
mod_reference_date=$((mod_reference_date * days_in_year))

temp=$(echo $reference_date|awk '{print substr($1,5,2)}')
temp=${temp#0}
temp=$((temp*days_in_month))

mod_reference_date=$((mod_reference_date+temp))

if [ $# -eq 1 ]
then
        mod_reference_date=$((mod_reference_date+temp-backup_duration_in_days))
fi

echo "mod_reference_date: $mod_reference_date"

#################### Function for getting file's last modification date in proper format ####################

file_date()
{
        file_date=$(stat $1|awk -F': ' '/Modify: /{print $2}'|awk '{print $1}'|sed 's/-//g')    # = 20130715
        mod_file_date=$(echo $file_date|awk '{print substr($1,1,4)}')
        mod_file_date=$((mod_file_date * days_in_year))

        temp=$(echo $file_date|awk '{print substr($1,5,2)}')
        temp=$((temp*days_in_month))
        temp=${temp#0}

        mod_file_date=$((mod_file_date+temp))
        temp=$(echo $file_date|awk '{print substr($1,7,2)}')
        temp=${temp#0}

        mod_file_date=$((mod_file_date+temp))
        echo " Inside function $1: $mod_file_date"
        if [ $mod_file_date -lt $mod_reference_date ]
        then
                rm -rf $2/$1
        fi
}

for i in $( ls $input_directory);
do
        file_date $i $input_directory
done