BASH "Older Than" Script

older.sh

#!/bin/bash

# This script will return 0 if the specified file is older, 1 if newer than the specified date.
# Intended for use with GNU Find, like so:
#
# find filez/ -exec ./older.sh {} "2 days ago 00:00" + -delete
#
# If you want to find files that are newer than 2 days ago, you'd do something like:
#
# find filez/ -not -exec ./older.sh {} "2 days ago 00:00" + -delete
#
# Or you could change the COMPARATOR below.

COMPARATOR="-le"

function usage {
    echo "Usage: $0 <date> <file>"
    exit
}

if [ $# -ne 2 ]; then
    usage
fi

if [ -e "$1" ]; then
    FILE="$1"
    DATE="$2"
else
    if [ -e "$2" ]; then
        FILE="$2"
        DATE="$1"
    else
        usage
    fi
fi

T1=$(date --date="$(stat --printf %y "$FILE")" +%s)
T2=$(date --date="$DATE" +%s)

let "dT=$T2-$T1"

if [ $dT $COMPARATOR 0 ]; then
    exit 1
else
    exit 0
fi