A bash script that returns the age of a file (since last change) in days

daysold.sh

#!/bin/bash

# confirm we received an argument
if [ $# -lt 1 ]
then
    echo "USAGE: bash daysold.sh <filename>"
    exit 1
fi

# confirm the argument is a file
if [ ! -f $1 ]
then
    echo "$1 does not exist"
    exit 1
fi

# calculate file age in days
NOWSECONDS=$(date +%s)
FILESECONDS=$(stat -c %Z $1)
SECONDSDIFFERENCE=$(expr $NOWSECONDS - $FILESECONDS)
DAYSDIFFERENCE=$(expr $SECONDSDIFFERENCE / 84600)

# display result
echo $DAYSDIFFERENCE

exit 0