findfakes

#!/bin/sh
# Finds fake files (e.g. those files which are 700mb big, but contain just zeros)
# by bramp.net 2015
#
if [ -z "$1" ]; then
    echo "Usage: $0 <directory/files>"
    echo "List files that are fakes"
    return
fi
for path in "$@"
do
    find "$path" -type f | while read file; do
        if [ -s "$file" ]; then
            # If file is non-zero bytes, check if the actual content of the file is all zeros
            cmp "$file" /dev/zero -n `stat -c "%s" "$file"` -s;
            if [ $? -eq 0 ]; then
                echo "$file"
            elif [ $? -eq 2 ]; then
                echo Error reading "$file"
            # else files are different, ignore
            fi
        fi
    done
done