BASH script to write zeros to file before remove | Use for non-secure HDD

rmzero.sh

#!/bin/bash
# use find exec to remove multiple files:
#   find path/to/dir -exec ./rmzero {} \;

if [ "$#" -lt 1 ]; then
        echo "./`basename $0` <file>";
        exit 1;
fi

function load() { FILE="$(realpath $1)" ; MB_COUNT="$(du -m $FILE | awk '{print $1}')" ; }
function main() { dd if=/dev/zero of="$FILE" bs=1M count=$MB_COUNT ; rm $FILE ; }

load "$@" &>/dev/null

if [ -f "$FILE" ]; then
        main &>/dev/null &
else
    	echo "$FILE is not a file."
fi