#!/bin/dash
# USAGE: erase-disk.sh <passes> <device>
# Must be run as root

echo "# Securely erasing the disk device $2"

i=1

while [ $i -le $1 ]; do
    [ $i -eq 1 ] && if="/dev/urandom" || if="/dev/zero"

    echo "\n- Begin pass $i with $if"
    dd if="$if" of="$2" status="progress"
    
    echo "- Syncing I/O"
    sync
    
    i=$(( i + 1 ))
done