filldisk function

filldisk(){
DISKNUM=$2 
if [[ ! $2 =~ [0-9] ]]; then echo must specify disk num as 2nd arg;return 1;fi
SKIP="${3:-0}"
BS="${4:-4}"
SIZE=$(( (2 * 1024 *1024) - ($SKIP * 1024) ))
gnumfmt --format=%.3f --to=iec --from=iec ${SIZE}M\

case $1 in
random)
SOURCE='/usr/local/Cellar/openssl/1.0.2k/bin/openssl enc -aes-128-cbc -pass pass:$(dd if=/dev/urandom bs=128 count=1 2>/dev/null | base64) -nosalt < /dev/zero'
;;
zeros)
SOURCE='dd if=/dev/zero'
;;
*)
echo 'Must specify "random" or "zeros" as first arg.'
return 1 
esac
eval $SOURCE\
|pv --progress --eta --rate --bytes --size ${SIZE}m\
|dd of=/dev/rdisk$DISKNUM bs=${BS}m seek=$((($SKIP * 1024)/$BS))
}