Shell script to mount a disk on RAM with a specific name and size on Mac OS X

ram.sh

#!/bin/bash
#
# Create a virtual disk on RAM with a given name and size.
# To remove it, just unmount it in Finder.
#
# Usage: ram.sh <name> <size in MB>
#

function usage() {
	echo "$0 <name> <size in MB>"
}

if [[ $# -lt 2 ]]; then
	usage
	exit 1
fi

if ! [[ $2 =~ ^[0-9]+$ ]]; then
    echo "size must be a numeric value" >&2
	exit 1
fi

name=$1
size=$2
device=$(hdiutil attach -nobrowse -nomount ram://$(($size*2048)))
diskutil erasevolume HFS+ $name $device