Create a RAM disk for using with XCode, with Umount disks method

xcode_ramdisk.sh

#!/bin/sh
# Create a RAM disk with same perms as mountpoint
# Script based on http://itux.idev.pro/2012/04/iservice-speed-up-your-xcode-%D0%BD%D0%B5%D0%BA%D0%BE%D1%82%D0%BE%D1%80%D1%8B%D0%B5-%D1%81%D0%BF%D0%BE%D1%81%D0%BE%D0%B1%D1%8B/ with some additions
# Usage: sudo ./xcode_ramdisk.sh start

USERNAME=$(logname)

DEV_CACHES_DIR="/Users/$USERNAME/Library/Developer/Xcode/DerivedData"
DEV_CACHES_SHADOW_DIR="/Users/$USERNAME/Library/Developer/Xcode/DerivedData_shadow"

RAMDisk() {
	mntpt="$1"
	rdsize=$(($2*1024*1024/512))

	# Create the RAM disk.
	dev=`hdiutil attach -nomount ram://$rdsize`
	# Successfull creation...
	if [ $? -eq 0 ] ; then
		# Create HFS on the RAM volume.
		newfs_hfs $dev

		# Store permissions from old mount point.
		eval `/usr/bin/stat -s "$mntpt"`
		# Mount the RAM disk to the target mount point.
		mount -t hfs -o union -o nobrowse -o nodev -o noatime $dev "$mntpt"
		# Restore permissions like they were on old volume.
		chown $st_uid:$st_gid "$mntpt"
		chmod $st_mode "$mntpt"
		
		echo "Creating RamFS for $mntpt $rdsize $dev"
	fi
}

UmountDisk() {
	mntpt="$1"
	dev=`mount | grep "$mntpt" | grep hfs | cut -f 1 -d ' '`
	umount -f "$mntpt"
	hdiutil detach "$dev"
	echo "Umount RamFS for $mntpt $dev"
	echo ""
}

# Test for arguments.
if [ -z $1 ]; then
echo "Usage: $0 [start|stop|restart] "
exit 1
fi

# Source the common setup functions for startup scripts
test -r /etc/rc.common || exit 1 
. /etc/rc.common

StartService () {
	ConsoleMessage "Starting RamFS disks..."

	RAMDisk "$DEV_CACHES_DIR" 4096
	cp -rp "$DEV_CACHES_SHADOW_DIR/"* "$DEV_CACHES_DIR/"
}

StopService () {
	if [ "$(pgrep Xcode$)" ]; then
		ConsoleMessage "Xcode is running, i'm going close it first."
		kill -15 `pgrep Xcode$`		
	fi
	if [ $? -eq 0 ] ; then
		ConsoleMessage "Stopping RamFS disks..."
		/usr/bin/rsync -aqr --delete "$DEV_CACHES_DIR/" "$DEV_CACHES_SHADOW_DIR/"
		UmountDisk "$DEV_CACHES_DIR"
	fi
}

RestartService () {
	ConsoleMessage "Restarting RamFS disks..."
	StopService
	StartService
}

RunService "$1"