create/delete a ramdisk on mac

mount_ramdisk.sh

#!/bin/sh

# 只要執行 mount_ramdisk.sh 就會建立一個 4GB 的 RAM disk，
# 執行 mount_ramdisk.sh 2 就會建立一個 2GB 的 RAM disk，
# 執行 mount_ramdisk.sh -u 就可以卸載掉 RAM disk： 

RAM_DISK_GB=4
RAM_DISK_NAME=RamDisk
MOUNTED_RAM_DISK_FOLDER="/Volumes/${RAM_DISK_NAME}"
# Unmount RAM disk
if [ "$1" = "-u" ]; then
    if [ -e "${MOUNTED_RAM_DISK_FOLDER}" ]; then
hdiutil detach "${MOUNTED_RAM_DISK_FOLDER}"
else
echo "RAM disk is not mounted yet."
fi
exit
fi
# Get RAM disk size from parameter
if [ "$1" != "" ]; then
RAM_DISK_GB="$1"
fi
if [ -e "${MOUNTED_RAM_DISK_FOLDER}" ]; then
echo "RAM disk is already mounted on ${MOUNTED_RAM_DISK_FOLDER}."
else
diskutil erasevolume HFS+ "${RAM_DISK_NAME}" $(hdiutil attach -nomount ram://$((RAM_DISK_GB*1024*2048)))
fi