Thomas Chang wrote:But I use the followings and it works.
It may work in some cases, but it is highly dependent on the value. If the values have no spaces (or other special characters), it can work. If the values have spaces it will break.
If you don't understand why, you should get a book on UNIX Shell Programming, as it will cover how to set environment variables, and why you need to quote them. For now, if you want it to work all the time, you need to do as Peter said. It is the only correct way to do it.