How to change default login action Url to xyz/login Url

How to change default login action Url to xyz/login Url

I am newbie for yii. I have created my separate login page in my
controller. Here my question is "When session expires it will ask for
re-login. and it will transfer to site/login page.
Instead of site/login I want to redirect it to xyz/login page. Where I
have to change this?
Please suggest me.