if i take my 4 pot calipers off my car how do i stop the brake fluid coming out of the pipe at the back of the calipers thanks

 

Clamp it so you dont have to bleed the system (make sure air tight)... although if your changing the brakes probs best to bleed it just to be on the safe side

 

you can buy little clamps that pinch the rubber sections of the feed pipes to the calipers. you can buy them from halfords or a good motor spares shop for about a tenner.
Just remember to take them off after you've fitted your new calipers!!!!!!!!!!!!!!!!!
oh and definately bleed the system once all of the above is done too.