If your refrigerator is gone, how long is a newly opened can of food good for, since it was sterile until opened?

Less than overnight: If refrigerator is broken and the inside temperature is same as the room temperature, the newly opened can would soon become near or at the room temperature. It is advised that you consume the food within the same day.

Depends on food and: container. It is difficult to sterilize a can opener, so bacteria are often introduced when cutting into a can, in contrast to a container that has a separate screw top lid. Secondly, Foods that have are highly acidic such as dressings with vinegar or ketchup, will have a longer unrefrigerated life. It is generally recommended to refrigerate within 2 hours. See this for food spoilage: http://www.partselect.com/JustForFun/Food-Spoilage-Chart.aspx

Food: Depends on what kind of food was in the can. For instance, canned nuts will last longer than canned milk.

Depends on the: type of food, ambient air temperature, if the food is covered and possibly more.