is there a way to check the is there a way to check the hard drive for errors with ubuntu?

is there a way to check the hard drive for errors with ubuntu? Windows used to have "scan disk." How do you check what the partitions are on a hard drive. I'm asking b/c i only have 5 g of free space, and its a 20 g hard drive, and i put all my photos and things on a data disk so its not taking up space.