Are disaccharides linked via an ester linkage?

No, disaccharides are not linked via ester linkages; they are connected by glycosidic bonds. A glycosidic bond is formed between the hydroxyl group of one monosaccharide and the anomeric carbon of another, resulting in the release of a water molecule through a dehydration reaction. This linkage is distinct from ester linkages, which involve the reaction between an alcohol and a carboxylic acid.