Type Command
Category Generation 
Command /#fill
Help Use /help #fill

This command fills the area completely with any block - also random compositions of metadata.

Use --shape sphere to fill in the shape of a sphere or circle instead.

Note that this also functions as a replace command by offering the second parameter (positioned block expression), e.g. to replace stone with dirt:

/#fill dirt stone

to fill a selected region with spruce planks (note: need to enter meta data tag):

/#fill minecraft:planks --m 1

--flood <directions> Edit

This command floods the material around it with any block. This is useful for filling unusual shapes with a kind of block, for example lakes or houses. By default, all air blocks are flooded, but this can be modified by providing a source block expression parameter.