Fdisk
From FreeBSDwiki
fdisk' is the system command used in FreeBSD and other unixlike OSes to handle partitioning hard drives. (See also disklabel for editing disk slices.) Along with disklabel, this fdisk provides roughly analogous functionality to the same-named Windows command fdisk.
See also sysinstall for accomplishing all hard drive partitioning, slicing, and formatting tasks inside a convenient text-mode GUI.