busybox combines what are generally separate files into a single executable

apt-cache in a shell can be used to search for packages and apt-get install to install them.

Nokia-N800-36-5:~# which fdisk
Nokia-N800-36-5:~# apt-cache search fdisk
cfdisk - curses based disk drive partitioning program
Nokia-N800-36-5:~# apt-cache search mkdosfs
dosfstools - Utilities to create and check MS-DOS FAT filesystems