There are native programs available on Android for creating file systems, and in most cases they reside in a directory below
/system (my Motorola Droid 2 e.g. has them in
/system/xbin. Depending on the file system you want to create, you can chose between:
mkfs.minix (unlikely you want that -- and it might even be not available with your ROM)
As the latter is probably what you want, some closer explanation on its options here:
mkfs.vfat [-v] [-n LABEL] BLOCKDEV [KBYTES]
What do those options stand for?
-v: Generate verbose output (reporting)
-n Label: Give the file system a name
BLOCKDEV: the file system you want to format
KBYTES: probably the block size (I'm not 100% sure with this)
So the minimal thing to do would be:
mkfs.vfat -v /dev/block/uba1
(provided your drive to format is available as
/dev/block/uba1 on your system). One more example, giving the file system a name:
mkfs.vfat -v -n MyNewDisk /dev/block/uba1
It should report success then -- or an error if it failed.
EDIT: On some systems, the
mkfs commands seem to be part of the
busybox binaries -- which you can recognize with a full directory listing, e.g.
ls -l /system/xbin | grep mkfs
It should show them as "symbolic links" pointing to busybox then. In this case, you can optionally run them via busybox:
should show you the syntax then (thanks to ce4 for pointing this out -- credits to him ;) ).