There are some USB commands still to be gotten working correctly, one of those is rename. So far there is no example of it in Sony's CONNECT software so I'm having to figure the command out by trying various things.
Another is "How much space is left". Unix doesn't grok composite file systems. The mountable filesystem looks like one filesystem to Unix but is actually two filesystems on the Sony Reader with two different amounts of available storage space: two pegs one hole to put a peg into.
