This is a tiny tool to copy songs from hard drive to udisk. It randomly copies mp3 files and writes a checkpoint file after it's done. Next time it runs, it reads checkpoint file and copy different mp3 files. (You'll need to delete the old files from your udisk manually.)

User manual

$ cd go
$ GOPATH=`pwd` go install copy_mp3
$ ./bin/copy_mp3 -src-dir=XXX -dst-dir=YYY