title: External USB storage on Android
body: <p>I'm writing small media player for Android on DigiBoard(Evaluation Board). I want to use USB storage for playing music. I can plug USB, my board mount it(I see a notification) and when I use ADB shell and go to /mnt/ i have several folders, one of them is udisk and SD Card:</p>
  
  <pre><code># cd mnt
  cd mnt
  # ls
  ls
  obb
  shm
  asec
  extsd
  udisk
  sdcard
  secure
  </code></pre>
  
  <p>I'm listing a proc/mounts content:</p>
  
  <pre><code># cat mounts
  cat mounts
  rootfs / rootfs rw 0 0
  ubi0_0 / ubifs rw,relatime 0 0
  tmpfs /dev tmpfs rw,relatime,mode=755 0 0
  devpts /dev/pts devpts rw,relatime,mode=600 0 0
  proc /proc proc rw,relatime 0 0
  sysfs /sys sysfs rw,relatime 0 0
  tmpfs /mnt/asec tmpfs rw,relatime,mode=755,gid=1000 0 0
  tmpfs /mnt/obb tmpfs rw,relatime,mode=755,gid=1000 0 0
  tmpfs /mnt/shm tmpfs rw,relatime,size=1024k,mode=775,uid=1000,gid=1003 0 0
  /dev/block/vold/179:1 /mnt/sdcard vfat ro,dirsync,nosuid,nodev,noexec,relatime,u
  id=1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset
  =iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
  /dev/block/vold/179:1 /mnt/secure/asec vfat ro,dirsync,nosuid,nodev,noexec,relat
  ime,uid=1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,ioch
  arset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
  tmpfs /mnt/sdcard/.android_secure tmpfs ro,relatime,size=0k,mode=000 0 0
  /dev/block/vold/8:1 /mnt/udisk vfat rw,dirsync,nosuid,nodev,noexec,relatime,uid=
  1000,gid=1015,fmask=0002,dmask=0002,allow_utime=0020,codepage=cp437,iocharset=is
  o8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
  #
  </code></pre>
  
  <p>I have here some paths, two of them are "valid" mnt/sdcard  and mnt/udisk. I've read that entries with vfat are valid mounts, but /mnt/secure/asec have vfat property. I have application named ES File Explorer and I can see files in "udisk" folder:
  <img src="https://i.stack.imgur.com/3CEiQ.jpg" alt="EZ output">
  so it is possible to filter mounted sources. Can you tell me how to filter this? Are some folders in /mnt by default and i can list them/hardcode in app so I'll check their names?</p>