How can I get hidden files from an external device with terminal?

Question

Here is my situation. I have an mp3 player that is a Sansa Clipp.  This version has third party firmware installed that not only hides the music files but will not let me copy them at all when I do a straight copy.  All I get are empty folders.  I want to install the actual firmware but first I need to back up the entire contents of the device because essentially I need to wipe the malicious firmware and everything else off the disc in order to to this. This device came from the Bureau of Prisons and is sold to prisoners.  It is basically locked to the hilt and the only way to unlock it officially is to send it to the third party that installed the firmware and pay them $25.  I know that I should be able to use terminal to get the files off of this but so far a  "cp" command has only given me the files that I get when I drag and drop.  The music files seem to be hidden in a partition that I can't access.  Let me know if anyone has any help they can give.  I just need to back up the full contents of the device.  I have instructions on how to wipe it and reinstall but backing up is crucial to this.  Thanks for any help and please ask questions if I haven't made my problem clear enough.

Answer 1

I have know way of knowing whether or not this will copy the data. The device could have some hidden hand-shack.
I assume the Sansa Clipp is a usb connected device.  The method works for a flash drive.  There is a different method for a harddrive..
First, you need to find the name of the device.  Mount the device.
/Applications/Utilities/Terminal.
# run the df command.  type command then press return.
mac $ df -h
Filesystem                Size   Used  Avail Capacity  Mounted on
/dev/disk1s16             272G   259G    12G    95%    /
devfs                     113K   113K     0B   100%    /dev
fdesc                     1.0K   1.0K     0B   100%    /dev
<volfs>                   512K   512K     0B   100%    /.vol
automount -nsl [217]        0B     0B     0B   100%    /Network
automount -fstab [222]      0B     0B     0B   100%    /automount/Servers
automount -static [222]     0B     0B     0B   100%    /automount/static
/dev/disk1s10             500G   302G   197G    60%    /Volumes/ServiceRepairManuals
/dev/disk1s14              80G    50G    30G    62%    /Volumes/Second-80
/dev/disk2s1              446M    15M   431M     3%    /Volumes/2partitions
/dev/disk2s2               46M   9.0M    37M    20%    /Volumes/second-disk
mac $ # unmount disk by dragging to trash can.
mac $ df -h
Filesystem                Size   Used  Avail Capacity  Mounted on
/dev/disk1s16             272G   259G    12G    95%    /
devfs                     112K   112K     0B   100%    /dev
fdesc                     1.0K   1.0K     0B   100%    /dev
<volfs>                   512K   512K     0B   100%    /.vol
automount -nsl [217]        0B     0B     0B   100%    /Network
automount -fstab [222]      0B     0B     0B   100%    /automount/Servers
automount -static [222]     0B     0B     0B   100%    /automount/static
/dev/disk1s10             500G   302G   197G    60%    /Volumes/ServiceRepairManuals
/dev/disk1s14              80G    50G    30G    62%    /Volumes/Second-80
mac $ # figure out the name of the device.
mac $ # see what dev disappeared.
mac $ # in this case the unix names of the partitions are: /dev/disk2s1 & dev/disk2s2
mac $ # the device, flash name, is /dev/disk2
mac $ # pull out the device from it's usb port.  Plug it back in.
mac $ df -h
Filesystem                Size   Used  Avail Capacity  Mounted on
/dev/disk1s16             272G   259G    12G    95%    /
devfs                     113K   113K     0B   100%    /dev
fdesc                     1.0K   1.0K     0B   100%    /dev
<volfs>                   512K   512K     0B   100%    /.vol
automount -nsl [217]        0B     0B     0B   100%    /Network
automount -fstab [222]      0B     0B     0B   100%    /automount/Servers
automount -static [222]     0B     0B     0B   100%    /automount/static
/dev/disk1s10             500G   302G   197G    60%    /Volumes/ServiceRepairManuals
/dev/disk1s14              80G    50G    30G    62%    /Volumes/Second-80
/dev/disk2s1              446M    15M   431M     3%    /Volumes/2partitions
/dev/disk2s2               46M   9.0M    37M    20%    /Volumes/second-disk
mac $ dd if=/dev/disk2 bs=4096 | gzip | dd of=~/disk2-s1-2 bs=4096
dd: /dev/disk2: No such file or directory
0+1 records in
0+1 records out
20 bytes transferred in 0.014734 secs (1357 bytes/sec)
mac $