HowTo: open older Pi SD card via USB multi-reader on Raspberry Pi

After doing

sudo apt-get update

sudo apt-get upgrade

on an older Raspbian installation (at a 4GB SD Card), some corruption occured (probably due to lack of space, since I see newer NOOBS asks for an 8GB SD Card), making it unbootable. Would only show the NOOBS splash screen, but couldn’t boot into Raspbian.

I just needed some audio files from the desktop of that older installation (it was an unattended looping audio player for an art installation).

So I prepared a new SD Card with the free SD Card Formatter utility and put the latest NOOBS files in it. Booted the Raspberry Pi 2 with it and installed the latest Raspbian OS (full) from the menus. This time doing again the above two commands from a terminal and rebooting didn’t cause any problem.

However, I was searching for the files and couldn’t find them. I had gotten a bit confused at first, since when plugging in the reader it would show a dialog asking whether I wanted to open a file explorer, but then it would keep that dialog again and repeat the action till I closed the dialog. Then I read

…in Linux when there are more slots in a card reader, only the one labelled LUN 0 is read unless other tools are installed to read the other luns. If your SD slot is not LUN 0, then the SD card will not be seen.There are a lot of pages on web about this, I will be installing a package called sg3-utils that is supposed to enable reading other card reader slots.

at this thread https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=11397 and just in case I did:

sudo apt-get install sg3-utils

from a terminal and then tried plugging in again the USB card reader with the older SD card.

This time I was patient and instead of closing the action dialog that was shown after executing the suggested action (open with file explorer), I repeated it for three times and respective file explorer windows came up, then the action dialog closed by itself. The three windows were showing different partitions that had been found in the SD card, and one of those windows was showing “/media/pi/” folder. I navigated from there to “root/home/pi/Desktop” subfolder, where I could see the old desktop contents and drag-drop the audio files I was looking for to the new desktop.