On Monday 09 December 2019 at 22:38:26, Hendrik Boom wrote:

> I have an sd card that used to be in an android phone.
> My usual tools tell me very little:
>
> root@midwinter:~# lsblk --fs /dev/sdb
> NAME FSTYPE LABEL UUID MOUNTPOINT
> sdb
> ├─sdb1
> └─sdb2
>
> root@midwinter:~# fdisk -l /dev/sdb
> Disk /dev/sdb: 14.9 GiB, 15931539456 bytes, 31116288 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: gpt
> Disk identifier: 4F1502F0-81F3-49FA-A294-8B8FB4DB6964

I'm really rather surprised that a 16Gbyte SD card is has a GPT partition
table.

> Device     Start      End  Sectors  Size Type
> /dev/sdb1   2048    34815    32768   16M unknown
> /dev/sdb2  34816 31116254 31081439 14.8G unknown
> root@midwinter:~#

>
> Is there another way to find out anything?

Well, given that it's got a GPT partition table, try sgdisk instead of sfdisk.

> Or is this likely to be an Google-encrypted card I can do nothing with
> except restore it to an almost virginal state?

What do you *want* to do with it?

Read it, copy it, reformat it, what?

> And what is the proper way to reformat an sdcard to the file
> systems just about everything accepts without using
> up its remaining lifetime?

Hm, dd if=/dev/zero of=/dev/sdb bs=1M count=1

That should blow away the existing partition table and let you start from
scratch with sfdisk again.


Antony.

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