File privileges problem on USB thumbdrive

[Colin Law]

On Sun, 16 Aug 2020 at 20:10, Bret Busby <bret.busby at gmail.com> wrote:
>
> Hello.
>
> This applies equally to UbuntuMATE 20.04.x and 16.04.x .
>
> I have a USB thumbdrive, which is formatted as FAT32.
>
> I want to move the files written to it, to another medium, so as to
> reuse the thumbdrive for writing.
>
> I have previously done this, with this thumbdrive, and, with other
> thumbdrives of the same model, capacity (128GB), and manufacturer.
>
> However, now, whilst file managers (caja and PCmanFM) show me, as the
> owner of the files, with Read and write folder access, no file access
> privilege is shown in the caja file manager, and, I can not use cut
> (and thence paste to another destination) or rename functionality on
> the files, and, trying to use chmod 777 and sudo chmod 777 , both
> return the error "file system is read only".
>
> ls  -l shows
> -rw -r--r--
> for the files.
>
> As I am supposed to be able, as the shown owner of the files, both
> read and write to, the files, why does the operating system designate
> them as read-only, and, how do I overcome this?

Apologies in advance, but I have to ask whether you have checked that
the write protect switch on the drive (if there is one) is in the
correct state?

Otherwise are you able to write to it on a Windows system?  It is
possible that it is broken.

It might be worth watching the log while you plug it in, it might
indicate why it is read only.
sudo journalctl -f
or
sudo tail -f /var/log/syslog

Colin