I am following the instructions for this, but the first step, editing sources.list goes wrong.
My sources.list only contains one line, saying it was installed from a CD...
What next?

Richard

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perhaps worth to try this:
gpg --keyserver keyring.debian.org --recv-keys 6669378035F4918C


On 29/06/2020 21:29, Pete Goodeve wrote:
> On Mon, Jun 29, 2020 at 09:04:34PM +0200, Richard van Bemmelen wrote:
>> Thanks, I tried that, but when doing sudo apt-get update I got the
>> following error:
>>
>> W: GPG error: http://apt.gka.thinkglobally.org stretch InRelease: The
>> following signatures couldn't be verified because the public key is not
>> available: NO_PUBKEY 6669378035F4918C
>> E: The repository 'http://apt.gka.thinkglobally.org stretch InRelease' is
>> not signed.
>> N: Updating from such a repository can't be done securely, and is therefore
>> disabled by default.
>> N: See apt-secure(8) manpage for repository creation and user configuration
>> details.
>>
>> did you get that too?
>> Richard
> 
> I don't remember any such problem, I'm afraid.  As the haze on my memory
> lifts slightly, I think I started building 6.12 around March last year,
> which is when the file was apparently edited.
> 
> That apt-secure man page has quite a lot of information, but it doesn't
> leave me much the wiser on first reading! (:-/) I wonder if I have a
> different security setting somewhere, or something?
> 
> Sorry I can't be of more help.  I think there's a Mint forum somewhere,
> which might give clues?
> 
> 	-- Pete --
> 
>>
>> Op ma 29 jun. 2020 om 20:02 schreef Pete Goodeve >> :
>>
>>> On Mon, Jun 29, 2020 at 06:18:20PM +0100, Richard (Zappfinger) van
>>> Bemmelen wrote:
>>>> I am following the instructions for this, but the first step, editing
>>> sources.list goes wrong.
>>>> My sources.list only contains one line, saying it was installed from a
>>> CD...
>>>> What next?
>>>>
>>> Not a definitive answer, but I was able to build Csound 6.14 on Mint
>>> a few months back, and my sources.list has -- after the header comment:
>>>
>>> deb http://apt.gka.thinkglobally.org/ stretch main
>>> deb-src http://apt.gka.thinkglobally.org/ stretch main
>>>
>>> 'stretch' I guess being the Debian equivalent of my Mint 'Sonya'.
>>> I don't remember, but it looks from the date as if I did edit the file,
>>> probably to add that second line.
>>>
>>>          -- Pete --
>>>
> 
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> 

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apt-key is the tool used to add to the OS package trust store

https://askubuntu.com/questions/291035/how-to-add-a-gpg-key-to-the-apt-sources-keyring

the installer process usually defines online repos as part of the
initial install of a debian based system, and there's likely a wizard
or tool for wrapping up parts of the installation or re-running needed
tasks

On Mon, Jun 29, 2020 at 1:15 PM Pete Goodeve  wrote:
>
> On Mon, Jun 29, 2020 at 10:08:22PM +0200, Richard van Bemmelen wrote:
> > Yes, I have this file, but it is binary, can't make sense of it....
> >
> Me neither...  And the docs are quite impenetrable, so I'm totally
> in the dark.  It needs someone who knows about this stuff.  Sorry.
>
>         -- Pete --
>
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