encrypt file in batch mode

[Fourhundred Thecat]

On 02/11/2019 22.52, Brian C via Gnupg-users wrote:
> I can answer why the passphrase is needed: You are using the -s option
> which tells gpg to sign the file, which requires your private key.

You are right. It works when I remove "-s".

But it makes no sense. This particular private key has no passphrase. So
shouldn't signing work in batch mode as well ?

Also, I still get an error when trustdb.gpg is not writable.

I am specifically using "--no-auto-check-trustdb" and "--lock-never",
but these options do not seem to have any effect.

Here is full syntax I am using now:

gpg --no-auto-check-trustdb --lock-never --no-verbose --batch --yes
--pinentry-mode loopback -e -r user at domain.com -o zz.gpg zz

The above works, if trustdb.gpg is writable. It fails if it is not:

gpg: Fatal: can't open '/var/lib/asterisk/.gnupg/trustdb.gpg': Operation
not permitted

Why does gpg need trustdb.gpg to be writable? I am not asking to change
any trust settings. I just need simply to encrypt file.

thanks,