decrypt file in batch mode

[Fourhundred Thecat]

Hello,

I have a file which has been encrypted with a symmetric cipher (using a
passphrase).

How can I decrypt this file in batch mode, without gpg-agent ?

$ gpg --lock-never --no-verbose --batch --yes -d zz.gpg

gpg: AES256 encrypted data
gpg: failed to start agent '/usr/bin/gpg-agent': No such file or directory
gpg: can't connect to the agent: No such file or directory
gpg: problem with the agent: No agent running
gpg: encrypted with 1 passphrase
gpg: decryption failed: No secret key

Why does gpg look for secret key ?
This is symmetric encryption. What does it need secret key for ?

Any way to circumvent this ?

thanks,