How should I encrypt a file using gpg linux command with PGP public key?
I have searched on google and I found this command
gpg --output doc.gpg --encrypt --recipient blake@cyb.org doc
but I didn't find where to keep the public key in the command.
If, as you said, you already have a key file, then you need to gpg --import that key into your keyring.
After that, you can gpg --list-keys to see the email address that you have to use as the argument to --recipient.