How to check key signature in linux?

Question

linux

I read the manual and there:
Download the repository's gpg key, check it (it has been signed with my own GPG key
)

Answer 1

gpg --no-default-keyring --keyring /path/to/pubkey.gpg --verify /path/to/file.txt.gpg

Answer 2

If there is GPG, read the GPG manual. The operation is typical and should be described.