Replace gpg with gpg2 if/as needed.

Cheatsheet

List a key, previously imported

$ gpg --list-keys <keyid>

Import public key

$ gpg --import <path to public key file>

Verify file signature

$ gpg --verify <signature-file> <signed-file>

Display public key details without importing

$ gpg --with-fingerprint <path to public key file>

You may also search the key in a keyserver for further comparison/verification

$ gpg --search-keys <key id>
<Press Q to avoid importing key>