With the --supported command the caller can test whether a site supports the Web Key Service. The argument is an arbitrary address in the to be tested domain. For example 'firstname.lastname@example.org'. The command returns success if the Web Key Service is supported. The operation is silent; to get diagnostic output use the option --verbose. See option --with-colons for a variant of this command.
With the --check command the caller can test whether a key exists for a supplied mail address. The command returns success if a key is available.
The --create command is used to send a request for publication in the Web Key Directory. The arguments are the fingerprint of the key and the user id to publish. The output from the command is a properly formatted mail with all standard headers. This mail can be fed to sendmail(8) or any other tool to actually send that mail. If sendmail(8) is installed the option --send can be used to directly send the created request. If the provider request a 'mailbox-only' user id and no such user id is found, gpg-wks-client will try an additional user id.
The --receive and --read commands are used to process confirmation mails as send from the service provider. The former expects an encrypted MIME messages, the latter an already decrypted MIME message. The result of these commands are another mail which can be send in the same way as the mail created with --create.
The command --install-key manually installs a key into a local directory (see option -C) reflecting the structure of a WKD. The arguments are a file with the keyblock and the user-id to install. If the first argument resembles a fingerprint the key is taken from the current keyring; to force the use of a file, prefix the first argument with "./". If no arguments are given the parameters are read from stdin; the expected format are lines with the fingerprint and the mailbox separated by a space. The command --remove-key removes a key from that directory, its only argument is a user-id.
The command --print-wkd-hash prints the WKD user-id identifiers and the corresponding mailboxes from the user-ids given on the command line or via stdin (one user-id per line).
The command --print-wkd-url prints the URLs used to fetch the key for the given user-ids from WKD. The meanwhile preferred format with sub-domains is used here.
gpg-wks-client is not commonly invoked directly and thus it is not installed in the bin directory. Here is an example how it can be invoked manually to check for a Web Key Directory entry for 'email@example.com':
$(gpgconf --list-dirs libexecdir)/gpg-wks-client --check firstname.lastname@example.org
gpg-wks-client understands these options: