# setConf(_:) Issue a `SETCONF` command to mutate Tor’s runtime configuration. ``` func setConf(_ options: [String : String?]) async throws ``` ## Parameters `options` Dictionary of torrc option names to optional string values. Pass `nil` as a value to reset. ## Discussion Composes the command body per control-spec.txt §3.1: each option with a non-`nil` value becomes `Key="Value"` (double quotes escape internal quotes); each option with a `nil` value becomes the bare `Key` form, which resets the option to its configured default. > Throws: ``doc://Tor/documentation/Tor/TorError/controlProtocolError(code:message:)`` on > rejection (e.g. reply 553 “invalid config value”). > Important: Not all torrc options are settable at runtime — > Tor rejects immutable options with reply 553. Consult > tor.1.txt for the per-option mutability annotation before > building a mutation.