| Long: preproxy | 
 | Arg: [protocol://]host[:port] | 
 | Help: Use this proxy first | 
 | Added: 7.52.0 | 
 | --- | 
 | Use the specified SOCKS proxy before connecting to an HTTP or HTTPS --proxy. In | 
 | such a case curl first connects to the SOCKS proxy and then connects (through | 
 | SOCKS) to the HTTP or HTTPS proxy. Hence pre proxy. | 
 |  | 
 | The pre proxy string should be specified with a protocol:// prefix to specify | 
 | alternative proxy protocols. Use socks4://, socks4a://, socks5:// or | 
 | socks5h:// to request the specific SOCKS version to be used. No protocol | 
 | specified will make curl default to SOCKS4. | 
 |  | 
 | If the port number is not specified in the proxy string, it is assumed to be | 
 | 1080. | 
 |  | 
 | User and password that might be provided in the proxy string are URL decoded | 
 | by curl. This allows you to pass in special characters such as @ by using %40 | 
 | or pass in a colon with %3a. | 
 |  | 
 | If this option is used several times, the last one will be used. |