FTP Reply Code

A three-digit status code returned by the FTP server after every client command, structured similarly to HTTP status codes. The first digit indicates the outcome class: 1xx (positive preliminary — action in progress), 2xx (positive completion), 3xx (positive intermediate — more information needed), 4xx (transient negative — retry may succeed), and 5xx (permanent negative — command not accepted). The remaining digits narrow the specific meaning within each class.