FTP programming guide for VB programmers 1.6-server feedback

 

Question: Server feedback Lecture: qianqian

Server feedback After sending the FTP command, you will receive a response from the server. The response information consists of three digits, spaces, and text. Figure 7 lists some response information. For the complete description, see RFC 959. Figure 7 return values. 110 re-start Mark response (restart marker reply ). it shows that Mark yyyy = mmmm YYYY is the mark of the data stream processed by the user, while mmmm is the corresponding mark of the server (note the space between Mark and "= ). 120 the service is ready within NNN minutes. 125 the data connection is enabled; transmission starts. 150 File status OK; data connection to be opened. the 200 command OK .202 is not implemented and is redundant on this site. 211 system status or response to system help. 212 directory status. 213 File status. 214 help information. 215 name system type. 220 the service is ready for new users. 221 close the Service Control connection. if appropriate, launch logon. 225 data connection is enabled, and no data is being transferred. 226 close the data connection. the required file operation is complete .. 227 enters passive mode (H1, H2, H3, H4, P1, P2 ). 230 user login, handled. 250 file operation OK, complete. 257 "pathname" has been created. 331 user name OK, password required. 332 You need to log on to the account. 350 file operation latency and further information. 421 the service is unavailable. Disable the control connection. this reply may apply to any directory when the service must be closed. 425 unable to open the data connection. 426 Connection closed; transmission exception aborted. 450 file operations are not accepted. the file is unavailable (for example, the file is busy ). 451 the operation is aborted; a local error occurs during processing. 452 operation not accepted. insufficient system storage space. 500 syntax error. The command cannot be identified. it may include errors such as too long commands. 501 parameter syntax error. 502 command not implemented. 503 command order error. 504 this parameter command is not implemented. 530 not logged on. 532 accounts are required to store files. 550 the required operation is not accepted. the file is unavailable (for example, the file is not found ). 551 the operation is aborted abnormally. The page type is unknown. 552 the operation is aborted abnormally. the storage space is exceeded (for the current directory or dataset ). 553 the required operation is not accepted. the file name is not allowed. Return Value category Each return value has a special meaning. The first number has five values: 1 indicates a positive, preliminary answer (this command is accepted, and this is the first part of the affirmative answer from other servers ); 2 indicates a permanent affirmative answer; 3 indicates a medium-level affirmative answer. In this case, the server is waiting for further information; 4 indicates that the command is not accepted, the required operation does not appear. This may be temporary; 5 indicates an absolute failure. The second number indicates the type of the answer: 0 indicates a syntax error; 1 indicates information content; 2 indicates information about the transmission link; 3 indicates verification or account information; 4 indicates not used; 5 indicates information about the file system status. The third number further classifies the error. Figure 8 shows a brief review of how to analyze FTP Response values. For more information, see RFC 959. Figure 8 explains the FTP return value. 1xx affirmative preliminary answer 2XX affirmative answer 3xx affirmative intermediate answer 4xx short answer completion answer 5xx permanent negative answer x0x syntax error x1x information x2x connection x3x verification and account x4x x5x file system not specified (Keep this information for sorting and reprinting thousands of VB sites)