FTP Commands: RMDA-XRMD-REST-RNFR-RNTO-THMB

The RMDA command allows clients to perform a recursive delete operation a directory using a single command. Typically deleting a directory with many subdirectories and files will force the user to wait for the client to issue DELE and RMD commands to each file and directory, preventing the user from doing any work until the operations are completed. Issuing the RMDA command unloads that operation to the server, allowing the client to continue working unhindered.

Common responses:

• 250
• 501, 550

The XDEL deletes the specified directory on the server, and is a duplicate of the RMD command. It is implemented because some firewalls assume that all FTP characters must be 4 characters in length.

Common responses:

• 250
• 501, 550

The REST command is used to specify a marker to the server for the purposes of resuming a file transfer . Issuing the REST command does not actually initiate the transfer. After issuing a REST command, the client must send the appropriate FTP command to transfer the file. The server will use the marker specified in the REST command to resume file transfer at the specified point.

Common responses:

• 350
• 421
• 500, 501, 502, 530

The RNFR command is issued when an FTP client wants to rename a file on the server. The client specifies the name of the file to be renamed along with the command. After issuing an RNFR command, an RNTO command must immediately follow.

Common responses:

• 350
• 421, 450
• 500, 501, 502, 530, 550

The RNTO command is used to specify the new name of a file specified in a preceding RNFR (Rename From) command.

Common responses:

• 250
• 421
• 500, 501, 502, 503, 530, 532, 553

The THMB command allows clients to view a small thumbnail copy of an image before downloading the full image. When the THMB command is issued, the server dynamically generates thumbnails of the specified size and sends the images to the client, using far less bandwidth than would be necessary to send the whole image.

Common responses:

• 150
• 226
• 425, 426, 450
• 501, 550

• RETR FTP command
• EPSV FTP command
• USER FTP command
• CDUP FTP command
• MFMT FTP command
• NLST FTP command
• PROT FTP command