FTP custom commands

##Remarks libcURL can be used to send arbitrary FTP command sequences before and/or after an FTP transfer completes. This can be used to, for example, delete remote files or send server-specific setup or tear-down commands. The general idea is to tell libcURL to perform a headers-only transfer on a FTP directory URL. libcURL will establish the FTP session, CWD into the remote directory specified in the URL, and then execute any custom commands.

Commands are formatted as a linked list of strings which will be passed verbatim to the server. Use the ListPtr class to construct the list:

  Dim lst As New libcURL.ListPtr
  Call lst.Append("CWD public_html")
  Call lst.Append("MKD old")
  Call lst.Append("RNFR index.html")
  Call lst.Append("RNTO old/index.html")

You then pass the list to EasyHandle.SetOption with option numbers libcURL.Opts.QUOTE, libcURL.Opts.PREQUOTE, or libcURL.Opts.POSTQUOTE.

##Examples ###FTP delete This example deletes a file from a FTP server. This is accomplished by telling libcURL to do a directory listing of the remote parent directory (URL path ends in a / indicating a directory; NOBODY is True) and sending custom FTP commands after the transfer finishes (i.e. the commands specified by POSTQUOTE).

  Dim Server As String = "ftp://ftp.example.com/directory/subdirectory/"
  Dim RemoteFile As String = "file.bin"
  Dim curl As New cURLClient
  Dim cmds As New libcURL.ListPtr
  Call cmds.Append("DELE " + RemoteFile)
  Call curl.SetOption(libcURL.Opts.POSTQUOTE, cmds)
  If Not curl.Head(Server) Then ' HEAD a directory = CWD directory
    MsgBox(libcURL.FormatError(curl.LastError))
  End If

###FTP rename This example renames the remote file by sending the RNFR and RNTO FTP verbs.

  Dim Server As String = "ftp://ftp.example.com/directory/subdirectory/"
  Dim RemoteFile As String = "file.bin"
  Dim NewName As String = "file2.bin"
  Dim curl As New cURLClient
  Dim cmds As New libcURL.ListPtr
  Call cmds.Append("RNFR " + RemoteFile) ' Rename-From
  Call cmds.Append("RNTO " + NewName) ' Rename-To
  Call curl.SetOption(libcURL.Opts.POSTQUOTE, cmds)
  If Not curl.Head(Server) Then ' HEAD a directory = CWD directory
    MsgBox(libcURL.FormatError(curl.LastError))
  End If