VB.NET

Close a Remote SFTP File or Directory Handle

Demonstrates the Chilkat SFtp.CloseHandle method, which closes a remote file or directory handle previously returned by OpenFile or OpenDir. The only argument is the handle.

Background: Every opened handle corresponds to state the server holds, and servers cap how many a session may keep open at once, so a long-running program that forgets to close handles will eventually start failing to open new ones. Closing also ensures buffered writes are committed. Once closed, a handle is invalid and must not be reused.

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Dim success As Boolean = False

'  Demonstrates the SFtp.CloseHandle method, which closes a remote file or directory handle.  The
'  only argument is the handle returned by OpenFile or OpenDir.

Dim sftp As New Chilkat.SFtp

'  Connect, authenticate, and initialize the SFTP subsystem.
Dim port As Integer = 22
success = sftp.Connect("sftp.example.com",port)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
Dim password As String = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


success = sftp.InitializeSftp()
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


'  Open a remote file, obtaining a handle.
Dim handle As String = sftp.OpenFile("subdir/data.txt","readOnly","openExisting")
If (sftp.LastMethodSuccess = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


'  ... use the handle ...

'  Close the handle to release the server-side resource.  A handle should not be used after it
'  is closed.
success = sftp.CloseHandle(handle)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Handle closed.")

sftp.Disconnect()