(VB.NET) SSH Remote Shell Multiple Commands

Demonstrates how to start a shell on a remote SSH server, run a command, and retrieve the output, then run the next command, retrieve the output, etc.

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' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim ssh As New Chilkat.Ssh

' This is the prompt we'll be expecting to find in
' the output of the remote shell.
Dim myPrompt As String
myPrompt = "chilkat@ubuntu:~/workspace$"

Dim cmdOutput As String

' Connect to an SSH server:
Dim hostname As String
Dim port As Integer

' Hostname may be an IP address or hostname:
hostname = "www.some-ssh-server.com"
port = 22

Dim success As Boolean = ssh.Connect(hostname,port)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Wait a max of 10 seconds when reading responses..
ssh.IdleTimeoutMs = 10000

' Authenticate using login/password:
success = ssh.AuthenticatePw("myLogin","myPassword")
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Open a session channel.  (It is possible to have multiple
' session channels open simultaneously.)
Dim channelNum As Integer
channelNum = ssh.OpenSessionChannel()
If (channelNum < 0) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


Dim termType As String = "dumb"
Dim widthInChars As Integer = 120
Dim heightInChars As Integer = 40
' Use 0 for pixWidth and pixHeight when the dimensions
' are set in number-of-chars.
Dim pixWidth As Integer = 0
Dim pixHeight As Integer = 0
success = ssh.SendReqPty(channelNum,termType,widthInChars,heightInChars,pixWidth,pixHeight)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Start a shell on the channel:
success = ssh.SendReqShell(channelNum)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Run the 1st command in the remote shell, which will be to
'  "cd" to a subdirectory.
success = ssh.ChannelSendString(channelNum,"cd workspace" & vbCrLf,"ansi")
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Retrieve the output.
success = ssh.ChannelReceiveUntilMatch(channelNum,myPrompt,"ansi",True)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


'  Display what we've received so far.  This clears
'  the internal receive buffer, which is important.
'  After we send the command, we'll be reading until
'  the next command prompt.  If the command prompt
'  is already in the internal receive buffer, it'll think it's
'  already finished...
cmdOutput = ssh.GetReceivedText(channelNum,"ansi")
If (ssh.LastMethodSuccess <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

'  Run the 2nd command in the remote shell, which will be
'  to "ls" the directory.
success = ssh.ChannelSendString(channelNum,"ls" & vbCrLf,"ansi")
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Retrieve and display the output.
success = ssh.ChannelReceiveUntilMatch(channelNum,myPrompt,"ansi",True)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


cmdOutput = ssh.GetReceivedText(channelNum,"ansi")
If (ssh.LastMethodSuccess <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)


'  Start the final command in the remote shell.  This example
'  will send a "ls -l" command to retrieve the long format directory listing.
success = ssh.ChannelSendString(channelNum,"ls -l" & vbCrLf,"ansi")
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If



' Send an EOF.  This tells the server that no more data will 
' be sent on this channel.  The channel remains open, and
' the SSH client may still receive output on this channel.
success = ssh.ChannelSendEof(channelNum)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Read whatever output may already be available on the
' SSH connection.  ChannelReadAndPoll returns the number of bytes
' that are available in the channel's internal buffer that
' are ready to be "picked up" by calling GetReceivedText
' or GetReceivedData.
' A return value of -1 indicates failure.
' A return value of -2 indicates a failure via timeout.

' The ChannelReadAndPoll method waits
' for data to arrive on the connection usingi the IdleTimeoutMs
' property setting.  Once the first data arrives, it continues
' reading but instead uses the pollTimeoutMs passed in the 2nd argument:
' A return value of -2 indicates a timeout where no data is received.
Dim n As Integer
Dim pollTimeoutMs As Integer = 2000
n = ssh.ChannelReadAndPoll(channelNum,pollTimeoutMs)
If (n < 0) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Close the channel:
success = ssh.ChannelSendClose(channelNum)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


' Perhaps we did not receive all of the commands output.
' To make sure,  call ChannelReceiveToClose to accumulate any remaining
' output until the server's corresponding "channel close" is received.
success = ssh.ChannelReceiveToClose(channelNum)
If (success <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If


cmdOutput = ssh.GetReceivedText(channelNum,"ansi")
If (ssh.LastMethodSuccess <> True) Then
    Debug.WriteLine(ssh.LastErrorText)
    Exit Sub
End If

Debug.WriteLine(cmdOutput)

' Disconnect
ssh.Disconnect()