B4X

Get Received SSH Text into a StringBuilder

Demonstrates the Chilkat Ssh.GetReceivedSb method, which decodes a channel's receive buffer and appends the text to a StringBuilder. The arguments are the channel number, the charset, and the StringBuilder. The receive buffer is cleared afterward.

Background: Because this appends rather than replaces, it is the natural choice for accumulating output across repeated reads — call it in a loop and the StringBuilder grows into the complete transcript. It also avoids creating a new string on every retrieval, which matters when a command produces a large amount of text.

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Dim success As Boolean = False

'  Demonstrates the Ssh.GetReceivedSb method, which decodes the channel's receive buffer and
'  appends the text to a StringBuilder.  The 1st argument is the channel number, the 2nd is the
'  charset, and the 3rd is the StringBuilder.  The receive buffer is cleared afterward.

Dim ssh As ChilkatSsh
ssh.Initialize("ssh")

Dim sshPort As Int = 22
success = ssh.Connect("ssh.example.com", sshPort)
If success = False Then
    Log(ssh.LastErrorText)
    Return
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 = ssh.AuthenticatePw("mySshLogin", password)
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


Dim channelNum As Int = ssh.OpenSessionChannel
If channelNum < 0 Then
    Log(ssh.LastErrorText)
    Return
End If


success = ssh.SendReqExec(channelNum, "ls -l /tmp")
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


'  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
'  it, this call waits forever if the server never sends channel close.
ssh.ReadTimeoutMs = 15000

success = ssh.ChannelReceiveToClose(channelNum)
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


'  Append the received text to a StringBuilder.  Existing content is preserved.
Dim sb As ChilkatStringBuilder
sb.Initialize
success = ssh.GetReceivedSb(channelNum, "utf-8", sb)
If success = False Then
    Log(ssh.LastErrorText)
    Return
End If


Log("Characters received: " & sb.Length)
Dim output As String = sb.GetAsString
Log(output)

ssh.Disconnect