Visual Basic 6.0

Get the Exit Status of a Remote SSH Command

Demonstrates the Chilkat Ssh.GetChannelExitStatus method, which returns the remote process exit status for a channel. The only argument is the channel number. Call it only after ChannelReceivedExitStatus returns true.

Background: The exit status is how you learn whether a remote command actually succeeded — recall that a successful exec request only means the request was accepted. By Unix convention 0 means success and any nonzero value indicates a failure. Retrieve it promptly after the receive operation and before calling unrelated SSH methods or releasing the channel, since the completed channel record can be discarded.

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Visual Basic 6.0

Dim success As Long
success = 0

'  Demonstrates the Ssh.GetChannelExitStatus method, which returns the remote process exit
'  status for a channel.  The only argument is the channel number.  Call it only after
'  ChannelReceivedExitStatus returns 1.

Dim ssh As New ChilkatSsh

Dim sshPort As Long
sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
If (success = 0) Then
    Debug.Print ssh.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
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

Dim channelNum As Long
channelNum = ssh.OpenSessionChannel()
If (channelNum < 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

success = ssh.SendReqExec(channelNum,"grep -q root /etc/passwd")
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
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 = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  Retrieve the exit status immediately, before calling unrelated SSH methods or releasing the
'  channel, because the completed channel record can be discarded.
If (ssh.ChannelReceivedExitStatus(channelNum)) Then
    Dim exitStatus As Long
    exitStatus = ssh.GetChannelExitStatus(channelNum)
    Debug.Print "Exit status: " & exitStatus

    '  By convention, 0 means the remote command succeeded.
    If (exitStatus = 0) Then
        Debug.Print "The remote command succeeded."
    Else
        Debug.Print "The remote command reported a failure."
    End If

End If

ssh.Disconnect