(C#) SSH -- Running Commands that Prompt for Additional Input, such as "su"

Demonstrates how to run a shell command via SSH where the shell command prompts for additional input from the client. This example demonstrates "su".

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

Chilkat.Ssh ssh = new Chilkat.Ssh();

// Hostname may be an IP address or hostname:
string hostname = "172.16.16.46";
int port = 22;

bool success = ssh.Connect(hostname,port);
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// If receiving output from a command stalls for more than 5 seconds, then stop waiting.
ssh.IdleTimeoutMs = 5000;

success = ssh.AuthenticatePw("myLogin","myPassword");
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Open a session channel. 
int channelNum = ssh.OpenSessionChannel();
if (channelNum < 0) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Request a pseudo-terminal
string termType = "dumb";
int widthInChars = 120;
int heightInChars = 40;
int pixWidth = 0;
int pixHeight = 0;
success = ssh.SendReqPty(channelNum,termType,widthInChars,heightInChars,pixWidth,pixHeight);
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Start a shell on the channel:
success = ssh.SendReqShell(channelNum);
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Send the su command.
// (The SSH server I'm using for testing is a Linux Ubuntu
// system running OpenSSH.  It is important in this case to send a bare-LF
// and not a CRLF.)
string cmd = "su\n";
success = ssh.ChannelSendString(channelNum,cmd,"ansi");
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Read until we get the prompt for the password:
success = ssh.ChannelReceiveUntilMatch(channelNum,"Password:","ansi",true);
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Display what we've received so far:
Debug.WriteLine(ssh.GetReceivedText(channelNum,"ansi"));

// Send the password. (This is the equivalent of typing at the shell prompt.)
// Again, make sure it uses a bare-LF and not a CRLF.
string password;
password = "myPassword\n";
success = ssh.ChannelSendString(channelNum,password,"ansi");
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Read the response until we get the shell prompt (assuming it's successful)
// In my case, the shell prompt is: "chilkat@vivoMini64:~$ "
string myShellPrompt = "chilkat@vivoMini64:~$";
// It will be different in your case.
success = ssh.ChannelReceiveUntilMatch(channelNum,myShellPrompt,"ansi",true);
if (success != true) {
    // Check the last-error information and the session log...
    Debug.WriteLine(ssh.LastErrorText);
    // Check to see what was received.  
    Debug.WriteLine(ssh.GetReceivedText(channelNum,"ansi"));
    return;
}

// 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, we'll think we're
// already finished...
Debug.WriteLine(ssh.GetReceivedText(channelNum,"ansi"));

// Send a command.  In this case, we are sending the "ls" command:
cmd = "ls\n";
success = ssh.ChannelSendString(channelNum,cmd,"ansi");
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Read until the next command prompt:
success = ssh.ChannelReceiveUntilMatch(channelNum,myShellPrompt,"ansi",true);
if (success != true) {
    // Check the last-error information and the session log...
    Debug.WriteLine(ssh.LastErrorText);
    // Check to see what was received.  
    Debug.WriteLine(ssh.GetReceivedText(channelNum,"ansi"));
    return;
}

// Display the command output:
Debug.WriteLine(ssh.GetReceivedText(channelNum,"ansi"));

// You may continue sending additional commands.
// The technique is: send the command, read until the next command prompt,
// and then fetch/clear the internal receive buffer.

// We're done, so shut it down..

// 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) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Close the channel:
success = ssh.ChannelSendClose(channelNum);
if (success != true) {
    Debug.WriteLine(ssh.LastErrorText);
    return;
}

// Disconnect
ssh.Disconnect();