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".

Download Chilkat SSH / SFTP ActiveX

uses
    Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
    Dialogs, StdCtrls,
    CHILKATRSALib_TLB,
    CHILKATSSHLib_TLB,
    OleCtrls;

...

procedure TForm1.Button1Click(Sender: TObject);
var
ssh: TChilkatSsh;
success: Integer;
hostname: String;
port: Integer;
channelNum: Integer;
termType: String;
widthInChars: Integer;
heightInChars: Integer;
pixWidth: Integer;
pixHeight: Integer;
cmd: String;
password: String;

begin
//  Important: It is helpful to send the contents of the
//  ssh.LastErrorText property when requesting support.

ssh := TChilkatSsh.Create(Self);

//  Any string automatically begins a fully-functional 30-day trial.
success := ssh.UnlockComponent('30-day trial');
if (success <> 1) then
  begin
    ShowMessage(ssh.LastErrorText);
    Exit;
  end;

//  Hostname may be an IP address or hostname:
hostname := '192.168.1.117';
port := 22;

//  Keep a session log, which is available via the SessionLog
//  property:
ssh.KeepSessionLog := 1;

success := ssh.Connect(hostname,port);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  When reading, if no additional data arrives for more than
//  5 seconds, then abort:
ssh.IdleTimeoutMs := 5000;

//  SSH Server Authentication
//  If there is no login/password required, you must still call
//  AuthenticatePw and use any values for login/password.
success := ssh.AuthenticatePw('chilkat','myPassword');
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Open a session channel.

channelNum := ssh.OpenSessionChannel();
if (channelNum < 0) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Request a pseudo-terminal
termType := 'dumb';
widthInChars := 120;
heightInChars := 40;
pixWidth := 0;
pixHeight := 0;
success := ssh.SendReqPty(channelNum,termType,widthInChars,heightInChars,pixWidth,pixHeight);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Start a shell on the channel:
success := ssh.SendReqShell(channelNum);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  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.)

cmd := 'su' + #10;
success := ssh.ChannelSendString(channelNum,cmd,'ansi');
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Read until we get the prompt for the password:
success := ssh.ChannelReceiveUntilMatch(channelNum,'Password:','ansi',1);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Display what we've received so far:
Memo1.Lines.Add(ssh.GetReceivedText(channelNum,'ansi'));

//  Send the password.
//  Again, make sure it uses a bare-LF and not a CRLF.

password := 'myPassword' + #10;
success := ssh.ChannelSendString(channelNum,password,'ansi');
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Read the response until we get the shell prompt (assuming it's successful)
//  In my case, the shell prompt is: "root@ubuntu:/home/chilkat# "
//  It will be different in your case.
success := ssh.ChannelReceiveUntilMatch(channelNum,'root@ubuntu:/home/chilkat#','ansi',1);
if (success <> 1) then
  begin
    //  Check the last-error information and the session log...
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    //  Check to see what was received.
    Memo1.Lines.Add(ssh.GetReceivedText(channelNum,'ansi'));
    Exit;
  end;

//  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...
Memo1.Lines.Add(ssh.GetReceivedText(channelNum,'ansi'));

//  Send a command.  In this case, we are sending the "ls" command:
cmd := 'ls' + #10;
success := ssh.ChannelSendString(channelNum,cmd,'ansi');
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Read until the next command prompt:
success := ssh.ChannelReceiveUntilMatch(channelNum,'root@ubuntu:/home/chilkat#','ansi',1);
if (success <> 1) then
  begin
    //  Check the last-error information and the session log...
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    //  Check to see what was received.
    Memo1.Lines.Add(ssh.GetReceivedText(channelNum,'ansi'));
    Exit;
  end;

//  Display the command output:
Memo1.Lines.Add(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 <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Close the channel:
success := ssh.ChannelSendClose(channelNum);
if (success <> 1) then
  begin
    Memo1.Lines.Add(ssh.LastErrorText);
    Memo1.Lines.Add(ssh.SessionLog);
    Exit;
  end;

//  Disconnect
ssh.Disconnect();
end;