SSH Remote Shell

See more SSH Examples

Demonstrates starting a shell on a remote SSH server, running a command, and retrieving the output. The example sends the command, signals EOF so the server knows no more input is coming, and then receives the remaining output until the channel closes.

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Ssh;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  ssh: TSsh;
  hostname: string;
  port: Integer;
  password: string;
  channelNum: Integer;
  cmdOutput: string;

begin
  success := False;

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

  //  Demonstrates starting a shell on a remote SSH server, running a command, and retrieving the
  //  output.  No PTY is requested, which is the recommended approach for automation.

  ssh := TSsh.Create;

  hostname := 'ssh.example.com';
  port := 22;
  success := ssh.Connect(hostname,port);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  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.
  password := 'mySshPassword';

  success := ssh.AuthenticatePw('mySshLogin',password);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  channelNum := ssh.OpenSessionChannel();
  if (channelNum < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
  //  raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
  //  echo typed commands back, and skips interactive login scripts.  The output is therefore
  //  clean and easily parseable -- but because no prompt is ever sent, code must not wait for
  //  one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
  success := ssh.SendReqShell(channelNum);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Send the command.  The trailing newline is required -- the shell acts on a line at a time.
  success := ssh.ChannelSendString(channelNum,'ls -l /tmp' + #10,'utf-8');
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Send EOF to tell the server no more input is coming.  The channel stays open and output can
  //  still be received.
  success := ssh.ChannelSendEof(channelNum);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  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;

  //  Receive the remaining output until the server closes the channel.
  success := ssh.ChannelReceiveToClose(channelNum);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  cmdOutput := ssh.GetReceivedText(channelNum,'utf-8');
  if (ssh.LastMethodSuccess = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;
  WriteLn(cmdOutput);

  ssh.Disconnect();


  ssh.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.