SSH Parallel Remote Commands on a Single Server

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Demonstrates running several commands in parallel on one SSH server and collecting each command's output as it finishes. QuickCmdSend starts each command and returns immediately; QuickCmdCheck reports them as they complete.

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;
  port: Integer;
  password: string;
  channel1: Integer;
  channel2: Integer;
  channel3: Integer;
  pollTimeoutMs: Integer;
  numFinished: Integer;
  channel: 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 running several commands in parallel on a single SSH server and collecting each
  //  command's output as it finishes.

  ssh := TSsh.Create;

  port := 22;
  success := ssh.Connect('ssh.example.com',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;

  //  QuickCmdSend starts a command and returns immediately, so all three run concurrently, each on
  //  its own session channel.
  channel1 := ssh.QuickCmdSend('df');
  if (channel1 < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  channel2 := ssh.QuickCmdSend('date');
  if (channel2 < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  channel3 := ssh.QuickCmdSend('echo hello world');
  if (channel3 < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Collect the results.  QuickCmdCheck returns the channel number of a completed command,
  //  -1 when commands are still pending but none finished within the timeout, or -2 when nothing
  //  remains to be checked (or an error occurred).
  pollTimeoutMs := 50;
  numFinished := 0;
  while numFinished < 3 do
    begin
      channel := ssh.QuickCmdCheck(pollTimeoutMs);
      if (channel = -2) then
        begin
          WriteLn(ssh.LastErrorText);
          Exit;
        end;

      if (channel >= 0) then
        begin
          WriteLn('---- channel ' + channel + ' finished ----');
          cmdOutput := ssh.GetReceivedText(channel,'utf-8');
          if (ssh.LastMethodSuccess = False) then
            begin
              WriteLn(ssh.LastErrorText);
              Exit;
            end;
          WriteLn(cmdOutput);
          numFinished := numFinished + 1;
        end;
    end;

  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.