Lazarus Pascal

Check Whether SSH Channel EOF Was Received

Demonstrates the Chilkat Ssh.ChannelReceivedEof method, which reports whether an SSH EOF message has been received for a channel. The only argument is the channel number. EOF means the server will send no more ordinary channel data, but it does not close the channel.

Background: EOF and CLOSE are separate events, and the distinction matters when deciding whether a command has truly finished. A server commonly sends EOF first and CLOSE afterward; in that interval this method is true while ChannelReceivedClose is still false, and the channel remains open and counted. EOF is the signal that all output has been produced — useful when you want to stop reading without waiting for the full close handshake. It returns false for an invalid, released, or locally closed channel.

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Lazarus Pascal

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;
  sshPort: Integer;
  password: string;
  channelNum: Integer;

begin
  success := False;

  //  Demonstrates the Ssh.ChannelReceivedEof method, which reports whether an SSH EOF message has
  //  been received for a channel.  The only argument is the channel number.  EOF means the server
  //  will send no more ordinary channel data, but it does not close the channel.

  ssh := TSsh.Create;

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

  success := ssh.SendReqExec(channelNum,'ls -l /tmp');
  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;

  success := ssh.ChannelReceiveToClose(channelNum);
  if (success = False) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  if (ssh.ChannelReceivedEof(channelNum)) then
    begin
      WriteLn('EOF was received -- no more ordinary channel data will arrive.');
    end
  else
    begin
      WriteLn('No EOF has been received.');
    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.