Pascal (Lazarus/Delphi)

Using sudo in an SSH Shell Session

See more SSH Examples

Demonstrates how to run a command as sudo in a shell session. Pascal (Lazarus/Delphi)

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,
  Chilkat.StringBuilder;

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

procedure RunDemo;
var
  success: Boolean;
  ssh: TSsh;
  port: Integer;
  channelNum: Integer;
  sbCommands: TStringBuilder;

begin
  success := False;

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

  ssh := TSsh.Create;

  port := 22;
  success := ssh.Connect('the-ssh-server.com',port);
  if (success <> True) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Authenticate using login/password:
  success := ssh.AuthenticatePw('theSshLogin','theSshPassword');
  if (success <> True) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Start a shell session.
  //  (The QuickShell method was added in Chilkat v9.5.0.65)
  channelNum := ssh.QuickShell();
  if (channelNum < 0) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Construct a StringBuilder with our command ("ls") run with "sudo"
  //  Note: The line-endings are potentially important.  Some SSH servers may
  //  require either LF or CRLF line endings.  (Unix/Linux/OSX servers typically
  //  use bare-LF line endings.  Windows servers likely use CRLF line endings.)

  //  Using "sudo -S" causes the sudo prompt to be written to stderr,
  //  and the password is read from stdin (i.e. from the echo command ouput).
  //  The sudo commands -p option allows us to set the prompt, and we can set it to
  //  the empty string, thus eliminating the prompt from the stderr completely.
  //  This allows us to run the command as root (super-user) with no prompt.
  sbCommands := TStringBuilder.Create;
  sbCommands.Append('echo "theSshPassword" | sudo -S -p "" ls' + #10);

  //  Add another command to echo a marker string that
  //  we'll use in ChannelReceiveUntilMatch below.
  //  The use of single quotes around 'IS' is a trick so that the output
  //  of the command is "THIS IS THE END OF THE SCRIPT", but the terminal echo
  //  includes the single quotes.  This allows us to read until we see the actual
  //  output of the last command.
  sbCommands.Append('echo THIS ''IS'' THE END OF THE SCRIPT' + #10);

  //  Send the commands..
  success := ssh.ChannelSendString(channelNum,sbCommands.GetAsString(),'ansi');
  if (success <> True) then
    begin
      WriteLn(ssh.LastErrorText);
      Exit;
    end;

  //  Send an EOF to indicate no more commands will be sent.
  //  For brevity, we're not checking the return values of each method call.
  //  Your code should check the success/failure of each call.
  success := ssh.ChannelSendEof(channelNum);

  //  Receive output up to our marker.
  success := ssh.ChannelReceiveUntilMatch(channelNum,'THIS IS THE END OF THE SCRIPT','ansi',True);

  //  Close the channel.
  //  It is important to close the channel only after receiving the desired output.
  success := ssh.ChannelSendClose(channelNum);

  //  Get any remaining output..
  success := ssh.ChannelReceiveToClose(channelNum);

  //  Get the complete output for all the commands in the session.
  WriteLn('--- output ----');
  WriteLn(ssh.GetReceivedText(channelNum,'ansi'));


  ssh.Free;
  sbCommands.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.