Execute an external program from inside a Delphi application

Maybe are several ways to do this but I dont know how good are these approaches:

1. Check if a process is active (there must be an API for this)
2. Maybe your external application can do something you can notice from your delphi program. For instance, if a file open was closed. So you can try to open that file. If you get an error, you probably are not done with the external app running. I dont know how good is this specific approach.
3. I was thinking in measure how much time the external app runs. So you can put a timer to expecting that app finished and you resume your delphi program.

I found this code, maybe it can work for you:

// Execute the Windows Calculator and pop up
// a message when the Calc is terminated.
uses ShellApi;
...
var
  SEInfo: TShellExecuteInfo;
  ExitCode: DWORD;
  ExecuteFile, ParamString, StartInString: string;
begin
  ExecuteFile:='c:\Windows\Calc.exe';
 
  FillChar(SEInfo, SizeOf(SEInfo), 0);
  SEInfo.cbSize := SizeOf(TShellExecuteInfo);
  with SEInfo do begin
    fMask := SEE_MASK_NOCLOSEPROCESS;
    Wnd := Application.Handle;
    lpFile := PChar(ExecuteFile);
{
ParamString can contain the
application parameters.
}
// lpParameters := PChar(ParamString);
{
StartInString specifies the
name of the working directory.
If ommited, the current directory is used.
}
//  lpDirectory := PChar(StartInString);
    nShow := SW_SHOWNORMAL;
  end;
  if ShellExecuteEx(@SEInfo) then begin
    repeat
      Application.ProcessMessages;
      GetExitCodeProcess(SEInfo.hProcess, ExitCode);
    until (ExitCode <> STILL_ACTIVE) or
       Application.Terminated;
    ShowMessage('Calculator terminated');
  end
  else ShowMessage('Error starting Calc!');
end;

Also, I found this

An example uses "CreateProcress" (which is more appropriate on a 32bit-platform)  to start notepad and waits until you close it:


var
    StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
    NotepadExe:  String;
begin
    SetLength(NotepadExe, MAX_PATH);
    GetWindowsDirectory(Pchar(NotepadExe), MAX_PATH);
    StrCat(Pchar(NotepadExe),'\notepad.exe');

    ZeroMemory(@StartupInfo,SizeOf(TStartupInfo));
    StartupInfo.cb := SizeOf(TStartupInfo);

    if(CreateProcess(Pchar(NotepadExe), Nil, Nil, Nil,
                     False, NORMAL_PRIORITY_CLASS,
                     Nil, Nil, StartupInfo,ProcessInfo))    
    then
    begin
        WaitForSingleObject(pi.hProcess,INFINITE);
        ShowMessage('Hi there');
        CloseHandle(ProcessInfo.hProcess);
        CloseHandle(ProcessInfo.hThread);
    end
end;

Note: none of these ideas are mine. I found on the net: https://www.tek-tips.com/viewthread.cfm?qid=186953

Will try some of these codes and come back to experts once completed...

How can I pass a parameter in the two first example of the notepad ?
I need to pass a file name...

I tried RunAsAdminAndWait passing the notepad exe full file name
I got the Windows warning that I was running as admin, I accepted, then nothing else, no notepad running and back to the caller

To pass a filename to a notepad, you can try this:

begin
  ShellExecute(Handle,'open',
  'c:\windows\notepad.exe',
  'c:\SomeText.txt', nil, SW_SHOWNORMAL) ;
end;

Remember to include shellapi in your uses clause.

I tried RunAsAdminAndWait passing the notepad exe full file name
I got the Windows warning that I was running as admin, I accepted, then nothing else, no notepad running and back to the caller

Ok, here's a simple sample using my function tested on Delphi 10.4

unit unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Winapi.Shellapi, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function RunAsAdminAndWait(hWnd: hWnd; FileName: string; Parameters: string;
  ShowCommand: Integer = SW_SHOWNORMAL): Boolean;
{
  Redesign for UAC Compatibility (UAC)
  http://msdn.microsoft.com/en-us/library/bb756922.aspx
}
var
  sei: TShellExecuteInfo;
  ExitCode: dword;
begin
  ZeroMemory(@sei, SizeOf(sei));
  sei.cbSize := SizeOf(TShellExecuteInfo);
  sei.Wnd := hWnd;
  sei.fMask := SEE_MASK_FLAG_DDEWAIT or SEE_MASK_FLAG_NO_UI or
    SEE_MASK_NOCLOSEPROCESS;
  sei.lpVerb := pchar('runas');
  sei.lpFile := pchar(FileName); // PAnsiChar;
  if Parameters <> '' then
    sei.lpParameters := pchar(Parameters); // PAnsiChar;
  sei.nShow := ShowCommand; // Integer;
  if ShellExecuteEx(@sei) then
  begin
    repeat
      Application.ProcessMessages;
      GetExitCodeProcess(sei.hProcess, ExitCode);
    until (ExitCode <> STILL_ACTIVE) or Application.Terminated;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  RunAsAdminAndWait(Application.handle, 'c:\windows\notepad.exe', 'c:\Test.txt',
    SW_SHOWNORMAL);
  showMessage('Notepad closed');
end;

end.

Select allOpen in new window

Depending on the idle time your want to give other applications and the responsiveness of your UI, the actual wait should be:

  bOK := Boolean(ShellExecuteEx(@Info));
  if bOK then
  begin
    if bWait then
    begin
      while
        WaitForSingleObject(Info.hProcess, 100) = WAIT_TIMEOUT
        do Application.ProcessMessages;
      bOK := GetExitCodeProcess(Info.hProcess, DWORD(Result));
    end
    else
      Result := 0;
  end;

Select allOpen in new window

where WAIT_TIMEOUT is a value between 500ms, especially for animating or updating the wait message and the average external application runtime.

btw, for optimal responsiveness, you would use a thread to run the execute in and then you can do in the UI what you want.