*****************************************************************
* Neveprise Inc. Delphi FAQ					*
*****************************************************************
* Section: Misc			Topic:   Exec app and wait	*
* Created: July 27th, 1999	Revised: July 27th, 1999 	*
* Updates: www.neveprise.de	Info:	 support@neveprise.de	*
*****************************************************************

Q: How can I execute an external application and let my one wait
	until it is finished / detect finalization?

A: Often this function is described as "ExecAndWait". Using the
	CreateProcess() function you can archieve this. This function
	creates a process (an app is a process having one or more
	threads), passing the process handle to an other function
	that queries its existence, we can reach our goal:


function ExecAndWaitH(Filename, Parameter: string; nCmdShow: integer): longword;
var zAppName:    array[0..max_path] of char;
    zParameter:  array[0..max_path] of char;
    zCurDir: 	 array[0..max_path] of char;
    WorkDir: 	 string;
    StartupInfo: TStartupInfo;
    ProcessInfo: TProcessInformation;
begin
StrPCopy(zAppName, FileName);
StrPCopy(zParameter, Parameter);
GetDir(0, WorkDir);
StrPCopy(zCurDir, WorkDir);
FillChar(StartupInfo, Sizeof(StartupInfo),#0); //init, remove trash
StartupInfo.cb:=Sizeof(StartupInfo);
StartupInfo.dwFlags:=StartF_UseShowWindow; //we want to set window flags
StartupInfo.wShowWindow:=nCmdShow; //that is it (e.g. ws_ShowNormal)
if not CreateProcess(zAppName, zParameter, nil, nil, false,
	             Create_New_Console or Normal_Priority_Class, nil, nil,
		     StartupInfo, ProcessInfo) then Result:=0
else begin
   WaitForSingleObject(ProcessInfo.hProcess, Infinite);
   GetExitCodeProcess(ProcessInfo.hProcess, Result);
end;
end;


WaitForSingleobject() retrieves the Process' handle and only continues
code's flow if the process has terminated, while GetExitCodeProcess()
returns eventual error, 0 means all okay.
To look up other parameters used un StartupInfo.wShowWindow please refer
the Win32 SDK help delivered with Delphi. The flags are listed under the
function ShowWindow().
A second thing of interest is the sixth parameter of CreateProcess():
there you can specify the priority of the application to be started. That
means that you can "give" apps more computing cycles, but that should
only be done if really nessessary (e.g. special timers etc.). To get the
other params for these priority classes, refer CreateProcess() in the
Win32 help.

	Blazko