Detecting a program if it is running.

function IsFileInUse(path: String): Boolean;
var
  f: file;
  r: integer;
begin
  r := - 1;
  system.AssignFile(f, path);
  {$I-}
  reset(f);
  {$I+}
  r := ioresult;  {sm(ns(r));}
  {5 = access denied}
  if (r = 32) or (r = 5) then
    result := true
  else
    result := false;
  if r = 0 then
    system.close(f);
end;

//Usage:
procedure TForm1.Button1Click(Sender: TObject);
begin
 if IsFileInUse('C:\file.exe') then ShowMessage('Program is in use');
end;