var LogFileSpec = "D:\\test\\startup.log";
var FS = new ActiveXObject("Scripting.FileSystemObject");
while (!FS.FileExists(LogFileSpec)) WScript.Sleep(1);
var LogFile = FS.OpenTextFile(LogFileSpec, 1 /*ForReading*/);
var line = "";
do {
	while (LogFile.AtEndOfStream) WScript.Sleep(1);
	var char = LogFile.Read(1);
	if (char == '\n') {line = ""; continue;} else line += char;
} while (line != "STARTED_SUCCESSFULLY");
LogFile.Close();
WScript.Echo("Сервер запущен");

option explicit
Dim objFSO, txtFile, x, done
Set objFSO = Createobject("Scripting.FileSystemObject")
Set txtFile = objFSO.OpenTextFile("D:\test\startup.log",1)

Do
Do While Not txtFile.AtEndOfStream
  x=txtFile.Readline
  If InStr(x, "STARTED_SUCCESSFULLY") Then
      MsgBox "Сервер запущен"
	  done = true
      Exit Do
  End If  
 Loop
Loop