Using the file
class.ext_update.php is discouraged.
Use the new API as explained in this chapter.
While the update wizards already provide a skeleton and integration into TYPO3
CMS, there is a file from old times. This file is placed in the extension root
If this file is found it will install a new menu item, "UPDATE", in the
Extension Manager when looking at details for the extension. When this menu item
is selected the class inside of this file (named
ext_update) will be
instantiated and the method
main() will be called and expected to return
Also the method
access() has to be added. This method should return a
boolean value whether or not the menu item should be shown. This feature is
meant to disable the update tool if it has already been run and doesn't need to