The Software Update issue used to be
* that once the Installer was downloaded
and allowed to run, it would be auto deleted. The trick, then. was to stop the installation after the download, copy the installer to another location, and finish the installation. So if you proceeded with the installation, you may have lost part of all of the installer. Even so, you might want to check /Library/Updates to see what’s left there.
A better way is to download from
Apple Support - Downloads, although items may appear there later then in Software Update. To me that’s not a problem, as I’d rather wait a few days to see how an update plays out, in case there are problems. And while you now can squirrel away your Installers (they will appear in the folder you’ve designated for browser downloads), note that they
still leave an ‘impression’ on /Library/Updates.
Finally, I’d recommend to download Combo Updaters when available. These contain all relevant content from previous updaters of your version of Mac OS X, and running them can repair certain problems that otherwise might require re-installation of the OS.
*) I’m not sure that’s still the case, and unfortunately the various versions of Mac OS X haven’t been all that consistent in this respect.
