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Although Windows NT Magazine and others have covered the Windows NT Server 4.0 Resource Kit utility Sysdiff, the coverage has typically focused on the utility's large tasks, such as building application install files and conducting unattended software installs. Support personnel who work with NT might find my use for Sysdiff valuable and suitable for daily use. Sysdiff's functionality is relatively simple. You run Sysdiff with the /snap switch to take a system snapshot, recording all file and Registry settings. You install the required software or make system changes, then run Sysdiff with the /diff switch. The software compares any new files or Registry changes and packages these changes into an install file. If you want to add this package file to another workstation (provided you have configured it similarly), you run Sysdiff with the /apply switch.
One big mystery about installing a new application or making system changes is what changes you're actually making on your system—something you're especially interested in when something goes wrong. Wouldn't it be nice to have a list of all the system changes you make during a software or an ISP configuration install? Fortunately, Sysdiff has a /dump switch that saves a list of all file and Registry changes to a text file. If you’re big on manually hacking the NT Registry, you’ll find this tool invaluable for determining proper Registry settings before making manual changes. For example, my company had several NT clients with incorrect time-zone settings. Instead of visiting each workstation and changing the settings manually, we decided to push the time-zone Registry changes remotely from a batch file. However, we didn’t know what the Registry settings were, and searching the Registry manually is not the most accurate option. Sysdiff made this easy. We simply set a workstation to the incorrect time zone, took the snapshot, corrected the time zone, and then took the diff reading. We then used the /dump switch to dump the Registry changes to a text file and noted these changes in our batch file. We have also used Sysdiff for troubleshooting when an install was copying incompatible ODBC DLLs to a system.
Although no documentation states this, but sure that you have a sysdiff.inf file in the same folder as Sysdiff. The sysdiff.inf text file tells Sysdiff which files, folders, and Registry areas to exclude during operation. For example, if you're making only Registry changes, you can save time by editing sysdiff.inf to tell Sysdiff to skip the C: drive.
The time this utility has saved us in troubleshooting and system-configuration change has been immeasurable. By the way, we also use Sysdiff to build and distribute software to clients.
—Marty Scher
mscher@fleetcc.com