The variables are valid only in the specific CMD window, but the %TEMP% directory is used by all instances, of course. Some files from the catalog (wsusscn2.cab) are extracted to %TEMP%, and will be deleted after the script is done with them. So, I'd say: No, it's not safe to run multiple instances.
The only exception would be to run each instance with a different %TEMP% directory. I see two options to achieve this:
- Run each instance as a different Windows user; this can either be on the same system or on another machine like a VM
- Open CMD, set %TEMP% and %TMP% env variables to a different dir, and run wsusoffline\cmd\DownloadUpdates.cmd with the appropriate parameters
However, I'm not sure whether or not the latter will really work because it uses VBS scripts which might get %TEMP% location in a different way (not by env variables).
Regards
Dalai