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Before downloading the updates from the result list, WuInstall checks in the cache_dir if the update has already been downloaded there by another machine. If the update is not the cache folder, WuInstall downloads the update (from the configured download location - WSUS and/or windowsupdate.com) and puts it into the cache directory, in a subfolder which has the same name as the Update ID.
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/nocachedel
In combination with /install_cache or /download_cache: does not clear the cache directory on error.
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