When the Unity Package Manager downloads package contents and metadata from a registry, it stores them in a global cache. This makes reusing and sharing packages more efficient, and allows you to install and update stored packages even when offline.
Note: The global cache doesn’t include packages in the
.unitypackage format that come the Asset Store. The Package Manager stores these types of packages in a separate cache. For more information, see Asset Store packages.
默认情况下，Unity 将全局缓存存储在根目录中，根目录取决于操作系统（在 Windows 上还取决于用户帐户类型）：
Tip: You can override the location of this root directory. See Customizing the shared cache locations for more information.
The Package Manager global cache uses two different subsidiary caches, each serving a different purpose. The Package Manager stores these subsidiary caches in subdirectories under the folder of the global cache:
||存储使用 npm 协议从注册表获得的数据。这包括包元数据和包 tarball。|
||此缓存包含从注册表获取的包 tarball 的未压缩内容。|
Inside each of these subfolders, each registry has its own path so that packages hosted on different registries aren’t mixed up.
Tip: You can override the location of these folders. See Customizing the shared cache locations for more information.
The user account running the Unity Editor process must have full write permissions on the root directory and its contents. Without these permissions, the Package Manager can’t download and save the package metadata and contents in the cache.