The procedures detailed below can be used to update the CoreCLR runtime and JIT that are part of the .NET Core shared runtime and libraries, also known as Microsoft.NETCore.App in-place. This will enable portable applications to take advantage of updates to the shared files. The preferred way to update Microsoft.NETCore.App is to install the new version side-by-side but there may be times when an updated NETCore.App is not yet available while the required components have been released as NuGet packages.
If your system doesn't recognize *nupkg files as archives, rename them to *.zip or *.tar.gz and extract the `/runtimes` directory to a temporary location. For CoreCLR there will be `/native` and `/lib/netstandard1.0` directories under `/runtimes`. JIT will have only a `/native` directory. Here's an example of what the tmp location should look like when you are done if the Debian 8 packages were used. The list of binaries will be different for other distros.
Since we'll be updating files in-place it's a good idea to make a backup. First you need to locate the `Microsoft.NETCoreApp/1.0.0` directory. If you used the installers for Ubuntu, 1.0.0 will be found under `/usr/share/dotnet/shared/Microsoft.NETCore.App/`. Other distro installations are still manual extraction from archives so it's whereever you copied the directory structure. Something like `/opt/dotnet/shared/Microsoft.NETCore.App` would not be uncommon.
Now that `Microsoft.NETCore.App/1.0.0` has been located, the easiest way to make the backup will be to copy the entire directory which will be updated. `sudo rsync -r 1.0.0/ 1.0.0-backup/` will create the backup directory and copy the entire contents of the source directory.
If the backup was successful `diff 1.0.0/ 1.0.0-backup` will return nothing.
## Copy new files to the shared directory ##
The final step is to update the files in `Microsoft.NETCore.App/1.0.0` by copying the files from the temporary location into Microsoft.NETCoreApp/1.0.0. Do not copy the /native or /lib directories, just the files.
At this point, any portable application on the system will make use of the updated runtime files which you have copied into the `Microsoft.NETCoreApp/1.0.0` directory.