这些设置中的大多数是可变的（可以更改的），比如数据库的 URL。而且许多设置可能是敏感的，比如密钥。

因此，通常会将它们提供为由应用程序读取的环境变量。

## 环境变量

!!! tip
    如果您已经知道什么是"环境变量"以及如何使用它们，请随意跳到下面的下一节。

环境变量（也称为"env var"）是一种存在于 Python 代码之外、存在于操作系统中的变量，可以被您的 Python 代码（或其他程序）读取。

您可以在 shell 中创建和使用环境变量，而无需使用 Python：

=== "Linux、macOS、Windows Bash"

    <div class="termy">

    ```console
    // 您可以创建一个名为 MY_NAME 的环境变量
    $ export MY_NAME="Wade Wilson"

    // 然后您可以与其他程序一起使用它，例如

1F240         ; mapped                 ; 3014 672C 3015 #5.2  TORTOISE SHELL BRACKETED CJK UNIFIED IDEOGRAPH-672C
1F241         ; mapped                 ; 3014 4E09 3015 #5.2  TORTOISE SHELL BRACKETED CJK UNIFIED IDEOGRAPH-4E09
1F242         ; mapped                 ; 3014 4E8C 3015 #5.2  TORTOISE SHELL BRACKETED CJK UNIFIED IDEOGRAPH-4E8C
1F243         ; mapped                 ; 3014 5B89 3015 #5.2  TORTOISE SHELL BRACKETED CJK UNIFIED IDEOGRAPH-5B89

- Kubectl now supports shell completion for the <type>/<name> format for specifying resources.
  kubectl now provides shell completion for container names following the `--container/-c` flag of the `exec` command.

- Add fish shell completion to kubectl. ([#92989](https://github.com/kubernetes/kubernetes/pull/92989), [@WLun001](https://github.com/WLun001))

- Upgraded metrics server to `v0.7.0`.
   ([#123504](https://github.com/kubernetes/kubernetes/pull/123504), [@pacoxu](https://github.com/pacoxu))
- `kubeadm completion` error message now displayed supported shell types when an invalid shell was specified.
   ([#122477](https://github.com/kubernetes/kubernetes/pull/122477), [@SataQiu](https://github.com/SataQiu))

- Kubectl shell completions for the bash shell now include descriptions. ([#113636](https://github.com/kubernetes/kubernetes/pull/113636), [@marckhouzam](https://github.com/marckhouzam))

build:rbe_linux_cuda_nvcc --config=rbe_linux_cuda
build:rbe_linux_cuda_nvcc --config=nvcc_clang
build:rbe_linux_cuda_nvcc --repo_env TF_NCCL_USE_STUB=1

build:rbe_win_base --config=rbe_base
build:rbe_win_base --shell_executable=C:\\tools\\msys64\\usr\\bin\\bash.exe
build:rbe_win_base --remote_instance_name=projects/tensorflow-testing/instances/windows
# Don't build the python zip archive in the RBE build.

* Federation can now be deployed using the `federation/deploy/deploy.sh` script. This script does not depend on any of the development environment shell library/scripts. This is an alternative to the current `federation-up.sh`/`federation-down.sh` scripts. Both the scripts are going to co-exist in this release, but the `federation-up.sh`/`federation-down.sh` scripts might be removed in a future release...

- Renamed `apiserver_watch_cache_watch_cache_initializations_total` to `apiserver_watch_cache_initializations_total` ([#109579](https://github.com/kubernetes/kubernetes/pull/109579), [@logicalhan](https://github.com/logicalhan))
- Shell completion is now provided for the "--subresource" flag. ([#109070](https://github.com/kubernetes/kubernetes/pull/109070), [@marckhouzam](https://github.com/marckhouzam))
- Some apiserver metrics were changed, as follows.

  balancer notices that it has been killed. ([#97238](https://github.com/kubernetes/kubernetes/pull/97238), [@andrewsykim](https://github.com/andrewsykim))