bash auto-completion on macOS [page]deterministic

### Introduction

The kubectl completion script for Bash can be generated with `kubectl completion bash`. Sourcing this script in your shell enables kubectl completion.

However, the kubectl completion script depends on [bash-completion](https://github.com/scop/bash-completion) which you thus have to previously install.

> Warning: There are two versions of bash-completion, v1 and v2. V1 is for Bash 3.2 (which is the default on macOS), and v2 is for Bash 4.1+. The kubectl completion script doesn't work correctly with bash-completion v1 and Bash 3.2. It requires bash-completion v2 and Bash 4.1+. Thus, to be able to correctly use kubectl completion on macOS, you have to install and use Bash 4.1+ ([*instructions*](https://apple.stackexchange.com/a/292760)). The following instructions assume that you use Bash 4.1+ (that is, any Bash version of 4.1 or newer).

### Upgrade Bash

The instructions here assume you use Bash 4.1+. You can check your Bash's version by running:

```bash echo $BASH_VERSION ```

If it is too old, you can install/upgrade it using Homebrew:

```bash brew install bash ```

Reload your shell and verify that the desired version is being used:

```bash echo $BASH_VERSION $SHELL ```

Homebrew usually installs it at `/usr/local/bin/bash`.

### Install bash-completion

> Note: As mentioned, these instructions assume you use Bash 4.1+, which means you will install bash-completion v2 (in contrast to Bash 3.2 and bash-completion v1, in which case kubectl completion won't work).

You can test if you have bash-completion v2 already installed with `type _init_completion`. If not, you can install it with Homebrew:

```bash brew install bash-completion@2 ```

As stated in the output of this command, add the following to your `~/.bash_profile` file:

```bash brew_etc="$(brew --prefix)/etc" && [[ -r "${brew_etc}/profile.d/bash_completion.sh" ]] && . "${brew_etc}/profile.d/bash_completion.sh" ```

Reload your shell and verify that bash-completion v2 is correctly installed with `type _init_completion`.

### Enable kubectl autocompletion

You now have to ensure that the kubectl completion script gets sourced in all your shell sessions. There are multiple ways to achieve this:

• Source the completion script in your `~/.bash_profile` file:

```bash echo 'source <(kubectl completion bash)' >>~/.bash_profile ```

• Add the completion script to the `/usr/local/etc/bash_completion.d` directory:

```bash kubectl completion bash >/usr/local/etc/bash_completion.d/kubectl ```

• If you have an alias for kubectl, you can extend shell completion to work with that alias:

```bash echo 'alias k=kubectl' >>~/.bash_profile echo 'complete -o default -F __start_kubectl k' >>~/.bash_profile ```

• If you installed kubectl with Homebrew (as explained [here](/docs/tasks/tools/install-kubectl-macos/#install-with-homebrew-on-macos)), then the kubectl completion script should already be in `/usr/local/etc/bash_completion.d/kubectl`. In that case, you don't need to do anything.

> Note: The Homebrew installation of bash-completion v2 sources all the files in the `BASH_COMPLETION_COMPAT_DIR` directory, that's why the latter two methods work.

In any case, after reloading your shell, kubectl completion should be working.