Update directions for macOS bash completion

docs/tasks/tools/install-kubectl.md

@@ -7,14 +7,14 @@ redirect_from:
 - "/docs/tasks/kubectl/install/"
 - "/docs/tasks/kubectl/install.html"
 - "/docs/user-guide/prereqs/"
-- "/docs/user-guide/prereqs.html" 
+- "/docs/user-guide/prereqs.html"
 ---
 {% capture overview %}
 Use the Kubernetes command-line tool, [kubectl](/docs/user-guide/kubectl), to deploy and manage applications on Kubernetes. Using kubectl, you can inspect cluster resources; create, delete, and update components; and look at your new cluster and bring up example apps.
 {% endcapture %}
 
 {% capture prerequisites %}
-Use a version of kubectl that is the same version as your server or later. Using an older kubectl with a newer server might produce validation errors. 
+Use a version of kubectl that is the same version as your server or later. Using an older kubectl with a newer server might produce validation errors.
 {% endcapture %}
 
 Here are a few methods to install kubectl.
@@ -26,7 +26,7 @@ Here are a few methods to install kubectl.
 
         curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/darwin/amd64/kubectl
 
-    To download a specific version, replace the `$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)` portion of the command with the specific version. 
+    To download a specific version, replace the `$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)` portion of the command with the specific version.
 
     For example, to download version {{page.fullversion}} on MacOS, type:
 
@@ -38,7 +38,7 @@ Here are a few methods to install kubectl.
     chmod +x ./kubectl
     ```
 
-3. Move the binary in to your PATH. 
+3. Move the binary in to your PATH.
 
     ```
     sudo mv ./kubectl /usr/local/bin/kubectl
@@ -50,9 +50,9 @@ Here are a few methods to install kubectl.
 
         curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
 
-    To download a specific version, replace the `$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)` portion of the command with the specific version. 
+    To download a specific version, replace the `$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)` portion of the command with the specific version.
 
-    For example, to download version {{page.fullversion}} on Linux, type: 
+    For example, to download version {{page.fullversion}} on Linux, type:
 
         curl -LO https://storage.googleapis.com/kubernetes-release/release/{{page.fullversion}}/bin/linux/amd64/kubectl
 
@@ -62,7 +62,7 @@ Here are a few methods to install kubectl.
     chmod +x ./kubectl
     ```
 
-3. Move the binary in to your PATH. 
+3. Move the binary in to your PATH.
 
     ```
     sudo mv ./kubectl /usr/local/bin/kubectl
@@ -97,7 +97,7 @@ kubectl can be installed as part of the Google Cloud SDK.
 gcloud components install kubectl
 ```
   3. Run `kubectl version` to verify that the verison you've installed is sufficiently up-to-date.
-  
+
 ## Install with Homebrew on macOS
 
   1. If you are on macOS and using [Homebrew](https://brew.sh/) package manager, you can install with:
@@ -117,7 +117,7 @@ Check that kubectl is properly configured by getting the cluster state:
 ```shell
 $ kubectl cluster-info
 ```
-If you see a URL response, kubectl is correctly configured to access your cluster. 
+If you see a URL response, kubectl is correctly configured to access your cluster.
 
 If you see a message similar to the following, kubectl is not correctly configured:
 ```shell
@@ -142,28 +142,29 @@ echo "source <(kubectl completion bash)" >> ~/.bashrc
 ```
 
 ### On macOS, using bash
-On macOS, autocompletion works if you install using `brew install kubectl`,
+On macOS, you will need to install bash-completion support via [Homebrew](https://brew.sh/) first:
-and not if you downloaded kubectl directly.
-
-Install the bash-completion support:
 
 ```shell
+## If running Bash 3.2 included with macOS
 brew install bash-completion
+## or, if running Bash 4.1+
+bash install bash-completion@2
 ```
 
-To add kubectl autocompletion to your current shell, run:
+Follow the "caveats" section of brew's output to add the appropriate bash completion path to your local .bashrc.
 
-```shell
+If you've installed kubectl using the [Homebrew instructions](#install-with-homebrew-on-macos) then kubectl completion should start working immediately.
-source $(brew --prefix)/etc/bash_completion
+
-source <(kubectl completion bash)
+If you have installed kubectl manually, then run: `source <(kubectl completion bash)`
-```
 
 To add kubectl autocompletion to your profile (so it is automatically loaded in future shells):
 
 ```shell
-echo "source $(brew --prefix)/etc/bash_completion" >> ~/.bash_profile
 echo "source <(kubectl completion bash)" >> ~/.bash_profile
 ```
+
+The Homebrew project is independent from kubernetes, so the bash-completion packages are not guaranteed to work.
+
 {% endcapture %}
 {% capture whatsnext %}
 [Learn how to launch and expose your application.](/docs/user-guide/quick-start)