If you encounter the bash error message: _init_completion: command not found when trying to use bash-completion (and you are on macOS), the error is most likely due to having an older version of bash installed such as 3.2 (which is the default on macOS).

The easiest way to solve this is of course to upgrade using brew. At the time of this writing this will install 5.1.8(1)-release, but all we really need is v4.1+ in order to make use of bash-completion v2 which includes _init_completion.

Here’s a great article by the k8s folks that explains the process step-by-step.

But if for some reason we wanted to keep using the default bash shell on macOS along with bash-completion v1, we could steal a hack found in the kubctl completion script:

# Homebrew on Macs have version 1.3 of bash-completion which doesn't include
# _init_completion. This is a very minimal version of that function.
__kubectl_init_completion()
{