I realised today that despite having installed a modern version of Bash (via brew install bash), I was still running Bash v3.2.57—the system version of MacOS—as my default login shell.

$ bash --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin21)
Copyright (C) 2007 Free Software Foundation, Inc.

This is because there are some post-installation steps that need to be followed, and these aren’t mentioned in the Homebrew formulae notes.

Specifically you need to allow-list the Homebrew-installed version so it can be used as a login shell by adding the path to /etc/shells:

echo $(brew --prefix)/bin/bash | sudo tee -a /etc/shells

Then configure MacOS to use the Homebrew Bash as your user’s default login shell:

chsh -s $(brew --prefix)/bin/bash

It’s also possible to change a user’s default login shell from the “Users and Groups” section of system preferences. To do this, CTRL-click on your user and use the “advanced options” pop-up.

Verify this has worked by starting a new shell session and running:

echo $BASH_VERSION
5.2.12(1)-release

Autocomplete woes

This was a yak-shave TIL shaken out of debugging why Git autocomplete wasn’t working. As part of the investigation, I realised the bash-completion@2 Homebrew package script wasn’t sourcing each package’s autocomplete files as the Bash version test wasn’t passing.

As it turns out, upgrading Bash and getting bash-completion@2 to work didn’t fix the Git issue as the root cause was a incompatibility between hub and modern Git versions.