Installing this is easy:
* Download ZIP archive and unpack
'sudo mv path-to-butler-folder /usr/local' cd /usr/local/bin 'sudo ln -s butler /usr/local/name-of-butler-folder-you-moved'
If you're on modern macOS with zsh as your default Terminal shell, be sure to set your Itch API key in EITHER of these ways:
* Edit ~/.zshrc (~/.bashrc on older releases that use bash as the default Terminal shell) and enter the following:
export BUTLER_API_KEY="key-you-generated-on-itch"
Save your .zshrc or .bashrc file and then in your Terminal window execute the command below. Use the filename associated with your Terminal shell.
'source ~/.zshrc' or 'source ~/.bashrc'
OR save your key in the file
~/Library/Application Support/itch/butler_creds
All this done, you should be able to 'butler --version' and get the version of your installed butler. If successful, 'butler login' is next ...