date vs gdate

So I remember in the future: by default, MacOS/OS X's date is the BSD version, not the GNU one. Which doesn't let you do things like date --rfc-3339 date -d tomorrow to get the RFC-3339 (ie Best Date Format) formatted string for tomorrow (2019-12-19 as of this writing).

To fix that:

brew install coreutils

Then in .bashrc:

alias date='gdate'

I actually put that in .bashrc.local, as I sync my .bashrc with git. To allow me to do computer-specific things, near the top of my .bashrc I have

# Source things I don't want to put on github
if [ -f ~/.bashrc.local ]; then
	source ~/.bashrc.local
fi

I'd recommend doing that with .vimrc as well! (and putting your plugin definitions in a separate file to keep your .vimrc clean, with a local-only plugin file conditionally included as well)