Commands

Diff two directories

diff --brief --recursive -x '.git' -x 'autoload' ~/.config/nvim ~/local.usersnap.com/.config/nvim

Find and replace recursively in a directory

find docs -name '*.md' | xargs sed -i "" 's/\[/\[:fontawesome-solid-link: /g'

Source.

Note: -i "" is only for MacOS. More here.