This might come in handy when writing BDD tests. The simple bash below extracts lines with RFC Key Words from a document.

curl -s https://raw.githubusercontent.com/adlnet/xAPI-Spec/1.0.3/xAPI.md | grep -nwE --color=auto MUST

List of the defined keywords: “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL”

Save extract to file:

curl -s https://raw.githubusercontent.com/adlnet/xAPI-Spec/1.0.3/xAPI.md | grep -nwE --color=auto MUST > MUST-1.0.3-xAPI.md

Optionally use wget instead of curl.