RFCs are information & communication documents so important that some of them have become Internet standards. I like keeping local copies of important documentation so I downloaded the RFCs with:

#!/usr/bin/env bash

url=https://tools.ietf.org/rfc/rfc
for n in {0..9000}; do
    (
        if wget -q "$url$n.txt" &> /dev/null; then
            echo "Downloading $url$n.txt"
        fi
    ) &

    # download rfc's in batches of 10
    while test $(jobs -p | wc -w) -ge 10; do wait -n; done
done

then define a man-like function:

rfc() (
    file=$HOME/rfc$1
    [ -f $file ] && less $file || echo "Could not find RFC$1"
)

now rfc 20 will open RFC20 in the terminal.