curl -s https://make-linux-fast-again.com | awk '{ print "GRUB_CMDLINE_LINUX_DEFAULT=\"" $0 "\"" }' >> grub.cfg
OK cool. Thanks for the explanation, that makes sense why it's empty then!
I definitely didn't get it. I take back what I said :) It did lead me to poking around the Linux kernel docs so that's not a bad way to start the day!