marlin/buildroot/share/git/mfinit

#!/usr/bin/env bash
#
# mfinit
#
# Create the upstream remote for a forked repository
#

REPO=$(git remote get-url origin 2>/dev/null | sed -E 's/.*\/(.*)\.git/\1/')

if [[ -z $REPO ]]; then
  echo "`basename $0`: No 'origin' remote found." 1>&2 ; exit 1
fi

git remote add upstream "git@github.com:MarlinFirmware/$REPO.git"

git fetch upstream