Shell script for .(bash|zsh)rc: file path -> github link

ghlink.sh

# print the github url for a file at the current branch
ghlink() {
  local file="$1"
  if [ -z "$file" ]; then
    echo "usage: ghlink <path>" >&2
    return 1
  fi

  # remote url -> owner/repo, handling both ssh and https
  local slug
  slug=$(git config --get remote.origin.url | sed -E '
    s#^git@[^:]+:##;
    s#^https?://[^/]+/##;
    s#\.git$##
  ')

  local branch rel
  branch=$(git rev-parse --abbrev-ref HEAD)
  rel=$(git ls-files --full-name "$file" 2>/dev/null \
    || realpath --relative-to="$(git rev-parse --show-toplevel)" "$file")
  echo "https://github.com/$slug/blob/$branch/$rel"
}