#! /bin/sh -e

comment="%%" bad=nil
while getopts "c:" o; do
  case $o in
    c) comment=$OPTARG ;;
    *) bad=t ;;
  esac
done
shift $(( $OPTIND - 1 ))
case $bad in t) echo >&2 "usage: $0 [-c COMMENT] [FILE ...]"; exit 2 ;; esac

sed 's/^.*LocalWords: *//' "$@" |
  tr ' ' '\n' | sort -fu | tr '\n' ' ' |
  fold -s -w60 |
  sed "s/^/$comment LocalWords: /; s/[[:space:]]*\$//"
echo