sed_inplace_arg = "-i"
sed_inplace_arg_darwin = "-i ''"
sed_extended_re_arg = "-r"
sed_extended_re_arg_darwin = "-E"
sed () {
   # Sed portability notes
   # - SuSv3
   #   - Only -e, -f, and -n are standard options
   # - Linux
   #   - -i argument is of the form -i[ext]
   #   - extended regular expressions argument is -r
   # - Mac OSX
   #   - -i argument is of the form -i [ext]
   #   - extended regular expressions argument is -E
   #
   # Here we support a limited subset of the available sed capabilities,
   # ensuring that all those supported by this function can be utilized
   # regardless of the current platform.
   #
   # We accept -n, -e, -f, and -i with no backup extension.  We support
   # extended regular expressions using the -r argument.  Note that extended
   # regular expressions support may not be retained, depending upon the
   # capabilities of the other platforms we wish to support, and we may need
   # to reimplement -i internally in this script on some platforms.

   args=`getopt ner:f:i "$@"` || return 1
   set -- $args

   opts=""
   while [ $# -gt 0 ]; do
      case $1 in
         -i)
            opts="$opts ${sed_inplace_arg}"
            ;;
         -r)
            opts="$opts ${sed_extended_re_arg}"
            ;;
         --)
            shift
            break
            ;;
         *)
            opts="$opts \"$1\""
            ;;
      esac
      shift
   done
   eval command sed $opts "$@"
}