%%
%% Der LaTeX-Begleiter, zweite Auflage (September 2005)
%%
%% Beispiel 3-5-9 von Seite 190.
%%
%% Copyright (C) 2005 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% Uebersetzung: Copyright (C) 2005 Claudia Krysztofiak,
%%    Rebecca Stiels und Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{lb2exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{149.4372pt}

\sloppy
\setlength\marginparsep{20pt}
\addtolength\textwidth{-30pt}
\newcommand\sample{ Text zum Experimentieren
                 mit Zeilennummern.}
\StartShownPreambleCommands
\usepackage{lineno} \linenumbers
% \sample wie zuvor definiert
\newenvironment{numarrows}
    {\renewcommand\makeLineNumber
                  {\llap{\LineNumber$\rightarrow$ }}}
    {\par}
\newenvironment{arrows}{\renewcommand\makeLineNumber
   {\rlap{\hspace{\textwidth} $\leftarrow$}}}{\par}
\StopShownPreambleCommands
\begin{document}
\begin{numarrows}  \sample  \end{numarrows}
\begin{arrows} \sample \sample \end{arrows}
\sample
\begin{numarrows}  \sample  \end{numarrows}
\end{document}
