%%
%% The LaTeX Companion, 3ed
%%
%% Example 5-4-14 on page I-406 in "truncate --- Truncate text to a given length".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{109.80112pt}

  \setlength\textheight{82pt} %  6 \baselineskip + \topskip

% for the book examples we shorten the vertical spaces
  \makeatletter
  \renewcommand\section{\@startsection{section}{1}{\z@}%
    {-1.25ex \@plus-1ex \@minus-.2ex}%
    {.5ex}%
    {\normalfont\large\bfseries\raggedright}}
  \makeatother

  \addtolength\headsep{-12pt}  % shortened for the book
  \addtolength\footskip{-6pt} % shortened for the book

  \usepackage{microtype}
  \tolerance=3000

%StartShownPreambleCommands
\usepackage[fit,breakwords]{truncate}
\usepackage{kantlipsum,fancyhdr}
\pagestyle{fancy}
\fancyhf{} % --- clear all fields
\fancyhead[RO,LE]{\truncate
     {\headwidth}{\leftmark}}
\fancyfoot[C]{\thepage}
%StopShownPreambleCommands

\begin{document}
\section{Kant on the
         Meaning of Life}
\kant[42]
\end{document}