Locally setting the line width in a paragraph

Question

How can I make a specific paragraph have a specific line width?

Answer 1

Use \parbox{<linewidth>}{<content>} for the paragraph. Alternatively you can use the very similar minipage environment which also takes the line width as first argument. However, both do not allow page breaks in the paragraph. Also have a look on the quote and quotation environments which narrow the paragraph width.

Answer 2

The method with \leftskip and \rightskip doesn't work if the reduced width part of the document contains lists. In this case it's best to define an environment based on list:

\usepackage{keyval}
\makeatletter
\define@key{setpar}{left}[0pt]{\leftmargin=#1}
\define@key{setpar}{right}[0pt]{\rightmargin=#1}
\define@key{setpar}{both}{\leftmargin=#1\relax\rightmargin=#1}
\makeatother

\newenvironment{narrow}[1][]
  {\list{}{\setkeys{setpar}{left,right}%
     \setkeys{setpar}{#1}%
     \listparindent=\parindent
     \topsep=0pt
     \partopsep=0pt
     \parsep=\parskip}\item\relax\hspace*{\listparindent}\ignorespaces}
  {\endlist}

One can specify the settings in the following ways, that should be easily understood:

  \begin{narrow}[left=1cm]
  \begin{narrow}[right=2cm]
  \begin{narrow}[both=1cm]
  \begin{narrow}[left=2cm,right=1cm]

and lists inside the environment will work properly.

Answer 3

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[english]{babel}
\usepackage{blindtext}
\begin{document}
\blindtext

\leftskip=1cm
\blindtext

\rightskip=1cm
\blindtext

\leftskip=0pt\rightskip=0pt
\blindtext
\end{document}

Answer 4

Good feature: The paragraph can span across pages and be enclosed by a fancy frame.

\documentclass{article}
\usepackage{framed,lipsum,xcolor}

\renewenvironment{leftbar}[1][\hsize]{%
\def\FrameCommand{{\color{red}\vrule width 3pt}\hspace{0pt}\fboxsep=\FrameSep\colorbox{yellow}}%
\MakeFramed{\hsize#1\advance\hsize-\width\FrameRestore}}
{\endMakeFramed}

\begin{document}
\lipsum[1]
\begin{leftbar}[0.5\linewidth]
\lipsum[1-3]
\end{leftbar}
\lipsum[3]
\end{document}