Possible Duplicate:
Verbatim environment that can break too long lines?
How to prevent contents of verbatim text from running off the page?
\documentclass[12pt,a4paper]{article}
\begin{document}
Need to add {\tt contrib}
\begin{verbatim}
peter@debpet:~$ gksudo mousepad /etc/apt/sources.list
#You commented out deb-src in the process too as it is not needed if you just apt-get and use Synaptic; it's only for expert users who want to inspect src and compile from scratch
# deb cdrom:[Debian GNU/Linux testing _Wheezy_ - Official Snapshot i386 NETINST Binary-1 20110904-21:43]/ wheezy main
deb http://mirror.optus.net/debian/ wheezy main {\bf contrib} non-free
#deb-src http://mirror.optus.net/debian/ wheezy main
deb http://security.debian.org/ wheezy/updates main
#deb-src http://security.debian.org/ wheezy/updates main
\end{verbatim}
\end{document}
