I have
\documentclass[twocolumn]{article}
\begin{document}
\rule{\textwidth}{1pt}
\end{document}
However, this line crosses the two columns. I just want the line cross the first column.
[Tex/LaTex] Horizontal line for two column
line-spacing
Related Solutions
You are changing the font size to \Huge inside a group, but the group ends before the paragraph, so the line spacing for \Huge has no effect; to correct this, you must end the paragraph (using \par, for example) before closing the group:
\documentclass[10pt,a4paper]{article}
\usepackage[portuguese]{babel}
\usepackage[latin1]{inputenc}
\usepackage[pdftex]{graphicx}
\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\begin{document}
\begin{titlepage}
\begin{center}
% Upper part of the page
%\includegraphics[width=0.15\textwidth]{./logo}\\[1cm]
\textsc{\large Department}\\[0.5cm]
\textsc{\Large University}\\[3.5cm]
\textsc{\Large Proposal bla bla}\\[1.5cm]
% Title
\HRule \\[0.4cm]
{\Huge \bfseries Proposal title proposal title proposal title proposal title proposal title proposal title\par}
\vspace{0.4cm}
\HRule \\[1.5cm]
% Author and supervisor
\begin{minipage}{0.4\textwidth}
\begin{flushleft} \large
\emph{Autor:}\\
John Smith
\end{flushleft}
\end{minipage}
\begin{minipage}{0.4\textwidth}
\begin{flushright} \large
\emph{Orientador:} \\
Dr.~Albert \textsc{Einstein}
\end{flushright}
\end{minipage}
\vfill
% Bottom of the page
{\large \today}
\end{center}
\end{titlepage}
\end{document}
which produces:
If you want to increase even more the line spacing, you can change \linespread for the title; a little example using \linespread{1.5} (notice again the \par command necessary for the change to have effect):
\documentclass[10pt,a4paper]{article}
\usepackage[portuguese]{babel}
\usepackage[latin1]{inputenc}
\usepackage[pdftex]{graphicx}
\newcommand{\HRule}{\rule{\linewidth}{0.5mm}}
\begin{document}
\begin{titlepage}
\begin{center}
% Upper part of the page
%\includegraphics[width=0.15\textwidth]{./logo}\\[1cm]
\textsc{\large Department}\\[0.5cm]
\textsc{\Large University}\\[3.5cm]
\textsc{\Large Proposal bla bla}\\[1.5cm]
% Title
\linespread{1.5}
\HRule\\
{\Huge\bfseries Proposal title proposal title proposal title proposal title proposal title proposal title\par}
\vspace*{0.4cm}
\HRule\\[1.5cm]
\linespread{1}
% Author and supervisor
\begin{minipage}{0.4\textwidth}
\begin{flushleft} \large
\emph{Autor:}\\
John Smith
\end{flushleft}
\end{minipage}%
\begin{minipage}{0.4\textwidth}
\begin{flushright} \large
\emph{Orientador:} \\
Dr.~Albert \textsc{Einstein}
\end{flushright}
\end{minipage}
\vfill
% Bottom of the page
{\large \today}
\end{center}
\end{titlepage}
\end{document}
As an aside, I think you should rather use package geometry for setting the page layout dimensions.
Anyway, according to res.cls the length \sectionwidth is used for the stuff in the margin. So:
\documentclass[margin]{res}
\usepackage{amsmath}
\setlength{\textwidth}{6in} % set width of text portion
\addtolength{\textheight}{1.8in}
\addtolength{\voffset}{-0.75in}
\addtolength{\hoffset}{-0.5in}
\setlength{\parskip}{0.1in }
\usepackage[hidelinks]{hyperref}
\begin{document}
\newcommand*{\desicenteredline}[1]{%
\ifhmode\expandafter\\\else\noindent\fi
\hspace*{-\sectionwidth}%
\hbox to \dimexpr\sectionwidth+\linewidth\relax{\hss #1\hss}\hskip0pt\relax}
% Center the name over the entire width of resume:
%\moveleft.6\hoffset\centerline{\Large\bf Ajjhjghf Dkjggi}
\desicenteredline{\Large\bf Ajjhjghf Dkjggi}
\smallskip
%address line
%\moveleft.6\hoffset\centerline{\underline{\href{mailto:blahblah.edu}{blahblha.edu} $\bullet$ Ph.:+kjhghjkjhg $\bullet$ \href{www.blahblah.com}{blahblha.com} $\bullet $bhak bhak bahkrd rd, \#poi, bibibi xxxxx}}
remove me (test)\desicenteredline{\underline{\href{mailto:blahblah.edu}{blahblha.edu} $\bullet$ Ph.:+kjhghjkjhg $\bullet$ \href{www.blahblah.com}{blahblha.com} $\bullet $bhak bhak bahkrd rd, \#poi, bibibi xxxxx}}remove me (test)
% adding a line accross the full page
\desicenteredline{\hrulefill}
\begin{resume}
\section{OBJECTIVE} Seeking an jkhasjkdh jhasd ah jlkahds lalkhkljahd kjahd akjh dalkjh lakjh kjhda ajklhsd ajkshd alkjdsh aljkhd ajkshd ajkshd lajkdh alkjshd alskjdh alkjshd lakjsdh.
\section{EDUCATION}
{\bf University of XXXXXX} \hfill (2012 - 2014) \\
{\sl blbl, blblbl Engineering {\bf GPA: } }
\end{resume}
\end{document}
Best Answer
Use
\linewidthfor the width of the current environment (in this case, the current column). Use\textwidthfor the width of the whole text block on the page.