Underline a page head

Question

I have the following code:

\documentclass{article}

\makeatletter
\renewcommand\ps@headings{
  \def\@evenhead{foo bar}
  \def\@oddhead{foo bar}
}
\makeatother
\begin{document}
\pagestyle{headings}

\section{Introduction}
foo bar baz

\end{document}

(This is just an example. The real document is a bit more complicated...)

How can I have a rule below the »foo bar« header?

I'd like to get something like this:

That is: a rule size \hsize. I don't want to use fancyhdr.

Edit: More requirements: I need to configure the rule thickness and the distance between the words »foo ... bar« and the horizontal rule.

Answer 1

You can just under line them.

\documentclass{article}
\usepackage[normalem]{ulem}

\makeatletter
\renewcommand\ps@headings{
  \def\@evenhead{\uline{foo bar}}
  \def\@oddhead{\uline{foo bar}}
}
\makeatother
\begin{document}
\pagestyle{headings}

\section{Introduction}
foo bar baz
\clearpage
\section{Introduction}
foo bar baz

\end{document}

You can change the thickness and depth of the rule by

\setlength{\ULdepth}{2ex}
\renewcommand{\ULthickness}{2pt}

Same with soul:

\usepackage{soul}

\makeatletter
\renewcommand\ps@headings{%
  \def\@evenhead{\ul{foo bar}}%
  \def\@oddhead{\ul{foo bar}}%
}
\makeatother

The depth and thickness can be changed by

\setul{2ex}{2pt}

Sorry about the bad boxes. I am not responsible :-)

Answer 2

You can simply add a rule after the box that holds the heading:

\documentclass{article}

\makeatletter
\def\myhrule{\vskip1ex\hrule height 5pt}
\renewcommand\ps@headings{%
  \def\@evenhead{foo\hfill bar\aftergroup\myhrule}%
  \def\@oddhead{foo\hfill bar\aftergroup\myhrule}%
}
\makeatother
\begin{document}
\pagestyle{headings}

\section{Introduction}
foo bar baz

\end{document}

Or if you have color loaded

\documentclass{article}

\usepackage{color}

\makeatletter
\def\myhrule{\vskip1ex\hrule height 5pt}
\renewcommand\ps@headings{%
  \def\@evenhead{foo\hfill bar\aftergroup\aftergroup\aftergroup
\aftergroup\aftergroup\aftergroup\aftergroup\myhrule}
  \def\@oddhead{foo\hfill bar\aftergroup\aftergroup\aftergroup
\aftergroup\aftergroup\aftergroup\aftergroup\myhrule}
}
\makeatother
\begin{document}
\pagestyle{headings}

\section{Introduction}
foo bar baz

\end{document}

Answer 3

My \myhrule for rules in headers looks slight different than David's. The position of the heading text doesn't depend on the depth of the text. And, of course, I needn't any additional package.

\makeatletter
\def\myhrule{\lower1ex\null\vadjust{\hrule}}
\renewcommand\ps@headings{%
  \def\@evenhead{foo\hfill bar\myhrule}%
  \def\@oddhead{foo\hfill bar\myhrule}%
}
\makeatother