Problem with headings and book class

Question

I have a the following document which uses the book class. For some reason, the page number is, on the first page, at the bottom of the page and centered (article like footer). The next page has the number up and on the left (with the chapter title on the right): book like heading.

Why do I have two different ways to show the page number? I would like to have the normal book class heading (i.e. the page 2 heading) for the whole document.

MWE:

\documentclass[12pt,twoside,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{setspace}
\usepackage{graphicx} 
\usepackage{lmodern}
\usepackage{xspace}
\title{}
\author{}
\usepackage[english]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}
\usepackage{lipsum}
\begin{document}
%\maketitle
\tableofcontents
\onehalfspacing

\frontmatter 

%\include{fichiers/intro}

\mainmatter

%\include{fichiers/chap1}
%\include{fichiers/chap2}
%\include{fichiers/chap3}
%include{fichiers/chap4}
%include{fichiers/ccl}

\appendix
\backmatter 


\end{document}

Answer 1

This is the default behavior for first pages of chapters.

If you want to change this, simply add the following lines in your preamble (package etoolbox is required):

\patchcmd{\chapter}
  {\thispagestyle{plain}}
  {}
  {}
  {}

MWE:

\documentclass[12pt,twoside,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{xspace}
\title{}
\author{}
\usepackage[english]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}
\usepackage{lipsum}
\usepackage{etoolbox}
\patchcmd{\chapter}
  {\thispagestyle{plain}}
  {}
  {}
  {}

\begin{document}
%\maketitle
\tableofcontents
\onehalfspacing

\frontmatter

%\include{fichiers/intro}

\mainmatter

%\include{fichiers/chap1}
%\include{fichiers/chap2}
%\include{fichiers/chap3}
%include{fichiers/chap4}
%include{fichiers/ccl}

\appendix
\backmatter


\end{document} 

Output:

Answer 2

Here is another way, noting that the page style headings is used by the book document class. Add these lines to your preamble:

\makeatletter
\let \ps@plain \ps@headings
\makeatother

Full code:

\documentclass[12pt,twoside,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{xspace}
\title{}
\author{}
\usepackage[english]{babel}
\usepackage{csquotes}
\usepackage[colorlinks]{hyperref}
\usepackage{lipsum}

\makeatletter
\let \ps@plain \ps@headings
\makeatother
\begin{document}
%\maketitle
\tableofcontents
\onehalfspacing

\frontmatter

%\include{fichiers/intro}

\mainmatter

%\include{fichiers/chap1}
%\include{fichiers/chap2}
%\include{fichiers/chap3}
%include{fichiers/chap4}
%include{fichiers/ccl}

\appendix
\backmatter


\end{document}