Compiling from chapter

Question

I'm new to LaTeX. I created a new document with the following structure

\documentclass{scrreprt}
\usepackage[english]{babel}
\usepackage{appendix}

% ... %

\begin{document}

\maketitle
\tableofcontents

\input{./content/1-Introduction}
% ... %
\input{./content/7-Appendix}

\end{document}

When I compile it from the "main" file, everything works. But when I compile it from one of my chapter files, it says:

! Undefined control sequence.
l.1 \chapter
! LaTeX Error: Missing \begin{document}.

A chapter looks like this:

\chapter{My Chapter}
% ... %
\section{...}
% ... %

Answer 1

Every LaTeX document must start with \documentclass, include \begin{document} and end with \end{document}. Your chapter files don't have that so they can't compile by themselves.

But if you use \include instead of \input in the main file, then you can select parts to compile by using \includeonly in the preamble.

For example, use \include{chapters/first} \include{chapters/second} in the main document, and then add a line \includeonly{chapters/first} to the preamble and compile the main document.

Answer 2

This shows the \includeonly approach, specifying only some of the files, although 'all' of them are given in the document as \include{chapter1.tex} etc.

\documentclass{scrreprt}
\usepackage[english]{babel}
\usepackage{appendix}

\usepackage{blindtext}

\usepackage{filecontents}

\begin{filecontents}{chapter1.tex}
\chapter{This is chapter one}
\blindtext

\end{filecontents}

\begin{filecontents}{chapter2.tex}
\chapter{This is chapter two}
\blindtext

\end{filecontents}

\begin{filecontents}{chapter3.tex}
\chapter{This is chapter three}
\blindtext

\end{filecontents}


\title{Some title}

% ... %

\includeonly{chapter1,chapter2}
\begin{document}

\maketitle
\tableofcontents


\include{chapter1}
\include{chapter2}
\include{chapter3}

%\input{./content/1-Introduction}
% ... %
%\input{./content/7-Appendix}

\end{document}

Answer 3

You should write every chapter in a separate file (with \chapter issued right after \begin{document}), then load the package docmute in the main file: this package suppress \end{document} and all before \begin{document} included when you \input the chapter files.

Example:

ch01.tex:

\documentclass{book}
\begin{document}
\chapter{Chapter One}
...text...
\end{document}

ch02.tex:

\documentclass{book}
\begin{document}
\chapter{Chapter Two}
...text...
\end{document}

main.tex:

\documentclass{book}
\usepackage{docmute}
\begin{document}
\input{ch01}
\input{ch02}
\end{document}