\documentclass{book}
\usepackage[a4paper,margin=1cm,landscape]{geometry}
\usepackage{multicol}
\newenvironment{flagsAndExplanation}[2]
{
\begin{itemize}
\item \textit{#1} %commandFlags
\begin{itemize}
\item #2 %commandDescription
\end{itemize}
\end{itemize}
}
\newenvironment{commandTemplate}[3]
{
\chapter{#1} %commandName
\section{#2} %sectionName
}
\begin{document}
\begin{multicol}{3}
\newcommand{\mainSomething}{GNU}
\newcommand{\derivedPackage}{coreutils}
\newcommand{\commandName}{ls}
\newcommand{\sectionName}{FilesFilter}
\begin{commandTemplate}{\mainSomething}{\derivedPackage}{\commandName}
\end{commandTemplate}
\newcommand{\commandFlags}{{\texttt{-a, --all}}}
\newcommand{\commandDescription}
{
do not ignore file names that start with '.' .
}
\begin{flagsAndExplanation}{\commandFlags}{\commandDescription}
\end{flagsAndExplanation}
\renewcommand{\commandFlags}{{\texttt{
-d, --directory /
}}}
\renewcommand{\commandDescription}
{
List just the names of directories in current
}
\begin{flagsAndExplanation}{\commandFlags}{\commandDescription}
\end{flagsAndExplanation}
\end{multicol}
\end{document}
Is there something I have done wrong? Why does it work with a simple document, but not on mine?
\documentclassdirective and the instruction\usepackage{multicol}. And the body of the document could be simplified to\begin{document} \begin{multicol}{3} bla bla bla \end{multicol} \end{document}. Everything else is fluff.\newenvironments are working because of sheer luck. They expect two mandatory arguments, the second one being presently grabbed as\parbecause of the empty lines you are leaving in the code.