How to convert a document from article to report?

Question

Is there another way of doing this besides doing a manual find "section"/ replace all with "chapter" (and the same for subsections, subsubsections etc.) ?

Answer 1

The timing of actions is crucial if all levels must be promoted: we have to start from the lowest level up and use \let.

\let\subparagraph\paragraph
\let\paragraph\subsubsection
\let\subsubsection\subsection
\let\subsection\section
\let\section\chapter

Using \renewcommand would turn all section levels into chapters.

However this can work only for very elementary documents without cross references. A complete solution should redefine also the counters and their representation.

\let\thesubparagraph\theparagraph
\let\theparagraph\the\subsubsection
\let\thesubsubsection\thesubsection
\let\thesubsection\thesection
\let\thesection\thechapter

\makeatletter
\let\c@subparagraph\c@paragraph
\let\c@paragraph\c@subsubsection
\let\c@subsubsection\c@subsection
\let\c@subsection\c@section
\let\c@section\c@chapter
\let\p@subparagraph\p@paragraph
\let\p@paragraph\p@subsubsection
\let\p@subsubsection\p@subsection
\let\p@subsection\p@section
\let\p@section\p@chapter
\let\cl@subparagraph\cl@paragraph
\let\cl@paragraph\cl@subsubsection
\let\cl@subsubsection\cl@subsection
\let\cl@subsection\cl@section
\let\cl@section\cl@chapter
\makeatother

Answer 2

I might be a bit overkill, but I would use sed for that instead of pure TeX.