[Tex/LaTex] How to avoid empty ‘thebibliography’ environment (bibtex) if there are no references

bibliographiesbibtexconditionalswarnings

I have a general and central preamble for a lot of similar-style documents (several dozens) and most of the documents have a Bibliography at the beginning, so I call

\bibliographystyle{alphadin}
\bibliography{refs}

in the central preamble to avoid a lot of duplicate code and to be able to change the bibliography style centrally. But sadly, a minority of these documents has an empty bibliography. And these give me a warning about an empty thebibliography environment. But the bigger problem is: the bibliography headline still appears in the pdf output.

Is there a way to only get the bibliography headline and no warning when there is a non-empty bibliography? What would be the correct counters or booleans to address? Or is there an easy-to-use option?

Minmal example:

\documentclass{article}

\begin{document}
  \bibliographystyle{alphadin}
  \bibliography{test}
\end{document}

Run latex, bibtex, latex, latex.
Get for test.bbl

LaTeX Warning: Empty `thebibliography' environment on input line 10.

Entering the "patch" doesn't solve the problem. What I want ist: If there's no \cite{} within the document, don't display the bibliography.

Content of bbl:

\begin{thebibliography}{}

% this bibliography is generated by alphadin.bst [8.2] from 2005-12-21

\providecommand{\url}[1]{\texttt{#1}}
\expandafter\ifx\csname urlstyle\endcsname\relax
  \providecommand{\doi}[1]{doi: #1}\else
  \providecommand{\doi}{doi: \begingroup \urlstyle{rm}\Url}\fi

\end{thebibliography}

Best Answer

A test if the argument of thebibliography is empty

\documentclass{article}
\let\myBib\thebibliography
\let\endmyBib\endthebibliography

\renewcommand\thebibliography[1]{\ifx\relax#1\relax\else\myBib{#1}\fi}
\begin{document}
foo
  \bibliographystyle{alphadin}
  \bibliography{test}
\end{document}
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