Editing a citation style (verbose-ibid)

Question

a lot of questions are asked regarding more or less my topic, but I'm unable to find answers. I'm using overleaf and I would like to be able to generate the code of the citation style verbose-ibid to be able to edit it. I started using Latex a few days ago and don't know anything about it, but I am quite ok modifying a Zotero style for instance.

\documentclass[12pt]{article}       
\usepackage[utf8]{inputenc} 
\usepackage[greek, french]{babel}
\usepackage[T1, T2A]{fontenc}   
\usepackage{setspace}
\usepackage[margin=3cm]{geometry} 



%Bibliographie
%----------------------------------------------------------------
\usepackage{csquotes}
\usepackage[style=verbose-ibid,backend=bibtex]{biblatex}
\bibliography{\jobname.bib}

\begin{filecontents}{\jobname.bib}
@book{key,
   author = {Author, A.},
   year = {2001},
   title = {Title},
   publisher = {Publisher},
 }
 \end{filecontents}

 \begin{document}

 \footcite{key}

 \printbibliography

 \end{document}

Answer 1

The code for biblatex styles can be found in <style>.bbx (bibliography style code) and <style>.cbx (citation style code).

In your case the relevant files are verbose-ibid.bbx and verbose-ibid.cbx. You can find these files on your machine with kpsewhich verbose-ibid.bbx and kpsewhich verbose-ibid.cbx, respectively.

All relevant files are also on CTAN in https://www.ctan.org/tex-archive/macros/latex/contrib/biblatex/latex or http://mirrors.ctan.org/macros/latex/contrib/biblatex/latex/ and its subdirectories, and on GitHub in https://github.com/plk/biblatex/blob/dev/tex/latex/biblatex/ and subdirectories.

You'll find that verbose-ibid.bbx immediately sends you off to authortitle.bbx. So the first interesting file is authortitle.bbx.

verbose-ibid.cbx on the other hand contains a complete citation style.

Additional to the style-specific files, you will always want to have standard.bbx and biblatex.def handy. standard.bbx is loaded by all standard biblatex styles and biblatex.def is loaded by all styles automatically. The biblatex documentation is also helpful.

biblatex styles are modular and that means that you may have to chase down definitions of the involved macros in several different files.

---

To answer some of the concrete questions from an earlier version of your question.

1. You can change the default punctuation from a full stop to a comma with

   \renewcommand*{\newunitpunct}{\addcomma\space}
   

   This will also apply to the bibliography at the end, so if you want a different layout there you may have to use \AtBeginBibliography

2. Is more tricky, I didn't do anything here because the desired output was not clear to me. I suggest you ask a new question with well-defined desiderata.

3. Could be achieved with the option

   giveninits=true
   

   Again, if the behaviour should be different in the bibliography, you need to do extra work.

4. The citepages option could help you here. See the verbose-ibid style documentation. Maybe you want

   citepages=omit
   

   or maybe the more radical citepages=suppress or the fancy citepages=separate.

Your document could look like this

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{csquotes}

\usepackage[style=verbose-ibid, backend=biber, giveninits=true, citepages=omit]{biblatex}

\addbibresource{biblatex-examples.bib}

\renewcommand*{\newunitpunct}{\addcomma\space}

\begin{document}
Lorem\autocite[381]{sigfridsson}
ipsum\autocite[200]{spiegelberg}
\printbibliography
\end{document}