Extract floats and read an external aux file to get hyperref infos in captions

My purpose is to use the endfloat package to extract all figures (with their captions) in a separate pdf file. I want to do it with a script combining bash command line and emacs-lisp.

I want to do that because, in my copy editor work, I need to compare the figures (and their captions) of the accepted version with the formatted version ones. I know this is not the perfect solution (but I think it should works in most cases) so different/better ideas are welcome.

This is my MWE (the mydoc.tex file):

documentclass[11pt]{article}
pagestyle{empty}
usepackage{graphicx}
usepackage{blindtext}
usepackage[colorlinks=true,
,citecolor=blue
,linkcolor=blue]{hyperref}

begin{document}
section{Section 1}
label{section1}
blindtext

begin{figure}[t]
    centering
    includegraphics[width=.49columnwidth]{example-image-a}
    caption{Dummy caption cite{1} (see figure~ref{fig3} in
      section~ref{section3}).label{fig1}}
end{figure}

section{Section 2}
label{section2}
blindtext

begin{figure}[t]
    centering
    includegraphics[width=.49columnwidth]{example-image-b}
    caption{Dummy caption cite{2} (see figure~ref{fig1} in
      section~ref{section1}).label{fig2}}
end{figure}

section{Section 3}
label{section3}
blindtext
blindtext

begin{figure}[t]
    centering
    includegraphics[width=.49columnwidth]{example-image-c}
    caption{Dummy caption cite{3} (see figure~ref{fig2}
      section~ref{section2}).label{fig3}}
end{figure}

begin{thebibliography}{9}

bibitem{1}
Dummy bibibtem

bibitem{2}
Dummy bibibtem

bibitem{3}
Dummy bibibtem

end{thebibliography}
end{document}

1. First of all I want to generate and backup the .aux file. I’ll compile with:

   latexmk -pdf mydoc.tex; cp mydoc.aux mydoc-bk.aux
   

2. Then I’ll compile with:

   pdflatex "nofiles"
   "AtBeginDocument{usepackage[figuresonly,nolists]{endfloat}}"
   "nonstopmode"
   "input{mydoc.tex}"
   

to generate the mydoc.fff file that contains:

begin{figure}[t]
  centering
  includegraphics[width=.49columnwidth]{example-image-a}
  caption{Dummy caption cite{1} (see figure~ref{fig3} in
    section~ref{section3}).label{fig1}}
end{figure}
efloatseparator

begin{figure}[t]
  centering
  includegraphics[width=.49columnwidth]{example-image-b}
  caption{Dummy caption cite{2} (see figure~ref{fig1} in
    section~ref{section1}).label{fig2}}
end{figure}
efloatseparator

begin{figure}[t]
  centering
  includegraphics[width=.49columnwidth]{example-image-c}
  caption{Dummy caption cite{3} (see figure~ref{fig2}
    section~ref{section2}).label{fig3}}
end{figure}
efloatseparator

Now I create a new file: mynewdoc.tex (this is meant to be a temporary solution):

documentclass[11pt]{article}
pagestyle{empty}
usepackage{graphicx}
usepackage{blindtext}
usepackage[colorlinks=true,
,citecolor=blue
,linkcolor=blue]{hyperref}

defefloatseparator{clearpage}

begin{document}

input{mydoc.fff}

end{document}

That I’ll compile with:

pdflatex mynewdoc.tex

My question is: can I force (pdf)latex to compile using the backup .aux file so to get the correct refs (obviously without working links) in my final pdf?

I think that should be disabled the writing of the .aux file in some way because some of the labels are already defined in the external .aux file.

My solution. I resolved by renaming the .aux I want to be read in mynewdoc.aux and putting nofiles in the preamble.

Alternative solution. I also found this alternative solution using the xcomment package. After generating the correct .aux file I will compile with:

pdflatex -jobname=mydoc 
"RequirePackage{xcomment} xcomment{figure}"
"nofiles"
"AtBeginDocument{letoldendfigureendfigure"
"defendfigure{oldendfigureclearpage}}"
"input{mydoc.tex}"

I’ll have a warning becouse the nofiles command does not take effect (can anybody help me with that?) but the generated pdf file will be ok.