Trim margins of the entire document (by command line)

Question

Is there a way to trim the margins of the entire document by LaTeX? I need to do that temporarily, to make more comfortable my typesetting work. I figured out to pass this option by command line with the \AtBeginDocument technique but a preamble solution is also welcome.

To better explain my purposes I'd like to get the same result that I can achieve with the bash command (that here works because of the coloured page):

pdfcrop --margins '-50 -50 -50 -50' mydoc.pdf mydoc.pdf

E.g. for the code:

\documentclass[a4paper,11pt]{article}

%% \usepackage{xcolor}
%% \pagecolor[HTML]{E4EDE9}

\usepackage{blindtext}

\begin{document}

\section{Section}
\blindtext

\blindtext

\blindtext\footnote{\blindtext}

\end{document}

I want to change the layout from:

NOTE. I obtain this layout by passing the color option by command line:

pdflatex '\AtBeginDocument{\RequirePackage{xcolor} \pagecolor[HTML]{E4EDE9}} \input{Latex.tex}'

(I want to thank Thérèse for this very eye-relaxing background color)

to:

An okular specific solution is welcome but, since I use many viewers, I prefer a LaTeX solution.

NOTE2. I need a solution that does not change the text layout. I need only to trim the pdf as it stands.

---

SOLUTION

I want to share the solution that works in my case (thanks to Steven B. Segletes). This is the code for a command line cropped and coloured compilation:

pdflatex '\AtBeginDocument{\newlength\DX \DX=3cm \paperwidth=\dimexpr\paperwidth-\DX\relax \hoffset=\dimexpr\hoffset-.5\DX\relax \newlength\DY \DY=3cm \paperheight=\dimexpr\paperheight-\DY\relax \voffset=\dimexpr\voffset-.1\DY-.5\footskip\relax \RequirePackage{xcolor} \pagecolor[HTML]{E4EDE9}} \nonstopmode\input{mydoc.tex}'

NOTE ADDED. After TeX Live 2020 October update this solution needs an update: Trim margins of the entire document by command line (after TeX Live 2020 update)

Answer 1

Here I take the baseline article documentclass (using the pass option of geometry) and change the \paperwidth and \paperheight by the specified amount and then associated margins (actually \hoffset and \voffset) by one half of the page change dimensions.

\documentclass{article}
\usepackage{lipsum}
\usepackage[pass]{geometry}
\newlength\DX
\DX=3.5in
\paperwidth=\dimexpr\paperwidth-\DX\relax
\hoffset=\dimexpr\hoffset-.5\DX\relax
\newlength\DY
\DY=2.8in
\paperheight=\dimexpr\paperheight-\DY\relax
\voffset=\dimexpr\voffset-.5\DY-.5\footskip\relax
\begin{document}
\lipsum[1-10]
\end{document}

Without any changes:

Answer 2

Why don't you use crop package?!

As David Carlisle said you can also use geometry package, but I prefer crop in this case; for more details see the package's manual.

with setting width and height you can achieve your desired margins.

\documentclass[a4paper,11pt]{article}
\usepackage[a4,center,noinfo,cross, width=13.5cm,height=22.5cm]{crop}
\usepackage{blindtext}

\begin{document}

\section{Section}
\blindtext
\blindtext
\blindtext\footnote{\blindtext}
\end{document}

Answer 3

You can try

\AtBeginDocument{%
\edef\mt{\the\textwidth}%
\edef\mtt{\the\textheight}%
\RequirePackage{geometry}%
\geometry{paperwidth=\dimexpr\mt+1cm\relax,
paperheight=\dimexpr\mtt+1cm\relax,margin=.5cm}
\RequirePackage{xcolor} 
\pagecolor[HTML]{E4EDE9}}

\documentclass[a4paper,11pt]{article}

\usepackage{blindtext}

\begin{document}

\section{Section}
\blindtext

\blindtext

\blindtext\footnote{\blindtext}

\end{document}