File copy without expansion

Question

What is the command for file copy? I want to copy the contents of one file into another without any command expansion. In a command line driven operating system one would use

copy source target

I tried reading the contents of one file into a variable and the writing it into the target:

\CatchFileDef{\OriginalF}{\jobname.sc0}{}
\newwrite\hcOutputStreamF
\immediate\openout\hcOutputStreamF=\jobname.sc1
\immediate\write\hcOutputStreamF{\OriginalF}
\immediate\closeout\hcOutputStreamF

but it expands the TeX commands saved in the original file.

Answer 1

Here's a Plain TeX solution that uses the ε-TeX extension \readline. It copies its source to \jobname.copy.

\newread\in
\openin\in=\jobname.tex
\newwrite\out
\immediate\openout\out\jobname.copy
\endlinechar-1
\loop \unless\ifeof\in
        \readline\in to\l
        \immediate\write\out{\l}
\repeat
\immediate\closeout\out
\closein\in
\end

Answer 2

The verbatimcopy package provides the command \VerbatimCopy which seems to do exactly what you are looking for. It doesn't seem to work for "binary" (i.e., non-text) files, though.

\documentclass{scrartcl}
\pagestyle{empty}

\usepackage{verbatimcopy}
\usepackage{graphicx}

\begin{document}
  \VerbatimCopy{input.tex}{input.tmp}
  \input{input.tmp}

  % This doesn't work for binary files:
  %\VerbatimCopy{img.png}{img2.png}
  %\includegraphics{img2.png}
\end{document}

I have added a compilable example to GitHub.

Answer 3

You were very close in your original question; just replace

\immediate\write\hcOutputStreamF{\OriginalF}

with

\immediate\write\hcOutputStreamF{\unexpanded\expandafter{\OriginalF}}

and I think you'll get what you're after.

Answer 4

This one comes fairly close. The trick is to make every character non-special while copying.

\def\everythingother{%
  \count255=0
  \loop\catcode\count255=12
    \advance\count255 1
    \ifnum\count255<256 \repeat}

\newread\infile
\newwrite\outfile
\newif\ifgo

\begingroup
\obeylines
\gdef\copyfileverbatim#1#2{%
 \begingroup\everythingother
 \obeylines
 \def^^M{}
 \immediate\openin\infile=#1
  \immediate\openout\outfile=#2
  \loop
    \read\infile to\data
    \immediate\write\outfile{\data}%
    \ifeof\infile\infile\gofalse\else\gotrue\fi
    \ifgo\repeat
  \closein\infile
  \immediate\closeout\outfile
  \endgroup}
\endgroup

\copyfileverbatim{tt.in}{tt.out}
\bye

One remaining problem: any control character in the input will be copied to its TeX equivalent, so a backspace character becomes ^^H. I have no fix for that.