[Tex/LaTex] Compile to PDF file with different name than the source

macrospdf

I have a latex document containing some problems and their solutions. I also have a macro \excludecomment{sol} which if uncommented, excludes the solution environments. (Similar command is there for prob environment.)

The general question is whether I can include a command in these macros or otherwise so that depending on whether the macro is active or not is reflected in the filename of the PDF file (e.g., by adding a _sol to the filename when the solutions are present.)

Best Answer

You can't change the name of the output files/the name of the .pdf file during the TeX run/LaTeX run.

The reason is:

The output files are created anew and opened for writing right at the beginning of the TeX run/LaTeX run.
(E.g., the .log file is created anew and opened for writing right after starting the tex-executable or latex-executable. E.g., the .pdf file is created anew and opened for writing when shipping out the very first page of the document. )
The output files (and thus also the .pdf file) are left open for writing until the end of the TeX run/LaTeX run.
With most computer platforms you can't change the name of a file while that file is open for writing.

But with most TeX-platforms you can run tex-binaries/executables with command line options.

One of these options is the option -jobname.

If you have the main .tex-file foo.tex and compile it by running latex from the command line as

pdflatex --jobname=bar foo.tex

, you won't get the output files foo.aux, foo.log and foo.pdf, etc, but you will get output files bar.aux, bar.log and bar.pdf, etc.

Also the primitive \jobname won't deliver the phrase foo in this case but will deliver the phrase bar.

You can't use a macro for changing the names of output files during the LaTeX run but you can go the other direction:

Create a macro which examines whether the expansion of \jobname contains some specific phrase and forks accordingly. Be aware that \jobname spits out explicit space tokens of category code 10(space) and explicit character tokens of category code 12(other).

Example:

Save the following example as test.tex :

\documentclass{article}
\usepackage{comment}

\begingroup    
\makeatletter
%%----------------------------------------------------------------------
%% Check whether argument is empty:
%%......................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is empty>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is not empty>}%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
\long\def\UD@CheckWhetherNull#1{%
  \romannumeral0\expandafter\@secondoftwo\string{\expandafter
  \@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
  \@secondoftwo\string}\expandafter\@firstoftwo\expandafter{\expandafter
  \@secondoftwo\string}\expandafter\expandafter\@firstoftwo{ }{}%
  \@secondoftwo}{\expandafter\expandafter\@firstoftwo{ }{}\@firstoftwo}%
}%
%%----------------------------------------------------------------------
%% Check whether expansion of \jobname contains no phase "_sol"
%%......................................................................
%% \UD@CheckWhetherNoSolInJobname{<Tokens to be delivered in case that
%%                                 \jobname contains no phrase "_sol">}%
%%                               {<Tokens to be delivered in case that
%%                                 \jobname contains the phrsae "_sol">}%
\def\UD@GobbleToSol{_sol}%
\@onelevel@sanitize\UD@GobbleToSol
\edef\CheckWhetherNoSolInJobname{%
  \noexpand\expandafter\noexpand\UD@CheckWhetherNull
  \noexpand\expandafter{\noexpand\UD@GobbleToSol\jobname\UD@GobbleToSol}%
}%
\expandafter\long\expandafter\def
\expandafter\UD@GobbleToSol\expandafter#\expandafter1\UD@GobbleToSol{}%
\CheckWhetherNoSolInJobname{%
  \endgroup
  \newcommand\CheckWhetherNoSolInJobname[2]{#1}%
}{%
  \endgroup
  \newcommand\CheckWhetherNoSolInJobname[2]{#2}%
}%
%% \makeatother not needed. Instead the group is closed.
%%----------------------------------------------------------------------

\CheckWhetherNoSolInJobname{%
  \excludecomment{sol}%
}{%
  \includecomment{sol}%
}%

\begin{document}

Expansion of \verb|\jobname| is: \texttt{\jobname}

\texttt{\string\jobname} does
\CheckWhetherNoSolInJobname{%
  not%
}{%
  indeed%
}
contain the phrase \verb|_sol|.

Thus solutions
\CheckWhetherNoSolInJobname{%
  are not included%
}{%
  get included also%
}.

\bigskip

This is the question.
\begin{sol}

This is the answer.
\end{sol}

\end{document}

Compiling from the command line via pdflatex test.tex yields test.pdf which looks like this:

Compiling from the command line via pdflatex --jobname=test_sol test.tex yields test_sol.pdf which looks like this:

Another approach could be:

File test_sol.tex:

\newcommand\solutioninorexclude{%
  \includecomment{sol}%
}%
\input test.tex

File test.tex:

\documentclass{article}
\usepackage{comment}
\providecommand\solutioninorexclude{%
  \excludecomment{sol}%
}%
\solutioninorexclude    

\begin{document}

This is the question.
\begin{sol}

This is the answer.
\end{sol}

\end{document}

Compiling test_sol.tex yields test_sol.pdf:

Compiling test.tex yields test.pdf:

A variation on this approach can be having test.tex create the file test_sol.tex for you automatically in case it does not exist:

When you save the example below as test.tex and compile it, you will get a file test.pdf which contains the text without solutions. You also get a file test_sol.tex. If you compile that, it will—via \input—import test.tex in a way where sol-environments are included. Thus you get a file test_sol.pdf which does also contain solutions:

\documentclass{article}
\usepackage{comment}
\providecommand\solutioninorexclude{%
  \excludecomment{sol}%
  \includecomment{solinputfile}%
}%
\solutioninorexclude    

\begin{solinputfile}
\begingroup
\makeatletter
\IfFileExists{\jobname\string_sol.tex}{%
  \@latex@warning@no@line{File \jobname\string_sol.tex already exists. Not generating it}%
}{%
  \@latex@warning@no@line{Generating file \jobname\string_sol.tex}%
  \newwrite\solinputfile
  \immediate\openout\solinputfile\jobname\string_sol.tex\relax
  \immediate\write\solinputfile{%
    \string\newcommand\string\solutioninorexclude{\@percentchar^^J%
    \space\space\string\includecomment{sol}\@percentchar^^J%
    \space\space\string\excludecomment{solinputfile}\@percentchar^^J%
    }\@percentchar^^J%
    \string\input\space\jobname.tex%
  }%
  \immediate\closeout\solinputfile
}%
\endgroup
\end{solinputfile}

\begin{document}

This is the question.
\begin{sol}

This is the answer.
\end{sol}

\end{document}

Yet another approach could be using something like the docstrip package. The purpose of the docstrip package is copying files of tex-source-code with having comments removed. It provides means for conditional inclusion of code into the copies.

E.g. if you save the following example as test.tex and compile it, you don't get a .pdf file but you get two new text files.

%<*ignore>
\input docstrip
\nopreamble
\nopostamble
\askforoverwritetrue
\generate{\file{\jobname\string_sol.tex}{\from{\jobname.tex}{sol}}}
\generate{\file{\jobname\string_nosol.tex}{\from{\jobname.tex}{}}}
% Here you can do some \immediate\write18-calls for calling LaTeX or
% TeXify or latexmk for compiling \jobname_sol.tex and
%\jobname_nosol.tex.
% You need to have the \write18-feature enabled for this.
% Some people take enabling \write18 for a security issue.
\csname stop\endcsname
\bye
%</ignore>
\documentclass{article}
% This comment won't occur in the generated files.
% This comment won't occur in the generated files.
\begin{document}
This is the question.
%<*sol>
    
This is the answer.
%</sol>
\end{document}

One of these text files is named test_nosol.tex and its content is:

\documentclass{article}
\begin{document}
This is the question.
\end{document}

The other of these text files is named test_sol.tex and its content is:

\documentclass{article}
\begin{document}
This is the question.

This is the answer.
\end{document}

Tokenization stage

The general rule is that spaces after control words (\par, for instance) are ignored, while after control symbols (\!, for instance) are retained; spaces at the beginning of a line are ignored altogether. Consecutive spaces are transformed into one space token but two consecutive end-of-lines become a \par (this statement is not fully correct, but not too incorrect for the purposes of this answer).

After the tokenization stage

There is an obvious intermix between tokenization stage and subsequent processing. In what follows "space" will mean "space token" and I won't care about spaces that have already disappeared, such as those after a control word).

It's now important to know that spaces in the input don't always produce spacing in the output. To understand why, it's necessary to learn some theory.

TeX is always in one of three modes: horizontal, vertical or math.

_{(The above paragraph tells a lie, strictly speaking: there is a circumstance in which it's not in one of these modes, but it's irrelevant for the discussion.)}

Under normal circumstances spaces do not produce output in vertical and math mode (let's not discuss the very special settings that make them appear).

It's quite easy to tell when TeX enters math mode: as soon as it sees $ or $$ (which, in LaTeX parlance, are, respectively \( and all the display math environments, initiated by \[, \begin{equation}, \begin{align} and so on). It exits math mode, returning to the previous mode when it sees the closing $ or $$ (with similar remarks as before for LaTeX).

Roughly speaking, TeX is in vertical mode at the start of a job or after a \par or when it's beginning a \vbox or \vtop or \vcenter; these are started, in LaTeX, by \parbox and \begin{minipage}. However, spaces in vertical and math mode are not suppressed: they are there, but produce no output. This is a cause for some misunderstandings. TeX starts horizontal mode when it sees a character to be typeset, \noindent, \indent or some other commands, notably \leavevmode (this is not an exhaustive list) or when it's starting an \hbox (for LaTeX it's \mbox, \makebox, \fbox, \colorbox, ... or the lrbox environment). In horizontal mode every space that's not absorbed by other rules (see later) produces output.

When TeX is absorbing the preamble of a LaTeX document it is in vertical mode. But a definition such as
```
\newcommand{\foo}{
  bar
}
```
will produce spaces in the output: the above is equivalent to
```
\newcommand{\foo}{ bar }
```
If \foo is seen at the beginning of a paragraph, the first space will not produce output (TeX is still in vertical mode), but the second will, as the b will trigger horizontal mode. Conversely
```
\newcommand{\baz}[1]{\parbox{10cm}{
  #1
}}
```
won't show spurious spaces. The first one, before #1 does nothing because it's seen in vertical mode; the final one, after #1 is suppressed because of the final implicit \par that ends the \parbox.
A definition such as
```
\newcommand{\myop}{
  \overset{t }{=}
}
```
will not need % to protect end-of-lines (translated into spaces), because it will be used in math mode (or will give an error anyway).

The most important (but easy) rule that should be considered is that tokens in the body of a definition are simply stored and not executed (they can be expanded in a \edef or \xdef, but still not executed). The execution is performed (after expansion) when the defined macro is used. The execution of a space token in vertical or math mode does nothing, in horizontal mode it produces a spacing in the output.

Numbers and dimensions

There is a place where space tokens have a peculiar behavior. When TeX is looking for a number or a dimension in order to perform an assignment or when expanding \number and \romannumeral, it expands tokens until an unexpandable token appears or a space token is found. In this case, the space is swallowed as part of the process.

This is one aspect to be kept in mind when writing macros. Let's see an example: we want to make a "monthly to-do list". Just a \parbox with twelve lines labelled by year and month; a loop seems the best approach, with the year given as argument:

\documentclass{article}
\newcount\monthlycount
\newcommand{\monthlytodo}[1]{\par%
  \fbox{%
    \parbox{10cm}{%
      \monthlycount=1%
      \loop\ifnum\monthlycount<13%
        #1--\number\monthlycount\hrulefill\par%
        \advance\monthlycount by 1%
      \repeat%
    }%
  }%
}
\begin{document}
\monthlytodo{2013}
\end{document}

Try it; this will surprise you with

! TeX capacity exceeded, sorry [main memory size=3000000].

Oh, boy! We've made sure that no spurious spaces were inserted by our macro! Why is TeX betraying us? Simple: the input can be written equivalently as

\loop\ifnum\monthlycount<13#1--\number\monthlycount

and #1 is replaced by 2013. So our loop checks whether the current value of \monthlycount is less than 132013 and stores tokens for the \parbox until TeX runs out of memory.

Let's try an amended version:

\newcommand{\monthlytodo}[1]{\par
  \fbox{%
    \parbox{10cm}{
      \monthlycount=1
      \loop\ifnum\monthlycount<13
        #1--\number\monthlycount\hrulefill\par
        \advance\monthlycount by 1
      \repeat
    }%
  }%
}

Look, ma! No spurious spaces!

enter image description here

Exercise 1 Why some lines end with % and other lines don't? We now know that % is harmful after 13 (and also after the 1 in the preceding line).

Technicality: space tokens are looked for but then swallowed also after keywords (such as by in the example and the unit names mm, pt and so on). There are also a few other places, but this answer is already too long. I'll show only how some of the problems can arise also when using LaTeX functions in this context:

\newcounter{monthlycount}
\newcommand{\monthlytodo}[1]{\par
  \fbox{%
    \parbox{10cm}{
      \setcounter{monthlycount}{1}
      \loop\ifnum\value{monthlycount}<13
        #1--\arabic{monthlycount}\hrulefill\par
        \stepcounter{monthlycount}
      \repeat
    }%
  }%
}

Exercise 2 Why isn't % necessary in lines 4–9 of the code above?

Best Answer

Related Solutions

macros – Best Macros for Common Abbreviations in LaTeX

LaTeX Macros – When is it Harmful to Add Percent Character at End of Lines in a \newcommand?

Tokenization stage

After the tokenization stage

Numbers and dimensions

Related Question