[Tex/LaTex] the XeTeX equivalent of \pdfcreationdate

datetimexetex

I need the time to 1-second resolution.

datetime uses \pdfcreationdate for this, but only under pdf(La)TeX.

As a result under XeLaTeX, this:

\usepackage{datetime}
...
\newtimeformat{hhmmss}{\twodigit{\THEHOUR}\twodigit{\THEMINUTE}\twodigit{\THESECOND}}
\settimeformat{hhmmss}
\currenttime

always produces 00 as the last two digits, eg:

113600

Best Answer

There is no \pdfcreationdate command in XeTeX as in pdfTeX and LuaTeX. There is a technical reason, for this: the PDF file is produced by XeTeX in an asynchronous way, delivering the pages produced in xdv format to xdvipdfmx. In general, these files are kept in a temporary directory and the PDF is finally moved to the current directory at the end.

One could use the shell escape, checking the date of creation of the .log file, which is opened at the start of the job, but this would be system dependent.

Emulate \pdfcreationdate in XeTeX

We can use LuaTeX also from XeTeX (or XeLaTeX)! Create the following file creationdate.lua:

os.remove("creationdate.timestamp")
io.output("creationdate.timestamp"):write(os.date("\\edef\\tempa{\\string D:%Y%m%d%H%M%S}\n\\def\\tempb{%z}"))\end{filecontents*}

Then put the following code before loading datetime:

\ifdefined\pdfcreationdate\else
\begingroup
  \ifnum\shellescape=1
    \immediate\write18{texlua creationdate.lua}
    \input{creationdate.timestamp}
    \def\tempc#1#2#3#4#5{#1#2#3'#4#5'}
    \edef\tempb{\expandafter\tempc\tempb}
    \edef\x{\endgroup\def\noexpand\pdfcreationdate{\tempa\tempb}}\x
  \fi
\fi

The file creationdate.timestamp will be removed, if existent, and a new one created with the current time in it, in a format similar to that produced by \pdfcreationdate in pdfTeX. Then it will be read in; the time shown will be that of the execution of the script. However, any recent TeX distribution should have texlua (because it has luatex), so this should be as system independent as possible.

Actually, what's written in creationdate.timestamp is something like

\edef\tempa{\string D:20120122195802}
\def\tempb{+0100}

and then its contents is massaged a bit to get it into, essentially,

\def\pdfcreationdate{D:20120122195802+01'00'}

that's the format requested by datetime (the D must have category code 12, because such is the one produced by \pdfcreationdate in (pdf|Lua)TeX).

A complete example, to be run with --shell-escape, as always (otherwise \pdfcreationdate will not be defined and datetime will show seconds as "00"); the macros do nothing if \pdfcreationdate is already present (so using pdftex or luatex as engines).

\begin{filecontents*}{creationdate.lua}
os.remove("creationdate.timestamp")
io.output("creationdate.timestamp"):write(os.date("\\edef\\tempa\{\\string D:%Y%m%d%H%M%S\}\n\\def\\tempb\{%z\}"))
\end{filecontents*}
\documentclass{standalone}
\ifdefined\pdfcreationdate\else
\begingroup
  \ifnum\shellescape=1
    \immediate\write18{texlua creationdate.lua}
    \input{creationdate.timestamp}
    \def\tempc#1#2#3#4#5{#1#2#3'#4#5'}
    \edef\tempb{\expandafter\tempc\tempb}
    \edef\x{\endgroup\def\noexpand\pdfcreationdate{\tempa\tempb}}\x
  \fi
\fi

\usepackage{datetime}
\newtimeformat{hhmmss}{\twodigit{\THEHOUR}\twodigit{\THEMINUTE}\twodigit{\THESECOND}}
\settimeformat{hhmmss}
\begin{document}
\currenttime
\end{document}

An alternative way on Unix systems

Unfortunately, XeTeX doesn't sport the pdfTeX feature of \input|<command>, so an indirect way has to be taken, creating an auxiliary file to be read in.

  • Create a shell script creationdate.sh
    #! /bin/sh
    rm -f $1.timestamp
    date -r `stat -f '%m' -t '%s' $1.log` '+D:%Y%m%d%H%M%S+000000' > $1.timestamp
  • Give the file the executable bit
    chmod u+x creationdate.sh

  • Put the following in the file before loading datetime

    \usepackage{catchfile}
\ifdefined\pdfcreationdate\else
  \ifnum\shellescape=1
    \immediate\write18{./creationdate.sh \jobname}
    \CatchFileDef\pdfcreationdate{\jobname.timestamp}{\catcode`\D=12 }
  \fi
\fi

Then your commands will give the required result. Of course one must check that stat and date accept the required command line options.

XeLaTeX must be run with the -shell-escape command line option, of course. If it isn't, then the behavior will be as without \pdfcreationdate available, that is, the seconds will always be "00". If the file is processed with pdfLaTeX or LuaLaTeX, this definition of \pdfcreationdate will be ignored and datetime will be happy nonetheless, as those engines already have \pdfcreationdate.

On Windows a suitable batch script can be devised.

Update July 2016

With the new texosquery script, the code can be simplified:

\documentclass{standalone}
\usepackage{luatex85}

\ifdefined\pdfcreationdate\else
  \usepackage{texosquery}
  \TeXOSQueryNow{\pdfcreationdate}
  \edef\pdfcreationdate{\detokenize\expandafter{\pdfcreationdate}}
\fi

\usepackage{datetime}
\newtimeformat{hhmmss}{\twodigit{\THEHOUR}\twodigit{\THEMINUTE}\twodigit{\THESECOND}}
\settimeformat{hhmmss}
\begin{document}
\currenttime
\end{document}

I added luatex85 in case LuaLaTeX is used. In this way, -shell-escape is only needed for XeLaTeX. The \edef with \detokenize is necessary, because \TeXOSQueryNow returns the starting D with category code “letter” and the macros in datetime assume category code “other” instead.

Note: the Java application, at the moment, seems only to run with Java 1.7.0_52 or later, but I was successful in recompiling it on 1.7.0_45. It would be nice if the application was made usable also with previous versions of Java.

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