How do I print out dates in YYYY-MMM-DD format?

Question

Is there an easy way to print out dates in the format of 2014-Jan-15. Being in North America, Canada not the USA, there are too many date formats in use. To remove any chance of confusion the client would like to use YYYY-MMM-DD.

I can do my program creating the latex PDF is running on debin Linux and not Windows.

Answer 1

Use the datetime package:

\documentclass{article}

\makeatletter
\newcommand\FormatDate[3]{%
  #1-\shortmonthname[#2]-\two@digits{#3}}
\makeatother

\usepackage{datetime}
\newdateformat{gregdate}{\FormatDate{\THEYEAR}{\THEMONTH}{\THEDAY}}

\newcommand\Demonstrate[3]{%
  Date #1-#2-#3 formats as \FormatDate{#1}{#2}{#3}.\par}
\setlength\parindent{0pt}

\begin{document}
\Demonstrate{2015}{01}{01}
\Demonstrate{2015}{02}{02}
\Demonstrate{2015}{03}{03}
\Demonstrate{2015}{04}{04}
\Demonstrate{2015}{05}{05}
\Demonstrate{2015}{06}{06}
\Demonstrate{2015}{07}{07}
\Demonstrate{2015}{08}{08}
\Demonstrate{2015}{09}{09}
\Demonstrate{2015}{10}{10}
Today is {\gregdate\today}.
\end{document}

---

If you wish to rename months, you can redefine \shormonthnameenglish to suit your needs. (You can patch other macros as used by babel, if necessary; see dt-austrian.def, for example.)

\renewcommand*{\shortmonthnameenglish}[1][\month]{%
  \@orgargctr=#1\relax
  \ifcase\@orgargctr
  \PackageError{datetime}{Invalid Month number \the\@orgargctr}{Month
  numbers should go from 1 (jan) to 12 (dec)}%
  \or Jan%
  \or Feb%
  \or Mar%
  \or Apr%
  \or May%
  \or Jun%
  \or Jul%
  \or Aug%
  \or Sept%
  \or Oct%
  \or Nov%
  \or Dec%
  \else%
  \PackageError{datetime}%
  {Invalid Month number \the\@orgargctr}%
  {Month numbers should go from 1 (jan) to 12 (dec)}%
\fi
}

Answer 2

Have a look at the isodate package:

\documentclass[english]{article}
\usepackage{babel}
\usepackage{isodate}

\begin{document}

\isodate \today

\end{document}

Answer 3

Taking a look at article.cls you find the definition of the macro \today. You could re-define that macro to suit your tastes and even define a new macro (e.g., \mydate) to print in the style you asked the date inserted in the usual format.

\documentclass{article}
\let\oldtoday\today
\def\today{%
  \number\year-\ifcase\month\or%
  Jan\or Feb\or Mar\or Apr\or May\or Jun\or%
  Jul\or Aug\or Sep\or Oct\or Nov\or Dec\fi%
  -\number\day%
}
\newcommand{\mydate}[3]{%
  \number#1-\ifcase#2\or%
  Jan\or Feb\or Mar\or Apr\or May\or Jun\or%
  Jul\or Aug\or Sep\or Oct\or Nov\or Dec\fi%
  -\number#3%
}
\begin{document}
\today{} vs. \mydate{2015}{01}{21}
\end{document}