% Pandoc % John MacFarlane % December 29, 2006 Pandoc is a [Haskell] library for converting from one markup format to another, and a command-line tool that uses this library. It can read [markdown] and (subsets of) [reStructuredText], [HTML], and [LaTeX], and it can write [markdown], [reStructuredText], [HTML], [LaTeX], [RTF], [DocBook XML], and [S5] HTML slide shows. Pandoc's version of markdown contains some enhancements, like footnotes and embedded LaTeX. In contrast to existing tools for converting markdown to HTML, which use regex substitutions, Pandoc has a modular design: it consists of a set of readers, which parse text in a given format and produce a native representation of the document, and a set of writers, which convert this native representation into a target format. Thus, adding an input or output format requires only adding a reader or writer. [markdown]: http://daringfireball.net/projects/markdown/ [reStructuredText]: http://docutils.sourceforge.net/docs/ref/rst/introduction.html [S5]: http://meyerweb.com/eric/tools/s5/ [HTML]: http://www.w3.org/TR/html40/ [LaTeX]: http://www.latex-project.org/ [RTF]: http://en.wikipedia.org/wiki/Rich_Text_Format [DocBook XML]: http://www.docbook.org/ [Haskell]: http://www.haskell.org/ (c) 2006 John MacFarlane (jgm at berkeley dot edu). Released under the [GPL], version 2 or greater. This software carries no warranty of any kind. (See COPYRIGHT for full copyright and warranty notices.) Recai Oktaş (roktas at debian dot org) deserves credit for the build system, the debian package, and the robust wrapper scripts. [GPL]: http://www.gnu.org/copyleft/gpl.html "GNU General Public License" Requirements ============ The `pandoc` program itself does not depend on any external libraries or programs. The wrapper script `html2markdown` requires - `pandoc` (which must be in the PATH) - a POSIX-compliant shell (installed by default on all linux and unix systems, including Mac OS X, and in [Cygwin] for Windows), - `HTML Tidy` - `iconv` (for character encoding conversion). (If `iconv` is absent, `html2markdown` will still work, but it will treat everything as UTF-8.) The wrapper script `markdown2pdf` requires - `pandoc` (which must be in the PATH) - a POSIX-compliant shell - `pdflatex`, which should be part of any [LaTeX] distribution - the [unicode] and [fancyvrb] LaTeX packages, which are included in many LaTeX distributions.[^1] If your installation of LaTeX does not include these packages, you will get an error (complaining about missing `ucs.sty` or `fancyvrb.sty`) when you try to compile a LaTeX file produced by Pandoc, or when you use the `markdown2pdf` script (described below). If this happens, install the [unicode] and [fancyvrb] packages package from [CTAN]. (Get the zip file from CTAN and unpack it into `~/texmf/tex/latex/`. You may also need to run `mktexlsr` or `texhash` before the files can be found by TeX.) The wrapper script `hsmarkdown` requires only a POSIX-compliant shell. [Cygwin]: http://www.cygwin.com/ [HTML Tidy]: http://tidy.sourceforge.net/ [`iconv`]: http://www.gnu.org/software/libiconv/ [CTAN]: http://www.ctan.org "Comprehensive TeX Archive Network" [unicode]: http://www.ctan.org/tex-archive/macros/latex/contrib/unicode/ [fancyvrb]: http://www.ctan.org/tex-archive/macros/latex/contrib/fancyvrb/ [^1]: The [unicode] package allows LaTeX to process UTF-8 characters. [fancyvrb] allows code blocks and verbatim text to be used within footnotes. Using Pandoc ============ If you run `pandoc` without arguments, it will accept input from STDIN. If you run it with file names as arguments, it will take input from those files. By default, `pandoc` writes its output to STDOUT. If you want to write to a file, use the `-o` option: pandoc -o hello.html hello.txt Note that you can specify multiple input files on the command line. `pandoc` will concatenate them all (with blank lines between them) before parsing: pandoc -s chapter1.txt chapter2.txt references.txt > book.html (The `-s` option here tells `pandoc` to produce a standalone HTML file, with a proper header, rather than a fragment. For more details on this and many other command-line options, see below.) The format of the input and output can be specified explicitly using command-line options. The input format can be specified using the `-r/--read` or `-f/--from` options, the output format using the `-w/--write` or `-t/--to` options. Thus, to convert `hello.txt` from markdown to LaTeX, you could type: pandoc -f markdown -t latex hello.txt To convert `hello.html` from html to markdown: pandoc -f html -t markdown hello.html Supported output formats include `markdown`, `latex`, `html`, `rtf` (rich text format), `rst` (reStructuredText), `docbook` (DocBook XML), and `s5` (which produces an HTML file that acts like powerpoint). Supported input formats include `markdown`, `html`, `latex`, and `rst`. Note that the `rst` reader only parses a subset of reStructuredText syntax. For example, it doesn't handle tables, definition lists, option lists, or footnotes. It handles only the constructs expressible in unextended markdown. But for simple documents it should be adequate. The `latex` and `html` readers are also limited in what they can do. Because the `html` reader is picky about the HTML it parses, it is recommended that you pipe HTML through [HTML Tidy] before sending it to `pandoc`, or use the `html2markdown` script described below. If you don't specify a reader or writer explicitly, `pandoc` will try to determine the input and output format from the extensions of the input and output filenames. Thus, for example, pandoc -o hello.tex hello.txt will convert `hello.txt` from markdown to LaTeX. If no output file is specified (so that output goes to STDOUT), or if the output file's extension is unknown, the output format will default to HTML. If no input file is specified (so that input comes from STDIN), or if the input files' extensions are unknown, the input format will be assumed to be markdown unless explicitly specified. Character encodings ------------------- Unfortunately, due to limitations in GHC, `pandoc` does not automatically detect the system's local character encoding. Hence, all input and output is assumed to be in the UTF-8 encoding. If your local character encoding is not UTF-8 and you use accented or foreign characters, you should pipe the input and output through [`iconv`]. For example, iconv -t utf-8 source.txt | pandoc | iconv -f utf-8 > output.html will convert `source.txt` from the local encoding to UTF-8, then convert it to HTML, then convert back to the local encoding, putting the output in `output.html`. The shell scripts (described below) automatically convert the input from the local encoding to UTF-8 before running them through `pandoc`, then convert the output back to the local encoding. `markdown2pdf`, `html2markdown`, and `hsmarkdown` ================================================= Three shell scripts, `markdown2pdf`, `html2markdown`, and `hsmarkdown`, are included in the standard Pandoc installation. (They are not included in the Windows binary package, as they require a POSIX shell, but they may be used in Windows under Cygwin.) 1. `markdown2pdf` produces a PDF file from markdown-formatted text, using `pandoc` and `pdflatex`. The default behavior of `markdown2pdf` is to create a file with the same base name as the first argument and the extension `pdf`; thus, for example, markdown2pdf sample.txt endnotes.txt will produce `sample.pdf`. (If `sample.pdf` exists already, it will be backed up before being overwritten.) An output file name can be specified explicitly using the `-o` option: markdown2pdf -o "My Book.pdf" chap1.txt chap2.txt chap3.txt If no input file is specified, input will be taken from STDIN. All of `pandoc`'s options will work with `markdown2pdf` as well. 2. `html2markdown` grabs a web page from a file or URL and converts it to markdown-formatted text, using `tidy` and `pandoc`. All of `pandoc`'s options will work with `html2markdown` as well. In addition, the following special options may be used. The special options must be separated from the `html2markdown` command and any regular Pandoc options by the delimiter `--`: html2markdown -o out.txt -- -e latin1 -g curl google.com The `-e` or `--encoding` option specifies the character encoding of the HTML input. If this option is not specified, and input is not from STDIN, `html2markdown` will attempt to determine the page's character encoding from the "Content-type" meta tag. If this is not present, UTF-8 is assumed. The `-g` or `--grabber` option specifies the command to be used to fetch the contents of a URL: html2markdown -g 'curl --user foo:bar' www.mysite.com If this option is not specified, `html2markdown` searches for an available program (`wget`, `curl`, or a text-mode browser) to fetch the contents of a URL. 3. `hsmarkdown` is designed to be used as a drop-in replacement for `Markdown.pl`. It forces `pandoc` to convert from markdown to HTML, and to use the `--strict` flag for maximal compliance with official markdown syntax. (All of Pandoc's syntax extensions and variants, described below, are disabled.) No other command-line options are allowed. (In fact, options will be interpreted as filenames.) Command-line options ==================== Various command-line options can be used to customize the output. For further documentation, see the `pandoc(1)` man page. `-f`, `--from`, `-r`, or `--read` can be used to specify the input format -- the format Pandoc will be converting *from*. Available formats are `native`, `markdown`, `rst`, `html`, and `latex`. `-t`, `--to`, `-w`, or `--write` can be used to specify the output format -- the format Pandoc will be converting *to*. Available formats are `native`, `html`, `s5`, `docbook`, `latex`, `markdown`, `rst`, and `rtf`. `-s` or `--standalone` indicates that a standalone document is to be produced (with appropriate headers and footers), rather than a fragment. `-o` or `--output` specifies the name of the output file. If this option is not specified, or if its argument is `-`, output will be sent to STDOUT. `-p` or `--preserve-tabs` causes tabs in the source text to be preserved, rather than converted to spaces (the default). `--tabstop` allows the user to set the tab stop (which defaults to 4). `--strict` specifies that strict markdown syntax is to be used, without pandoc's usual extensions and variants (described below). `-R` or `--parse-raw` causes the HTML and LaTeX readers to parse HTML codes and LaTeX environments that it can't translate as raw HTML or LaTeX. Raw HTML can be printed in markdown, reStructuredText, HTML, and S5 output; raw LaTeX can be printed in markdown, reStructuredText, and LaTeX output. The default is for the readers to omit untranslatable HTML codes and LaTeX environments. (The LaTeX reader does pass through untranslatable LaTeX commands, even if `-R` is not specified.) `-C` or `--custom-header` can be used to specify a custom document header. To see the headers used by default, use the `-D` option: for example, `pandoc -D html` prints the default HTML header. `-c` or `--css` allows the user to specify a custom stylesheet that will be linked to in HTML and S5 output. `-H` or `--include-in-header` specifies a file to be included (verbatim) at the end of the document header. This can be used, for example, to include special CSS or javascript in HTML documents. `-B` or `--include-before-body` specifies a file to be included (verbatim) at the beginning of the document body (after the `` tag in HTML, or the `\begin{document}` command in LaTeX). This can be used to include navigation bars or banners in HTML documents. `-A` or `--include-after-body` specifies a file to be included (verbatim) at the end of the docment body (before the `` tag in HTML, or the `\end{document}` command in LaTeX). `-T` or `--title-prefix` specifies a string to be included as a prefix at the beginning of the title that appears in the HTML header (but not in the title as it appears at the beginning of the HTML body). (See below on Titles.) `-S` or `--smart` causes `pandoc` to produce typographically correct output, along the lines of John Gruber's [Smartypants]. Straight quotes are converted to curly quotes, `---` to dashes, and `...` to ellipses. (Note: This option is only significant when the input format is `markdown`. It is selected automatically when the output format is `latex`.) [Smartypants]: http://daringfireball.net/projects/smartypants/ `-m` or `--asciimathml` will cause LaTeX formulas (between $ signs) in HTML or S5 to display as formulas rather than as code. The trick will not work in all browsers, but it works in Firefox. Peter Jipsen's [ASCIIMathML] script is used to do the magic. [ASCIIMathML]: http://www1.chapman.edu/~jipsen/mathml/asciimath.html `-i` or `--incremental` causes all lists in S5 output to be displayed incrementally by default (one item at a time). The normal default is for lists to be displayed all at once. `-N` or `--number-sections` causes sections to be numbered in LaTeX output. By default, sections are not numbered. `--dump-args` is intended to make it easier to create wrapper scripts that use Pandoc. It causes Pandoc to dump information about the arguments with which it was called to STDOUT, then exit. The first line printed is the name of the output file specified using the `-o` or `--output` option, or `-` if output would go to STDOUT. The remaining lines, if any, list command-line arguments. These will include the names of input files and any special options passed after ` -- ` on the command line. So, for example, pandoc --dump-args -o foo.html -s foo.txt appendix.txt -- -e latin1 will cause the following to be printed to STDOUT: foo.html foo.txt appendix.txt -e latin1 `--ignore-args` causes Pandoc to ignore all command-line arguments. Regular Pandoc options are not ignored. Thus, for example, pandoc --ignore-args -o foo.html -s foo.txt -- -e latin1 is equivalent to pandoc -o foo.html -s `-v` or `--version` prints the version number to STDERR. `-h` or `--help` prints a usage message to STDERR. Pandoc's markdown vs. standard markdown ======================================= In parsing markdown, Pandoc departs from and extends [standard markdown] in a few respects. (To run Pandoc on the official markdown test suite, type `make test-markdown`.) Except where noted, these differences can be suppressed by specifying the `--strict` command-line option or by using the `hsmarkdown` wrapper. [standard markdown]: http://daringfireball.net/projects/markdown/syntax "Markdown syntax description" Backslash escapes ----------------- Except inside a code block or inline code, any punctuation or space character preceded by a backslash will be treated literally, even if it would normally indicate formatting. Thus, for example, if one writes *\*hello\** one will get *hello* instead of hello This rule is easier to remember than standard markdown's rule, which allows only the following characters to be backslash-escaped: \`*_{}[]()>#+-.! Lists ----- Pandoc behaves differently from standard markdown on some "edge cases" involving lists. Consider this source: 1. First 2. Second: - Fee - Fie - Foe 3. Third Pandoc transforms this into a "compact list" (with no `

` tags around "First", "Second", or "Third"), while markdown puts `

` tags around "Second" and "Third" (but not "First"), because of the blank space around "Third". Pandoc follows a simple rule: if the text is followed by a blank line, it is treated as a paragraph. Since "Second" is followed by a list, and not a blank line, it isn't treated as a paragraph. The fact that the list is followed by a blank line is irrelevant. (Note: Pandoc works this way even when the `--strict` option is specified. This behavior is consistent with the official markdown syntax description, even though it is different from that of `Markdown.pl`.) Unlike standard markdown, Pandoc allows ordered list items to be marked with single letters, instead of numbers. So, for example, this source yields a nested ordered list: 1. First 2. Second a. Fee b. Fie 3. Third Pandoc also extends standard markdown in allowing list item markers to be terminated by ')': 1) First 2) Second A) Fee B) Fie 3) Third Note that Pandoc pays no attention to the *type* of ordered list item marker used. Thus, the following is treated just the same as the example above: A) First 1. Second 2. Fee B) Fie C) Third Reference links --------------- Pandoc allows implicit reference links with just a single set of brackets. So, the following links are equivalent: 1. Here's my [link] 2. Here's my [link][] [link]: linky.com (Note: Pandoc works this way even if `--strict` is specified, because `Markdown.pl` 1.0.2b7 allows single-bracket links.) Footnotes --------- Pandoc's markdown allows footnotes, using the following syntax: Here is a footnote reference,[^1] and another.[^longnote] [^1]: Here is the footnote. It can go anywhere in the document, except in embedded contexts like block quotes or lists. [^longnote]: Here's the other note. This one contains multiple blocks. Subsequent paragraphs are indented to show that they belong to the previous footnote. { some.code } The whole paragraph can be indented, or just the first line. In this way, multi-paragraph footnotes work just like multi-paragraph list items in markdown. This paragraph won't be part of the note. The identifiers in footnote references may not contain spaces, tabs, or newlines. These identifiers are used only to correlate the footnote reference with the note itself; in the output, footnotes will be numbered sequentially. Inline footnotes are also allowed (though, unlike regular notes, they cannot contain multiple paragraphs). The syntax is as follows: Here is an inline note.^[Inlines notes are easier to write, since you don't have to pick an identifier and move down to type the note.] Inline and regular footnotes may be mixed freely. Embedded HTML ------------- Pandoc treats embedded HTML in markdown a bit differently than Markdown 1.0. While Markdown 1.0 leaves HTML blocks exactly as they are, Pandoc treats text between HTML tags as markdown. Thus, for example, Pandoc will turn
*one* [a link](http://google.com)
into
one a link
whereas `Markdown.pl` will preserve it as is. There is one exception to this rule: text between `` tags is not interpreted as markdown. This departure from standard markdown should make it easier to mix markdown with HTML block elements. For example, one can surround a block of markdown text with `

` tags without preventing it from being interpreted as markdown. Title blocks ------------ If the file begins with a title block % title % author(s) (separated by commas) % date it will be parsed as bibliographic information, not regular text. (It will be used, for example, in the title of standalone LaTeX or HTML output.) The block may contain just a title, a title and an author, or all three lines. Each must begin with a % and fit on one line. The title may contain standard inline formatting. If you want to include an author but no title, or a title and a date but no author, you need a blank line: % My title % % June 15, 2006 Titles will be written only when the `--standalone` (`-s`) option is chosen. In HTML output, titles will appear twice: once in the document head -- this is the title that will appear at the top of the window in a browser -- and once at the beginning of the document body. The title in the document head can have an optional prefix attached (`--title-prefix` or `-T` option). The title in the body appears as an H1 element with class "title", so it can be suppressed or reformatted with CSS. If a title prefix is specified with `-T` and no title block appears in the document, the title prefix will be used by itself as the HTML title. Box-style blockquotes --------------------- Pandoc supports emacs-style boxquote block quotes, in addition to standard markdown (email-style) boxquotes: ,---- | They look like this. `---- Blank lines before headers and blockquotes ------------------------------------------ Standard markdown syntax does not require a blank line before a header or blockquote. Pandoc does require this (except, of course, at the beginning of the document). The reason for the requirement is that it is all too easy for a `>` or `#` to end up at the beginning of a line by accident (perhaps through line wrapping). Consider, for example: I like several of their flavors of ice cream: #22, for example, and #5. Inline LaTeX ------------ Anything between two $ characters will be parsed as LaTeX math. The opening $ must have a character immediately to its right, while the closing $ must have a character immediately to its left. Thus, `$20,000 and $30,000` won't parse as math. The $ character can be escaped with a backslash if needed. If you pass the `-m` (`--asciimathml`) option to `pandoc`, it will include the [ASCIIMathML] script in the resulting HTML. This will cause LaTeX math to be displayed as formulas in better browsers. [ASCIIMathML]: http://www1.chapman.edu/~jipsen/asciimath.html Inline LaTeX commands will also be preserved and passed unchanged to the LaTeX writer. Thus, for example, you can use LaTeX to include BibTeX citations: This result was proved in \cite{jones.1967}. You can also use LaTeX environments. For example, \begin{tabular}{|l|l|}\hline Age & Frequency \\ \hline 18--25 & 15 \\ 26--35 & 33 \\ 36--45 & 22 \\ \hline \end{tabular} Note, however, that material between the begin and end tags will be interpreted as raw LaTeX, not as markdown. Custom headers ============== When run with the "standalone" option (`-s`), `pandoc` creates a standalone file, complete with an appropriate header. To see the default headers used for html and latex, use the following commands: pandoc -D html pandoc -D latex If you want to use a different header, just create a file containing it and specify it on the command line as follows: pandoc --header=MyHeaderFile Producing S5 with Pandoc ======================== Producing an [S5] web-based slide show with Pandoc is easy. A title page is constructed automatically from the document's title block (see above). Each section (with a level-one header) produces a single slide. (Note that if the section is too big, the slide will not fit on the page; S5 is not smart enough to produce multiple pages.) Here's the markdown source for a simple slide show, `eating.txt`: % Eating Habits % John Doe % March 22, 2005 # In the morning - Eat eggs - Drink coffee # In the evening - Eat spaghetti - Drink wine To produce the slide show, simply type pandoc -w s5 -s eating.txt > eating.html and open up `eating.html` in a browser. The HTML file embeds all the required javascript and CSS, so no other files are necessary. Note that by default, the S5 writer produces lists that display "all at once." If you want your lists to display incrementally (one item at a time), use the `-i` option. If you want a particular list to depart from the default (that is, to display incrementally without the `-i` option and all at once with the `-i` option), put it in a block quote: > - Eat spaghetti > - Drink wine In this way incremental and nonincremental lists can be mixed in a single document.