Do you know things about Linux for which no good free documentation is available and which would be useful to others? Even if you don't know the subject well, you can still write about it if you're eager, willing, and able to learn more about it. Can you write clearly using a word processor or editor? Do you want to help thousands of others and let them read what you write at no cost to them? Once you've written a document, are you willing to receive email suggestions from readers and selectively use this info for improving your HOWTO? Would you like to have your writings be available on hundreds of websites throughout the world? If you can answer yes to these, then you're encouraged to write something for the LDP. But be warned that it may take more time than you expected.
Copyright (c) 2001-3 by David S. Lawyer. You may freely copy and distribute (sell or give away) this document. You may create a derivative work and distribute it provided that you licnese it in the spirit of this license and give proper credits. The author would like to receive your comments, suggestions, and plans for any derivative work based on this.
Why did I write this when there is already an "LDP Authoring Guide"? Well, the LDP guide is a long and detailed work. If you want to get started quickly, you need something much simpler and shorter.
Thanks to Matt Welsh for his example.sgml file which I used as a major source of info for the example sections.
All HOWTOs and other LDP documents are copyright by the authors so the LDP doesn't have any special rights to your writing. We only accept documents that have a license which permits anyone to copy and distribute the document. We encourage authors to also allow modification in their license. This way, if the author stops maintaining a document, someone else can do so. For more details see our Manifesto.
If you are not sure what to write about, take look at some of LDP's documents, including the ones in "unmaintained. You should find ones that need rewriting. Also you may find topics that you are interested in that are not adequately covered by existing documentation. If you find something already written that seems to need a lot of improvement, try to contact the author.
Our HOWTOs are released in various formats: Plain Text, HTML, PostScript, and PDF. Instead of having to write the same HOWTO in all of these formats, just one HOWTO is written in a source format which gets converted by computer into all of the others.
To get an idea of what a source format looks like, take a look at the source file of a webpage (if you haven't already). You will see all sorts of words in <angle brackets>. These are called tags. These webpages (tags and all) are in html: Hypertext Markup Language. The LDP uses something like this for its documents.
The languages LDP uses meet the requirements of the Standard Generalized Markup Language or SGML for short. The LDP now uses the following two flavors of sgml: LinuxDoc and DocBook. Originally it only used LinuxDoc (which was sometimes incorrectly just called sgml). Interestingly, it turns out that html is still another flavor of sgml. Some people have gone from the DocBook flavor of sgml to the DocBook flavor of the XML standard.
This mini-HOWTO is all about using the simple LinuxDoc flavor of sgml. You may call it "LinuxDoc markup". It can be machine converted to html, plain text, postscript, pdf, and DocBook. It's a lot easier than html or DocBook and you don't need a special editor for it as it's easy to type in the tags (or use macros for them).
One way to do this is to go to the LDP site http://www.linuxdoc.org click on HOWTOs and then compare the sources of the same HOWTO in the two formats: LinuxDoc and DocBook. The DocBook tags are often longer than the equivalent LinuxDoc tags and there are sometimes more of them needed to do the same task. DocBook uses <para> and </para> tags to enclose each paragraph while LinuxDoc uses only a blank line to separate paragraphs (no tags needed). For some examples see Comparison of DocBook to LinuxDoc
So there's much more to type with DocBook if you're typing in tags manually. But DocBook has all sorts of tags that don't exist in LinuxDoc so it's more advanced. Just using a subset of DocBook doesn't help as you can see from the above examples partly because DocBook nests tags (uses more tags to do the same thing). With a more and longer tags the DocBook source becomes harder to read unless you use an editor that hides them. But hiding them has it's drawbacks since it's nice to see what tags you've used.
Still, the number of people who use DocBook greatly exceeds the number using LinuxDoc. But if you do decide to migrate to DocBook there's a program by Reuben Thomas (ld2db) which can help make the conversion. It's not 100% perfect and you may have to do some manual editing. The LDP also automatically converts a LinuxDoc HOWTO to DocBook after you submit it.
LinuxDoc is a lot easier to learn than DocBook. But most of what you learn about LinuxDoc would also be useful for DocBook. So if you eventually decide to go for DocBook, most of the effort spent on learning LinuxDoc will not be wasted.
One way to learn it is by examples. I've written 3 example files ranging from easy to intermediate. The contents of these files have been copied into this Howto. To turn them into individual files you may cut them out (start with the first tag) and write them to files. Then you could try turning one into text by using say "sgml2txt -f example2.sgml" to see what it looks like. Make sure the file names end in .sgml.
If you want to look at some real examples you can just go to an LDP mirror site, find the HOWTOs and select LinuxDoc SGML. Or go to the main site directly: http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/sgml Now for the first simple example.
<!doctype linuxdoc system> <article> <title>First Example (example1) <author>David S.Lawyer <sect> Introduction <p> This is a very simple example of "source" for the LinuxDoc text formatting system. This paragraph begins with a paragraph tag (a "p" enclosed in angle brackets). Notice that there are other tags, also enclosed in angle brackets. If you don't see any tags, then you are reading a converted file so find the source file: example1.sgml (which contains the tags). This is the next paragraph. Note that it is separated from the above paragraph by just a blank line. Thus it needs no "p" tag in front of it. The "p" tag is only needed for the first paragraph of a section (just after the sect-tag). The file suffix: sgml stands for Standard Generalized Markup Language. You are now reading the LinuxDoc flavor of sgml as specified in the very first line of this file. <sect> Tags <p> Tags are words inside angle brackets. The "sect" tag above marks the start of a new section of this example document. "Introduction" was the first section and you are now reading the second section titled "Tags". If this were a long document (like a book), a section would correspond to a chapter. Note that there are "article", "title" and "author" tags at the start of this article. At the end of this article is an "/article" tag marking the end of this article. Thus there is a pair of "article" tags, the first being the start tag and the second being the end tag. Thus this entire article is enclosed in "article" tags. In later examples you'll see that there are other tags that come in pairs like this. They affect whatever is between the pairs (start tag and end tag). Any tag name which has "/" just before it is an "end tag". When this source code is converted to another format (such as plain text using the program sgml2txt) the tags are removed. Tags only help the sgml2txt program make the conversion. There are more tags to learn. So once you understand this example1, please go on to the next example: example2. You don't need to actually memorize the tags, as they will be repeated (but with little or no explanation) in later examples. </article>
<!-- This is a comment. It's ignored when this source file gets converted to other formats. --> <!-- The tag below says that this file is in LinuxDoc format --> <!doctype linuxdoc system> <article> <title>Second Example (example2) <author>David S. Lawyer <date>v1.0, July 2000 <abstract> This is the abstract. This document is the second example of using the Linuxdoc-SGML flavor of sgml. It's more complex than the first example (example1.sgml) but simpler than the third example (example3.sgml). After you digest this you'll be able to write a simple HOWTO using LinuxDoc. End of the abstract. </abstract> <!-- The "toc" = Table of Contents. It will be created here. --> <toc> <!-- Begin the main part of the article (or document) here. The part above this is sort of a long header. --> <sect>This Second Example (example2.sgml) <p>Unless you're familiar with markup languages, you should first read example1.sgml. You may want to run these example files thru a translator such as sgml2txt to convert them to text and notice how the result looks different than this "source" document with all its tags. <sect>Article Layout <sect1> Document Body <p> After the header comes the body of the document, consisting of nested sections marked by sect-tags. Subsections are marked by sect1-tags. Since this is the first subsection within the 2nd main section, it's becomes section 2.1. Within a subsection marked by sect1 there may be sub-subsections like sect2. There are even tags like sect3, sect4, etc., but you are unlikely to need them. Note the the real tags must be encosed in angle brackets < and >. If I had put these brakets <sect2> This is a sub-sub-section <p> It's 2.1.1. Note that a "p" tag may be on a line by itself. This doesn't change a thing in the resulting documents. <sect1>Document Header <p> One way to create a header part is just to copy one from another .sgml file. Then replace everything except the tags with the correct info for your document. This is like using a "template". <sect> More Features in example3 <p> With the tags in this example2 you can write a simple short document a few pages long. But for longer documents or for other important features such as putting links into documents, you need to study the next example: example3. It will also show you how to create lists and fonts. </article>
<!doctype linuxdoc system> <!-- Note the mailto: after my name. This allows the reader of html format to click on my email address to send me email --> <article> <title>Third Example (example3) <author>David S. Lawyer <url url="mailto:email@example.com"> <date>v1.0, July 2000 <abstract> This document is the third example of using the LinuxDoc flavor of sgml. It's more complex than the second example. </abstract> <!-- Comment: toc = Table of Contents --> <toc> <sect> Fonts <p> While they will not show up in a plain text output, they will work for other conversions. <bf>boldface font</bf> <em>emphasis font</em> <sf>sans serif</sf> <sl>slanted font</sl> <tt>typewriter font</tt> <it>italics font</it> There's another way to get these same fonts by enclosing the text in slashes like this: <bf/boldface font/ <em/emphasis font/ <sf/sans serif/ <sl/slanted font/ <tt/typewriter font/ <it/italics font/ Note that DocBook doesn't have font tags so it may be best not to use fonts if you plan to convert to DocBook. <sect> Links <label id="links_"> <p> You may create links (something that html browsers may click on to go somewhere else). They might just go to another part of this document (cross-references) such as to the "label" above, or they could go to a website on the Internet. <sect1> Cross-References <p> If you click on <ref id="links_" name="Links"> you will be taken to the start of the "Links" section above (which is labeled links_). The label id may be any word you choose but it's a good idea to avoid common words so that you can search for unique labels using your editor. That's why I use links_ (with the underline). The name of this link will be shown (in html format) as the name to click on. This name (Links) will also be present in the text rendition. <sect1> URL Links <p> If you click on <url url="http://www.tldp.org"> you will get to the Linux Documentation Project website. The next link adds a name which people will click on: <url url="http://www.linuxdoc.org" name="Linux Documentation Project">. Using this second method, you may not even need to explain where the link leads to since it's obvious by the name. <sect> Prohibited Characters <p> Any word you type between angle brackets will be interpreted as a tag. But what if you want to display a tag in a document? For this you use a code word for the angle characters. You may use < for < and > for >. lt = Less Than, gt = Greater Than. For example, here's a p-tag: <p>. Of course it doesn't actually start any paragraph, but it will appear in the converted document as <p>. These codes all start with an & character. The ; after the lt is to separate it. It's not needed if there is a space after it. For example: 3 < 4. Actually, if you knew that its OK to use an unpaired > then you could have written <p> as <p>. This will not be mistakenly recognized as a tag since there is no opening <. Actually 3 < 4 works fine too. There are other characters that you can't put into the document text directly. For & in an AT modem command use: AT&. If other characters cause you trouble (they seldom will) see <ref id="ch_codes" name="Character Codes (macros)"> or the "guide" that comes with linuxdoc-tools or sgml-tools. <sect> Verbatim, Code & Newline <sect1> Verbatim <p> If you want to insure that it will look exactly like you typed it after it's converted to other formats, use verbatim (verb). This is useful for creating tables, etc. But some things still get recognized as markup even though they are between verbatim tags. This includes the macros starting with & and end tags with /. <tscreen><verb> % sgml2txt -f example.sgml </verb></tscreen> The "tscreen" sets the font to typewriter and indents it nicely. <sect1> Code <p> This encloses computer code between two dashed lines. <tscreen><code> Put computer source code here </code></tscreen> <sect1> Newline <p> To force a newline use <newline> This sentence always starts at the left margin. <sect>Lists <p> This puts items into a list with a bullet at the start of each item. They start with the "itemize" tag. <itemize> <item> This is the first item in a list. <item> This is the second item <itemize> <item> Multiple levels (nesting) are supported. <item> The second item in this sublist </itemize> <enum> <item> Enumerated lists using <tt/enum/ also work. <item> This is item number 2 </enum> <item> The final item in the main list </itemize> </article>
<!doctype linuxdoc system> <article> <title>Quick Reference Sheet <author>David S. Lawyer <date>v1.0, July 2000 <abstract> abstract here </abstract> <toc> <!-- Comment: toc = Table of Contents -->
<sect> Chapter 1 Note: Put a <p> on the first line of <sect1> Subsection 1.1 each section (or subsection, etc.) <sect1> Subsection 1.2 <sect> Chapter 2 Choose title names to replace "Chapter" <sect1> Subsection 2.1 "Subsection", etc. <sect2> Sub-subsection 2.1.1 <sect2> Sub-subsection 2.1.2 <sect1> Subsection 2.2 </article>
There are two ways to get these:
<bf>boldface font</bf> <em>emphasis font</em> <sf>sans serif font</sf> <sl>slanted font</sl> <tt>typewriter font</tt> <it>italics font</it> <bf/boldface/ <em/emphasis/ <sf/sans serif/ <sl/slanted/ <tt/typewriter/ <it/italics/
Ordinary unnumbered list: Numbered list: <itemize> <enum> <item> First item <item> First item <item> Second item <item> Second item <item> etc. <item> etc. </itemize> </enum>
Cross-References: An Email Link: <ref id="links_" name="Links"> <url url="mailto:firstname.lastname@example.org">
To force a newline <newline> <tscreen><verb> <url url="http://www.linuxdoc.org"> <url url="http://www.linuxdoc.org" name="Linux Documentation Project">. </verb></tscreen>
You don't always need to use these.
&for the ampersand (&),
<for a left bracket (<),
>for a right bracket (>),
&etago;for a left bracket with a slash (
Use of these are optional and I seldom use them.
''for opening and closing double quotes
­for a soft hyphen (that is, an indication that this is a good place to break a very long word to insert a hyphen for horizontal justification).
Only use these if LinuxDoc complains about it or fails to generate them in the formated document. I've seldom had to use them.
$for a dollar sign ($),
#for a hash (#),
%for a percent (%),
˜for a tilde (~),
You could write a LinuxDoc document without having any LinuxDoc software. However, it's likely that it would contain some errors in the tags (or their use) so that it would be returned to you for correction. Even if there were no errors, the results might not not look quite right. So it's best for you to have the software to convert your source code on your computer.
The Debian distribution of Linux has a linuxdoc-tools package. There is also a rpm package for non-Debian distributions. It was formerly called sgml-tools. Don't use the sgmltools-2 package which is primarily for DocBook.
To use it, you run converter programs on the *.sgml files. For example, type: "sgml2txt -f my-HOWTO.sgml". To get html type: "sgml2html my-HOWTO.sgml". If it shows errors, it will show the line number and the column number where the error is in the source file. Typing "man -k sgml" should show you a number of other programs with a one-line description of each.
First email the HOWTO coordinator at mailto:email@example.com or mailto:firstname.lastname@example.org. If you're taking over an unmaintained HOWTO, contact the former author. This may required by the copyright-license but you should do it out of courtesy even it it's not required.
These are mostly by Tim Bynum (a former HOWTO coordinator).
After you have written the HOWTO, email the SGML source to email@example.com. Then all you need to do is to keep the HOWTO up-to date by submitting periodic updates to the same email as you used for the first edition.
There's a HOWTO: Linuxdoc-Reference that covers it in much greater detail than this mini-HOWTO.