contrib-guide.md

   1 Contributor's guide
   2 ===================
   3
   4 This guide presents the structure and conventions of the LTTng
   5 Documentation's source. Make sure you read it thoroughly before
   6 contributing a change.
   7
   8
   9 structure
  10 ---------
  11
  12 `toc/docs.yml` is a YAML tree of all chapters, sections and subsections.
  13 It indicates which unique ID is linked to which position in the
  14 hierarchy and its true title.
  15
  16 In the `contents` directory, the `preface.md` file is the preface contents.
  17 Each chapter has its own directory (directory names are not significant).
  18 Within those, `intro.md` files are partial introductions and then each
  19 section has its own directory, and so on, unless a section has no
  20 subsections, in which case all its contents is in a single Markdown file
  21 named _more or less_ like its ID.
  22
  23 Each Markdown file begins with a YAML front matter which only contains
  24 the unique ID of this chapter/section:
  25
  26 ```yaml
  27 ---
  28 id: unique-id-goes-here
  29 ---
  30
  31 First paragraph goes here.
  32 ```
  33
  34 Editable image sources are placed in `images/src` and their rendered
  35 equivalents are located in `images/export`.
  36
  37 `tools/checkdocs.py` is a Python 3 script which may be used to find
  38 typical errors in the whole documentation (dead internal links,
  39 common grammar mistakes, etc.). It needs the
  40 [`termcolor`](https://pypi.python.org/pypi/termcolor) Python package.
  41 Run it from the repository's root:
  42
  43     tools/checkdocs.py
  44
  45 and it will potentially output a list of errors and warnings.
  46
  47
  48 format of sources
  49 -----------------
  50
  51 The sources are made of a fusion of Markdown and HTML processed by
  52 [kramdown](http://kramdown.gettalong.org/). Markdown is preferred,
  53 HTML being only used for specific cases that need special formatting
  54 not available using plain Markdown. The kramdown processor is clever
  55 enough to support both languages in the same file, even in the same
  56 paragraph!
  57
  58
  59 ### HTML specifics
  60
  61 Here's a list of HTML blocks and inline code used throughout the
  62 document. If you need to contribute, please use them when needed to
  63 preserve the document's visual consistency.
  64
  65
  66 #### tip/note block
  67
  68 Tip/note block:
  69
  70 ```html
  71 <div class="tip">
  72     <p>
  73         <span class="t">Title goes here followed by colon:</span>Text goes
  74         here; plain HTML.
  75     </p>
  76     <p>
  77         Multiple paragraphs is allowed.
  78     </p>
  79 </div>
  80 ```
  81
  82 Title should be `Tip:` for a tip and `Note:` for a note.
  83
  84
  85 #### external links
  86
  87 Internal links should always use Markdown
  88 (`[caption](#doc-section)`). External links, however, need a special
  89 style and must use the `<a>` tag with the `ext` CSS class:
  90
  91 ```html
  92 The LTTng Documentation is
  93 <a href="https://github.com/lttng/lttng-docs" class="ext">public</a>.
  94 ```
  95
  96
  97 #### abbreviations
  98
  99 Use `<abbr>` for describing abbreviations. This should only be used
 100 for the first use of the abbreviation:
 101
 102 ```html
 103 The <abbr title="Linux Trace Toolkit: next generation">LTTng</abbr>
 104 project is an open source system software package [...]
 105 ```
 106
 107
 108 #### non-breaking spaces
 109
 110 Sometimes, a non-breaking space HTML entity (`&nbsp;`) needs to be
 111 explicitly written.
 112
 113 Examples:
 114
 115 ```html
 116 The size of this file is 1039&nbsp;bytes.
 117
 118 This integer is displayed in base&nbsp;16.
 119
 120 A check is performed every 3000&nbsp;ms.
 121 ```
 122
 123
 124 #### placeholders in inline code
 125
 126 You must use `<em>` to emphasize a placeholder within a `<code>` tag
 127 because Markdown backticks (<code>`</code>) always render their
 128 content literally:
 129
 130 ```html
 131 Name your file <code>something_<em>sys</em>.c</code>, where
 132 <code><em>sys</em></code> is your system name.
 133 ```
 134
 135
 136 #### terminal boxes
 137
 138 A terminal box, where command lines are shown, is a simple `<pre>`
 139 with the `term` class:
 140
 141 ```html
 142 <pre class="term">
 143 echo This is a terminal box
 144 </pre>
 145 ```
 146
 147 Do not prefix command lines with prompts (`$`/`#`) since this makes
 148 copy/paste operations painful.
 149
 150 You may use `<strong>` tags to emphasize a part of the command line:
 151
 152 ```html
 153 <pre class="term">
 154 echo This is a <strong>terminal</strong> box
 155 </pre>
 156 ```
 157
 158 Results of commands, if needed, should be presented in a simple
 159 `text` kramdown code block:
 160
 161 <pre>
 162 ~~~ text
 163 [15:30:34.835895035] (+?.?????????) hostname hello_world: { cpu_id = 1 }, { my_int = 8, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 164 [15:30:42.262781421] (+7.426886386) hostname hello_world: { cpu_id = 1 }, { my_int = 9, char0 = 80, char1 = 97, product = "Patriot Memory" }
 165 [15:30:48.175621778] (+5.912840357) hostname hello_world: { cpu_id = 1 }, { my_int = 10, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 166 ~~~
 167 </pre>
 168
 169
 170 #### images
 171
 172 Use
 173
 174 ```html
 175 <div class="img img-70">
 176     <img src="/images/docs/image-name.png" alt="Short description">
 177 </div>
 178 ```
 179
 180 to display an image. Change `img-70` to `img-` followed by the
 181 width percentage you wish.
 182
 183 The SVG format is preferred. In this case, use the `<object>` tag to
 184 render an interactive SVG, with an inner raster image fallback for
 185 basic browsers:
 186
 187 ```html
 188 <div class="img img-90">
 189   <object data="/images/docs/image-name.svg" type="image/svg+xml">
 190     <img src="/images/docs/image-name.png" alt="Short description">
 191   </object>
 192 </div>
 193 ```
 194
 195 An interactive SVG object allows its text to be selected, amongst other
 196 features.
 197
 198
 199 convention
 200 ----------
 201
 202 A few rules to comply with in order to keep the text as
 203 consistent as possible:
 204
 205   * Use _user space_, not _userspace_ nor _user-space_.
 206     (neither _user land_).
 207   * Use _file system_, not _filesystem_.
 208   * Use _use case_, not _use-case_ nor _usecase_.
 209   * Use _the C standard library_, not _libc_.
 210   * Use _log level_, not _loglevel_.
 211   * Use complete LTTng project names: _LTTng-modules_, _LTTng-UST_ and
 212     _LTTng-tools_, not _modules_, _UST_ and _tools_.
 213   * All code snippets should use 4 spaces for indentation (even C)
 214     so that they are not too large.
 215   * Prefer emphasis (Markdown: `_something_`, HTML: `<em>something</em>`)
 216     to strong (Markdown: `**something**`, HTML: `<strong>something</strong>`)
 217     for emphasizing text.
 218   * Try to stay behind the 72th column mark if possible, and behind
 219     the 80th column otherwise.
 220   * Do not end directory paths with a forward slash
 221     (good: `include/trace/events`, bad: `include/trace/events/`).
 222   * Keep the text as impersonal as possible (minimize the use of
 223     _I_, _we_, _us_, etc.), except for user guides/tutorials where
 224     _we_ have an ongoing example.