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 branches
  10 --------
  11
  12 The online documentation published at <http://lttng.org/docs/> is always
  13 compiled from the sources of this repository's latest stable branch.
  14 The `master` branch contains the current documentation of the upcoming
  15 LTTng release.
  16
  17
  18 structure of sources
  19 --------------------
  20
  21 `toc/docs.yml` is a YAML tree of all chapters, sections and subsections.
  22 It indicates which unique ID is linked to which position in the
  23 hierarchy and its true title.
  24
  25 In the `contents` directory, the `preface.md` file is the preface contents.
  26 Each chapter has its own directory (directory names are not significant).
  27 Within those, `intro.md` files are partial introductions and then each
  28 section has its own directory, and so on, unless a section has no
  29 subsections, in which case all its contents is in a single Markdown file
  30 named _more or less_ like its ID.
  31
  32 Each Markdown file begins with a YAML front matter which only contains
  33 the unique ID of this chapter/section:
  34
  35 ```yaml
  36 ---
  37 id: unique-id-goes-here
  38 ---
  39
  40 First paragraph goes here.
  41 ```
  42
  43 Editable image sources are placed in `images/src` and their rendered
  44 equivalents are located in `images/export`.
  45
  46 `tools/checkdocs.py` is a Python 3 script which may be used to find
  47 typical errors in the whole documentation (dead internal links,
  48 common grammar mistakes, etc.). It needs the
  49 [`termcolor`](https://pypi.python.org/pypi/termcolor) Python package.
  50 Run it from the repository's root:
  51
  52     tools/checkdocs.py
  53
  54 and it will potentially output a list of errors and warnings.
  55
  56
  57 format of sources
  58 -----------------
  59
  60 The sources are made of a fusion of Markdown and HTML processed by
  61 [kramdown](http://kramdown.gettalong.org/). Markdown is preferred,
  62 HTML being only used for specific cases that need special formatting
  63 not available using plain Markdown. The kramdown processor is clever
  64 enough to support both languages in the same file, even in the same
  65 paragraph!
  66
  67
  68 ### HTML specifics
  69
  70 Here's a list of HTML blocks and inline code used throughout the
  71 document. If you need to contribute, please use them when needed to
  72 preserve the document's visual consistency.
  73
  74
  75 #### tip/note block
  76
  77 Tip/note block:
  78
  79 ```html
  80 <div class="tip">
  81     <p>
  82         <span class="t">Title goes here followed by colon:</span>Text goes
  83         here; plain HTML.
  84     </p>
  85     <p>
  86         Multiple paragraphs is allowed.
  87     </p>
  88 </div>
  89 ```
  90
  91 Title should be `Tip:` for a tip and `Note:` for a note.
  92
  93
  94 #### external links
  95
  96 Internal links should always use Markdown
  97 (`[caption](#doc-section)`). External links, however, need a special
  98 style and must use the `<a>` tag with the `ext` CSS class:
  99
 100 ```html
 101 The LTTng Documentation is
 102 <a href="https://github.com/lttng/lttng-docs" class="ext">public</a>.
 103 ```
 104
 105 Sometimes, however, it is necessary to write internal links in plain
 106 HTML, for example in tip blocks, since Markdown code is not processed.
 107 In these cases, add the `int` CSS class as a hint to prevent the static
 108 analyzer from complaining (`tools/checkdocs.py`).
 109
 110
 111 #### abbreviations
 112
 113 Use `<abbr>` for describing abbreviations. This should only be used
 114 for the first use of the abbreviation:
 115
 116 ```html
 117 The <abbr title="Linux Trace Toolkit: next generation">LTTng</abbr>
 118 project is an open source system software package [...]
 119 ```
 120
 121
 122 #### non-breaking spaces
 123
 124 Sometimes, a non-breaking space HTML entity (`&nbsp;`) needs to be
 125 explicitly written.
 126
 127 Examples:
 128
 129 ```html
 130 The size of this file is 1039&nbsp;bytes.
 131
 132 This integer is displayed in base&nbsp;16.
 133
 134 A check is performed every 3000&nbsp;ms.
 135 ```
 136
 137
 138 #### placeholders in inline code
 139
 140 You must use `<em>` to emphasize a placeholder within a `<code>` tag
 141 because Markdown backticks (<code>`</code>) always render their
 142 content literally:
 143
 144 ```html
 145 Name your file <code>something_<em>sys</em>.c</code>, where
 146 <code><em>sys</em></code> is your system name.
 147 ```
 148
 149
 150 #### terminal boxes
 151
 152 A terminal box, where command lines are shown, is a simple `<pre>`
 153 with the `term` class:
 154
 155 ```html
 156 <pre class="term">
 157 echo This is a terminal box
 158 </pre>
 159 ```
 160
 161 Do not prefix command lines with prompts (`$`/`#`) since this makes
 162 copy/paste operations painful.
 163
 164 You may use `<strong>` tags to emphasize a part of the command line:
 165
 166 ```html
 167 <pre class="term">
 168 echo This is a <strong>terminal</strong> box
 169 </pre>
 170 ```
 171
 172 Results of commands, if needed, should be presented in a simple
 173 `text` kramdown code block:
 174
 175 <pre>
 176 ~~~ text
 177 [15:30:34.835895035] (+?.?????????) hostname hello_world: { cpu_id = 1 }, { my_int = 8, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 178 [15:30:42.262781421] (+7.426886386) hostname hello_world: { cpu_id = 1 }, { my_int = 9, char0 = 80, char1 = 97, product = "Patriot Memory" }
 179 [15:30:48.175621778] (+5.912840357) hostname hello_world: { cpu_id = 1 }, { my_int = 10, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 180 ~~~
 181 </pre>
 182
 183
 184 #### images
 185
 186 Use
 187
 188 ```html
 189 <div class="img img-70">
 190     <img src="/images/docs26/image-name.png" alt="Short description">
 191 </div>
 192 ```
 193
 194 to display an image. Change `img-70` to `img-` followed by the
 195 width percentage you wish.
 196
 197 The SVG format is preferred. In this case, use the `<object>` tag to
 198 render an interactive SVG, with an inner raster image fallback for
 199 basic browsers:
 200
 201 ```html
 202 <div class="img img-90">
 203   <object data="/images/docs26/image-name.svg" type="image/svg+xml">
 204     <img src="/images/docs26/image-name.png" alt="Short description">
 205   </object>
 206 </div>
 207 ```
 208
 209 An interactive SVG object allows its text to be selected, amongst other
 210 features.
 211
 212
 213 convention
 214 ----------
 215
 216 A few rules to comply with in order to keep the text as
 217 consistent as possible:
 218
 219   * Use _user space_, not _userspace_ nor _user-space_.
 220     (neither _user land_).
 221   * Use _file system_, not _filesystem_.
 222   * Use _use case_, not _use-case_ nor _usecase_.
 223   * Use _the C standard library_, not _libc_.
 224   * Use _log level_, not _loglevel_.
 225   * Use complete LTTng project names: _LTTng-modules_, _LTTng-UST_ and
 226     _LTTng-tools_, not _modules_, _UST_ and _tools_.
 227   * All code snippets should use 4 spaces for indentation (even C)
 228     so that they are not too large.
 229   * Prefer emphasis (Markdown: `_something_`, HTML: `<em>something</em>`)
 230     to strong (Markdown: `**something**`, HTML: `<strong>something</strong>`)
 231     for emphasizing text.
 232   * Try to stay behind the 72th column mark if possible, and behind
 233     the 80th column otherwise.
 234   * Do not end directory paths with a forward slash
 235     (good: `include/trace/events`, bad: `include/trace/events/`).
 236   * Keep the text as impersonal as possible (minimize the use of
 237     _I_, _we_, _us_, etc.), except for user guides/tutorials where
 238     _we_ have an ongoing example.
 239
 240
 241 committing
 242 ----------
 243
 244 If you make a change to a single contents file, prefix your Git commit
 245 message's first line with the file ID followed by `: `, e.g:
 246
 247     archlinux: minor fix