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/warning/error blocks
  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 Replace the `tip` class with `warn` for a warning block, and with `err`
  92 for an error message block (when JavaScript is needed but is disabled, etc.).
  93
  94 Title should be `Tip:` for a tip, `Note:` for a note, `Warning:` for a
  95 warning, and `Error:` for an error.
  96
  97
  98 #### External links
  99
 100 Internal links should always use Markdown
 101 (`[caption](#doc-section)`). External links, however, need a special
 102 style and must use the `<a>` tag with the `ext` CSS class:
 103
 104 ```html
 105 The LTTng Documentation is
 106 <a href="https://github.com/lttng/lttng-docs" class="ext">public</a>.
 107 ```
 108
 109 Sometimes, however, it is necessary to write internal links in plain
 110 HTML, for example in tip blocks, since Markdown code is not processed.
 111 In these cases, add the `int` CSS class as a hint to prevent the static
 112 analyzer from complaining (`tools/checkdocs.py`).
 113
 114
 115 #### Abbreviations
 116
 117 Use `<abbr>` for describing abbreviations. This should only be used
 118 for the first use of the abbreviation:
 119
 120 ```html
 121 The <abbr title="Linux Trace Toolkit: next generation">LTTng</abbr>
 122 project is an open source system software package [...]
 123 ```
 124
 125
 126 #### Non-breaking spaces
 127
 128 Sometimes, a non-breaking space HTML entity (`&nbsp;`) needs to be
 129 explicitly written.
 130
 131 Examples:
 132
 133 ```html
 134 The size of this file is 1039&nbsp;bytes.
 135
 136 This integer is displayed in base&nbsp;16.
 137
 138 A check is performed every 3000&nbsp;ms.
 139 ```
 140
 141
 142 #### Placeholders in inline code
 143
 144 You must use `<em>` to emphasize a placeholder within a `<code>` tag
 145 because Markdown backticks (<code>`</code>) always render their
 146 content literally:
 147
 148 ```html
 149 Name your file <code>something_<em>sys</em>.c</code>, where
 150 <code><em>sys</em></code> is your system name.
 151 ```
 152
 153
 154 #### Terminal boxes
 155
 156 A terminal box, where command lines are shown, is a simple `<pre>`
 157 with the `term` class:
 158
 159 ```html
 160 <pre class="term">
 161 echo This is a terminal box
 162 </pre>
 163 ```
 164
 165 Do not prefix command lines with prompts (`$`/`#`) since this makes
 166 copy/paste operations painful.
 167
 168 You may use `<strong>` tags to emphasize a part of the command line:
 169
 170 ```html
 171 <pre class="term">
 172 echo This is a <strong>terminal</strong> box
 173 </pre>
 174 ```
 175
 176 Results of commands, if needed, should be presented in a simple
 177 `text` kramdown code block:
 178
 179 <pre>
 180 ~~~ text
 181 [15:30:34.835895035] (+?.?????????) hostname hello_world: { cpu_id = 1 }, { my_int = 8, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 182 [15:30:42.262781421] (+7.426886386) hostname hello_world: { cpu_id = 1 }, { my_int = 9, char0 = 80, char1 = 97, product = "Patriot Memory" }
 183 [15:30:48.175621778] (+5.912840357) hostname hello_world: { cpu_id = 1 }, { my_int = 10, char0 = 68, char1 = 97, product = "DataTraveler 2.0" }
 184 ~~~
 185 </pre>
 186
 187
 188 #### Images
 189
 190 Use
 191
 192 ```html
 193 <figure class="img img-70">
 194     <img src="/images/docs26/image-name.png" alt="Short description">
 195 </figure>
 196 ```
 197
 198 Replace `docs26` with the appropriate version tag depending on the
 199 checked out branch.
 200
 201 to display an image. Change `img-70` to `img-` followed by the
 202 width percentage you wish.
 203
 204
 205 Convention
 206 ----------
 207
 208 A few rules to comply with in order to keep the text as
 209 consistent as possible:
 210
 211   * Use _user space_, not _userspace_ nor _user-space_.
 212     (neither _user land_).
 213   * Use _file system_, not _filesystem_.
 214   * Use _use case_, not _use-case_ nor _usecase_.
 215   * Use _the C standard library_, not _libc_.
 216   * Use _log level_, not _loglevel_.
 217   * Use complete LTTng project names: _LTTng-modules_, _LTTng-UST_ and
 218     _LTTng-tools_, not _modules_, _UST_ and _tools_.
 219   * All code snippets should use 4 spaces for indentation (even C)
 220     so that they are not too large.
 221   * Prefer emphasis (Markdown: `_something_`, HTML: `<em>something</em>`)
 222     to strong (Markdown: `**something**`, HTML: `<strong>something</strong>`)
 223     for emphasizing text.
 224   * Try to stay behind the 72th column mark if possible, and behind
 225     the 80th column otherwise.
 226   * Do not end directory paths with a forward slash
 227     (good: `include/trace/events`, bad: `include/trace/events/`).
 228   * Keep the text as impersonal as possible (minimize the use of
 229     _I_, _we_, _us_, etc.), except for user guides/tutorials where
 230     _we_ have an ongoing example with _you_.
 231   * Minimize the use of the future tense (_will_).
 232   * Do not use Latin abbreviations (_e.g._, _i.e._, _etc._).
 233
 234
 235 Committing
 236 ----------
 237
 238 If you make a change to a single contents file, prefix your Git commit
 239 message's first line with the file ID followed by `: `, e.g:
 240
 241     archlinux: minor fix