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<h1>Coding Style</h1>
<h2 id="bash-and-shell"><a class="toclink" href="#bash-and-shell">Bash and Shell</a></h2>
<p>When refactoring, writing or altering scripts, that is Shell and bash scripts, in any way, adhere to these rules:</p>
<ol>
<li><strong>Adjust your style of coding to the style that is already present</strong>! Even if you do not like it, this is due to consistency. There was a lot of work involved in making all scripts consistent.</li>
<li><strong>Use <code>shellcheck</code> to check your scripts</strong>! Your contributions are checked by GitHub Actions too, so you will need to do this. You can <strong>lint your work with <code>make lint</code></strong> to check against all targets.</li>
<li><strong>Use the provided <code>.editorconfig</code></strong> file.</li>
<li>Use <code>/bin/bash</code> instead of <code>/bin/sh</code>. Adjust the style accordingly.</li>
<li><code>setup.sh</code> provides a good starting point to look for.</li>
<li>When appropriate, use the <code>set</code> builtin. We recommend <code>set -euEo pipefail</code> or <code>set -uE</code>.</li>
</ol>
<h2 id="styling-rules"><a class="toclink" href="#styling-rules">Styling rules</a></h2>
<h3 id="if-else-statements"><a class="toclink" href="#if-else-statements">If-Else-Statements</a></h3>
<div class="highlight"><pre><span></span><code><span class="c1"># when using braces, use double braces</span>
<span class="c1"># remember you do not need &quot;&quot; when using [[ ]]</span>
<span class="k">if</span> <span class="o">[[</span> &lt;CONDITION1&gt; <span class="o">]]</span> <span class="o">&amp;&amp;</span> <span class="o">[[</span> -f <span class="si">${</span><span class="nv">FILE</span><span class="si">}</span> <span class="o">]]</span>
<span class="k">then</span>
&lt;CODE TO RUN&gt;
<span class="c1"># when running commands, you don&#39;t need braces</span>
<span class="k">elif</span> &lt;COMMAND TO RUN&gt;
&lt;CODE TO TUN&gt;
<span class="k">else</span>
&lt;CODE TO TUN&gt;
<span class="k">fi</span>
<span class="c1"># equality checks with numbers are done</span>
<span class="c1"># with -eq/-ne/-lt/-ge, not != or ==</span>
<span class="k">if</span> <span class="o">[[</span> <span class="si">${</span><span class="nv">VAR</span><span class="si">}</span> -ne <span class="m">42</span> <span class="o">]]</span> <span class="o">||</span> <span class="o">[[</span> <span class="si">${</span><span class="nv">SOME_VAR</span><span class="si">}</span> -eq <span class="m">6</span> <span class="o">]]</span>
<span class="k">then</span>
&lt;CODE TO RUN&gt;
<span class="k">fi</span>
</code></pre></div>
<h3 id="variables-braces"><a class="toclink" href="#variables-braces">Variables &amp; Braces</a></h3>
<div class="admonition attention">
<p class="admonition-title">Attention</p>
<p>Variables are always uppercase. We always use braces.</p>
</div>
<p>If you forgot this and want to change it later, you can use <a href="https://regex101.com/r/ikzJpF/7">this link</a>. The used regex is <code>\$([^{("\\'\/])([a-zA-Z0-9_]*)([^}\/ \t'"\n.\]:(=\\-]*)</code>, where you should in practice be able to replace all variable occurrences without braces with occurrences with braces.</p>
<div class="highlight"><pre><span></span><code><span class="c1"># good</span>
<span class="nb">local</span> <span class="nv">VAR</span><span class="o">=</span><span class="s2">&quot;good&quot;</span>
<span class="nb">local</span> <span class="nv">NEW</span><span class="o">=</span><span class="s2">&quot;</span><span class="si">${</span><span class="nv">VAR</span><span class="si">}</span><span class="s2">&quot;</span>
<span class="c1"># bad -&gt; TravisCI will fail</span>
<span class="nv">var</span><span class="o">=</span><span class="s2">&quot;bad&quot;</span>
<span class="nv">new</span><span class="o">=</span><span class="nv">$var</span>
</code></pre></div>
<h3 id="loops"><a class="toclink" href="#loops">Loops</a></h3>
<p>Like <code>if-else</code>, loops look like this</p>
<div class="highlight"><pre><span></span><code><span class="k">for</span> / <span class="k">while</span> &lt;LOOP CONDITION&gt;
<span class="k">do</span>
&lt;CODE TO RUN&gt;
<span class="k">done</span>
</code></pre></div>
<h3 id="functions"><a class="toclink" href="#functions">Functions</a></h3>
<p>It's always nice to see the use of functions as it also provides a clear structure. If scripts are small, this is unnecessary, but if they become larger, please consider using functions. When doing so, provide <code>function _main</code>.</p>
<div class="highlight"><pre><span></span><code><span class="k">function</span> _&lt;name_underscored_and_lowercase&gt;
<span class="o">{</span>
&lt;CODE TO RUN&gt;
<span class="c1"># variables that can be local should be local</span>
<span class="nb">local</span> &lt;LOCAL_VARIABLE_NAME&gt;
<span class="o">}</span>
</code></pre></div>
<h3 id="error-tracing"><a class="toclink" href="#error-tracing">Error Tracing</a></h3>
<p>A construct to trace error in your scripts looks like this. Remember: Remove <code>set -x</code> in the end. This is for debugging purposes only.</p>
<div class="highlight"><pre><span></span><code><span class="nb">set</span> -xeuEo pipefail
<span class="nb">trap</span> <span class="s1">&#39;__log_err ${FUNCNAME[0]:-&quot;?&quot;} ${BASH_COMMAND:-&quot;?&quot;} ${LINENO:-&quot;?&quot;} ${?:-&quot;?&quot;}&#39;</span> ERR
<span class="nv">SCRIPT</span><span class="o">=</span><span class="s1">&#39;name_of_this_script.sh&#39;</span>
<span class="k">function</span> __log_err
<span class="o">{</span>
<span class="nb">printf</span> <span class="s2">&quot;\n––– \e[1m\e[31mUNCHECKED ERROR\e[0m\n%s\n%s\n%s\n%s\n\n&quot;</span> <span class="se">\</span>
<span class="s2">&quot; – script = </span><span class="si">${</span><span class="nv">SCRIPT</span><span class="k">:-</span><span class="si">${</span><span class="nv">0</span><span class="si">}}</span><span class="s2">&quot;</span> <span class="se">\</span>
<span class="s2">&quot; – function = </span><span class="si">${</span><span class="nv">1</span><span class="si">}</span><span class="s2"> / </span><span class="si">${</span><span class="nv">2</span><span class="si">}</span><span class="s2">&quot;</span> <span class="se">\</span>
<span class="s2">&quot; – line = </span><span class="si">${</span><span class="nv">3</span><span class="si">}</span><span class="s2">&quot;</span> <span class="se">\</span>
<span class="s2">&quot; – exit code = </span><span class="si">${</span><span class="nv">4</span><span class="si">}</span><span class="s2">&quot;</span> <span class="m">1</span>&gt;<span class="p">&amp;</span><span class="m">2</span>
&lt;CODE TO RUN AFTERWARDS&gt;
<span class="o">}</span>
</code></pre></div>
<h3 id="comments-descriptiveness-an-example"><a class="toclink" href="#comments-descriptiveness-an-example">Comments, Descriptiveness &amp; An Example</a></h3>
<p>Comments should only describe non-obvious matters. Comments should start lowercase when they aren't sentences. Make the code <strong>self-descriptive</strong> by using meaningful names! Make comments not longer than approximately 80 columns, then wrap the line.</p>
<p>A positive example, which is taken from <code>start-mailserver.sh</code>, would be</p>
<div class="highlight"><pre><span></span><code><span class="k">function</span> _setup_postfix_aliases
<span class="o">{</span>
_notify <span class="s1">&#39;task&#39;</span> <span class="s1">&#39;Setting up Postfix Aliases&#39;</span>
: &gt;/etc/postfix/virtual
: &gt;/etc/postfix/regexp
<span class="k">if</span> <span class="o">[[</span> -f /tmp/docker-mailserver/postfix-virtual.cf <span class="o">]]</span>
<span class="k">then</span>
<span class="c1"># fixing old virtual user file</span>
<span class="k">if</span> grep -q <span class="s2">&quot;,</span>$<span class="s2">&quot;</span> /tmp/docker-mailserver/postfix-virtual.cf
<span class="k">then</span>
sed -i -e <span class="s2">&quot;s/, /,/g&quot;</span> -e <span class="s2">&quot;s/,</span>$<span class="s2">//g&quot;</span> /tmp/docker-mailserver/postfix-virtual.cf
<span class="k">fi</span>
cp -f /tmp/docker-mailserver/postfix-virtual.cf /etc/postfix/virtual
<span class="c1"># the `to` is important, don&#39;t delete it</span>
<span class="c1"># shellcheck disable=SC2034</span>
<span class="k">while</span> <span class="nb">read</span> -r FROM TO
<span class="k">do</span>
<span class="c1"># Setting variables for better readability</span>
<span class="nv">UNAME</span><span class="o">=</span><span class="k">$(</span><span class="nb">echo</span> <span class="s2">&quot;</span><span class="si">${</span><span class="nv">FROM</span><span class="si">}</span><span class="s2">&quot;</span> <span class="p">|</span> cut -d @ -f1<span class="k">)</span>
<span class="nv">DOMAIN</span><span class="o">=</span><span class="k">$(</span><span class="nb">echo</span> <span class="s2">&quot;</span><span class="si">${</span><span class="nv">FROM</span><span class="si">}</span><span class="s2">&quot;</span> <span class="p">|</span> cut -d @ -f2<span class="k">)</span>
<span class="c1"># if they are equal it means the line looks like: &quot;user1 other@domain.tld&quot;</span>
<span class="o">[[</span> <span class="s2">&quot;</span><span class="si">${</span><span class="nv">UNAME</span><span class="si">}</span><span class="s2">&quot;</span> !<span class="o">=</span> <span class="s2">&quot;</span><span class="si">${</span><span class="nv">DOMAIN</span><span class="si">}</span><span class="s2">&quot;</span> <span class="o">]]</span> <span class="o">&amp;&amp;</span> <span class="nb">echo</span> <span class="s2">&quot;</span><span class="si">${</span><span class="nv">DOMAIN</span><span class="si">}</span><span class="s2">&quot;</span> &gt;&gt; /tmp/vhost.tmp
<span class="k">done</span> &lt; &lt;<span class="o">(</span>grep -v <span class="s2">&quot;^\s*</span>$<span class="s2">\|^\s*\#&quot;</span> /tmp/docker-mailserver/postfix-virtual.cf <span class="o">||</span> <span class="nb">true</span><span class="o">)</span>
<span class="k">else</span>
_notify <span class="s1">&#39;inf&#39;</span> <span class="s2">&quot;Warning &#39;config/postfix-virtual.cf&#39; is not provided. No mail alias/forward created.&quot;</span>
<span class="k">fi</span>
...
<span class="o">}</span>
</code></pre></div>
<h2 id="yaml"><a class="toclink" href="#yaml">YAML</a></h2>
<p>When formatting YAML files, use <a href="https://prettier.io">Prettier</a>, an opinionated formatter. There are many plugins for IDEs around.</p>
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