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<span id="Shell-Conventions"></span><div class="header">
<p>
Next: <a href="Repository-Conventions.html" accesskey="n" rel="next">Repository Conventions</a>, Previous: <a href="General-Conventions.html" accesskey="p" rel="prev">General Conventions</a>, Up: <a href="Conventions.html" accesskey="u" rel="up">Conventions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>]</p>
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<hr>
<span id="Shell-Conventions-_002d_002d-10"></span><h4 class="subsection">3.1.2 Shell Conventions – 10</h4>
<p>Shell is central to Carbs Linux projects. Most of the tools and packages are
written in POSIX sh.
</p>
<dl compact="compact">
<dt><strong>[<span id="g_t1010"></span>1010]</strong></dt>
<dd><p>Use 4 spaces for indentation, don’t use tabs.
</p></dd>
<dt><strong>[<span id="g_t1020"></span>1020]</strong></dt>
<dd><p>Make sure you don’t use bash-specific code.
</p></dd>
<dt><strong>[<span id="g_t1030"></span>1030]</strong></dt>
<dd><p>Make sure you lint your code with <code>shellcheck</code> and if you are new to
POSIX sh, use <code>checkbashisms</code>.
</p></dd>
<dt><strong>[<span id="g_t1040"></span>1040]</strong></dt>
<dd><p>Don’t spawn new processes if you don’t absolutely need to, especially during
string manipulation.
</p><dl compact="compact">
<dt><strong>[<span id="g_t1041"></span>1041]</strong></dt>
<dd><p>Never use a program for text manupilation that isn’t defined in the POSIX
standard. This includes <code>gawk</code> and <code>perl</code>.
</p></dd>
<dt><strong>[<span id="g_t1042"></span>1042]</strong></dt>
<dd><p>Instead of <code>$(basename $file)</code>, use <code>${file##*}</code>.
</p></dd>
<dt><strong>[<span id="g_t1043"></span>1043]</strong></dt>
<dd><p>Instead of <code>$(dirname $file)</code>, use <code>${file%/*}</code>.
</p></dd>
</dl>
<div class="example">
<pre class="example"># This is the same thing as <code>basename /path/to/test.asc .asc</code>
$ file=/path/to/test.asc file=${file##*/} file=${file%.asc}
$ echo $file
test
</pre></div>
</dd>
<dt><strong>[<span id="g_t1050"></span>1050]</strong></dt>
<dd><p>Instead of backticks, use <tt>$(..)</tt>.
</p></dd>
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