($) helps to avoid some parens.  The (.) is more common to change functions, and closely related.  ($) does not really compose functions, it is function application and right associative.<p>Your example would rather read something close to<p><pre><code>  sort -n . uniq -n . sort . awk '{ print $5}' . grep tcp . netstat -n
</code></pre>
(And `$ argument' at the end, if there was one.)