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<h1 class="SECT1"><a name="CHAININGFILTERS">16.7. Chaining
Filters</a></h1>
<p>If a filter command has a pipe (<tt class=
"LITERAL">|</tt>) or IO redirection indicator (<tt class=
"LITERAL"><</tt> or <tt class="LITERAL">></tt>) in it,
or starts with an open parenthesis (<tt class=
"LITERAL">(</tt>), the filter is run by passing the entire
command to the shell specified by the <tt class=
"LITERAL">shell</tt> configuration option. This allows a wide
variety of options and operations to be carried out. The <tt
class="LITERAL">$*</tt> value should be used to have the
filter options passed to the correct entry in the filter
chain.</p>
<p>For example,</p>
<div class="INFORMALEXAMPLE">
<a name="AEN7881"></a>
<pre class="SCREEN">
lp:
:filter=( echo "starting `date`" >/var/log/status; /usr/local/ifhp $* )
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