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Document passed() in the config basics document

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Signed-off-by: Tom Eastep <teastep@shorewall.net>
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Tom Eastep 2016-03-15 15:19:21 -07:00
parent da0653cb2f
commit 5fc391cb58
1 changed files with 28 additions and 1 deletions
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29
docs/configuration_file_basics.xml
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@ -1985,6 +1985,33 @@ SSH(ACCEPT) net:$MYIP $FW
@disposition are used to generated the --log-prefix in logging rules. When
either is empty, the historical value is used to generate the
--log-prefix.</para>
<para>Within an action body, if a parameter is omitted in a DEFAULTS
statement, then the value of the corresponding action and Shorewall
variables is '-', while if the parameter is specified as '-' in the
parameter list, the value of the action/Shorewall variable is '', if it is
expanded before the DEFAULTS statement.</para>
<para>Additionally, when an expression is evaluated, the value 0 evaluates
as false, so '?IF @n' and '?IF $n' fail if the nth parameter is passed
with value zero. To make testing of the presense of parameters more
efficient and uniform, an new function has been added in Shorewall 5.0.7
for use in ?IF and ?ELSEIF:</para>
<simplelist>
<member>?IF [!] passed(&lt;variable&gt;)</member>
</simplelist>
<para>where &lt;variable&gt; is an action or Shorewall variable.</para>
<para>'passed(@n)' and 'passed($n)' evaluate to true if the nth parameter
is not empty and its contents are other than '-'. If '!' is present, the
result is inverted.</para>
<para>In this simple form, the expression is evaluated by the compiler
without having to invoke the (expensive) Perl exec() function. The
'passed' function may also be used in more complex expressions, but exec()
will be invoked to evaluate those expressions. </para>
</section>
<section id="Conditional">
@ -2175,7 +2202,7 @@ SSH(ACCEPT) net:$MYIP $FW
<programlisting>?ERROR <replaceable>message</replaceable></programlisting>
<para>Variables in the message are evaluated and the result appears in a
standard Shorewall ERROR: message. </para>
standard Shorewall ERROR: message.</para>
<para>Example from the 5.0.7 action.GlusterFS:</para>