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<th colspan="3" align="center">LPRng Reference Manual: 24
Sep 2004 (For LPRng-3.8.28)</th>
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<td width="80%" align="center" valign="bottom">Chapter
18. Accounting</td>
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<h1 class="SECT1"><a name="AEN9886">18.7. <b class=
"APPLICATION">LPRng</b> accounting.pl Utility</a></h1>
<p>The <b class="APPLICATION">LPRng</b> <tt class=
"FILENAME">accounting.pl</tt> utility provides the basic
framework for using the <var class="LITERAL">:as=|</var>,
<var class="LITERAL">:ae=|</var>, and pagecounter information
written to the accounting file to do reliable accounting, and
may be found in the <b class="APPLICATION">LPRng</b>
distribution <var class="LITERAL">UTILS</var> directory.
Usually this is modified according to local site needs and
installed in the filter directory.</p>
<p>The utility maintains the accounting file by inserting a
<var class="LITERAL">START</var> record at the start of a job
and an <var class="LITERAL">END</var> record at the end of
the job. It is assumed that the last <var class=
"LITERAL">END</var> record in the file marks the last place
that accounting was completed.</p>
<p>The following shows the printcap entry for using the <var
class="LITERAL">accounting.pl</var> utility. The <var class=
"LITERAL">start</var> and <var class="LITERAL">end</var>
options are used to specify that the utility is being called
at the job start or end.</p>
<div class="INFORMALEXAMPLE">
<a name="AEN9904"></a>
<pre class="SCREEN">
printer
:af=acct
:as=|/usr/local/libexec/filters/accounting.pl start
:ae=|/usr/local/libexec/filters/accounting.pl end
</pre>
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<br>
<br>
<p>At the start of each job the utilty writes a <var class=
"LITERAL">START</var> record into the accounting file. This
record can contain information suitable for use by local
site. The exit code and information written to the utility
<acronym class="ACRONYM">STDOUT</acronym> is used by the <var
class="LITERAL">lpd</var> server to determine if the job is
to be printed. This allows job quotas to be implemented in a
simple way by having the <var class=
"LITERAL">accounting.pl</var> utility query a database with
the user quotas and reject the job if the user's quota is
exceeded.</p>
<p>At the end of the job, the utilitity will read the
accounting file and use the recorded information to update
the accounting information. In order to make this reliable,
the following steps are taken.</p>
<ol type="1">
<li>
<p>The accounting file is read and scanned for the last
<var class="LITERAL">END</var> record. If there is none,
then the next step starts at the beginning of the
accounting file.</p>
</li>
<li>
<p>The file is scanned for <var class=
"LITERAL">START</var> lines and <var class=
"LITERAL">pagecounter</var> information determined at the
start of a job.</p>
</li>
<li>
<p>If the last line in the accounting file does not
indicate successful completetion of the job and contain
pagecounting information, then the accounting procedure
is abandoned until the next job completes
successfully.</p>
</li>
<li>
<p>If the last line in the accounting file indicates
successful completion, then its pagecounter value is used
as the last page counter value.</p>
</li>
<li>
<p>Job information is updated by finding the start and
end pagecounter values for each job. It is possible that
a job will not have a pagecounter value recorded at its
start; in this case the page usage will be 0, as it did
not even get initialized.</p>
</li>
<li>
<p>After determining the accounting information, the
procedure will then update and databases and the
accounting file. During this update, interrupts should be
disabled and the amount of time taken to update the
accounting information and/or file should be
minimized.</p>
</li>
</ol>
<br>
<br>
<p>Administrators can use this script as a starting point for
more advanced accounting. For example, rather than just
recording the information, at the job start the script can
query either a local database or a remote server to see if
the user has permissions to access the printer. At the end of
the job or when an <acronym class="ACRONYM">END</acronym>
line is written to the accounting file, the local database or
remote accounting server can be updated.</p>
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