1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2 3<html> 4 <head> 5 <meta name="generator" content="HTML Tidy, see www.w3.org"> 6 <title>OF Filter</title> 7 <meta name="GENERATOR" content= 8 "Modular DocBook HTML Stylesheet Version 1.7"> 9 <link rel="HOME" title=" LPRng Reference Manual" href= 10 "index.htm"> 11 <link rel="UP" title="Filters " href="filters.htm"> 12 <link rel="PREVIOUS" title="Print Job Formats " href= 13 "printjobformats.htm"> 14 <link rel="NEXT" title="lpr -p format " href="pr.htm"> 15 </head> 16 17 <body class="SECT1" bgcolor="#FFFFFF" text="#000000" link= 18 "#0000FF" vlink="#840084" alink="#0000FF"> 19 <div class="NAVHEADER"> 20 <table summary="Header navigation table" width="100%" border= 21 "0" cellpadding="0" cellspacing="0"> 22 <tr> 23 <th colspan="3" align="center">LPRng Reference Manual: 5 24 Sep 2003 (For LPRng-3.8.22)</th> 25 </tr> 26 27 <tr> 28 <td width="10%" align="left" valign="bottom"><a href= 29 "printjobformats.htm" accesskey="P">Prev</a></td> 30 31 <td width="80%" align="center" valign="bottom">Chapter 32 16. Filters</td> 33 34 <td width="10%" align="right" valign="bottom"><a href= 35 "pr.htm" accesskey="N">Next</a></td> 36 </tr> 37 </table> 38 <hr align="LEFT" width="100%"> 39 </div> 40 41 <div class="SECT1"> 42 <h1 class="SECT1"><a name="OFDETAILS">16.4. OF 43 Filter</a></h1> 44 45 <p>The <var class="LITERAL">:of</var> filter is used to 46 process banners and job separators. The <var class= 47 "LITERAL">:of</var> filter is responsible for performing 48 appropriate processing of this information and sending to the 49 printer for action.</p> 50 51 <p>While the various file filters are invoked on a once per 52 print file basis, the <var class="LITERAL">:of</var> filter 53 is invoked on a once per print job basis.</p> 54 55 <p>This filter is the first one to be started, and should 56 perform whatever specialized device initialization is needed. 57 It should also do whatever accounting procedure is desired 58 for start of job accounting.</p> 59 60 <p>The <var class="LITERAL">:of</var> filter will be given 61 any banner printing or job separation information for a job. 62 As part of its operation, it can detect a specific string, 63 corresponding to a banner print request, and generate a 64 banner. (See the <a href="jobsteps.htm">Job Processing Steps 65 and Printcap Options</a> for details.)</p> 66 67 <p>During operation, the <b class="APPLICATION">lpd</b> 68 server will send the special <span class="emphasis"><i class= 69 "EMPHASIS">stop</i></span> sequence of <var class= 70 "LITERAL">\031\001</var> to the <var class= 71 "LITERAL">:of</var> filter. The filter must then suspend 72 itself using a <tt class="COMMAND">kill -STOP</tt> operation. 73 The <b class="APPLICATION">lpd</b> server will detect that 74 the <var class="LITERAL">:of</var> filter has suspended 75 itself and then will perform other printing operations.</p> 76 77 <p>After the other printing operations have been completed, 78 the <var class="LITERAL">:of</var> will then be sent a <tt 79 class="COMMAND">kill -CONT</tt> signal.</p> 80 81 <p>This sequence will continue until all information has been 82 printed, and then the <var class="LITERAL">:of</var> filter's 83 <acronym class="ACRONYM">STDIN</acronym> will be closed. The 84 filter will then perform whatever cleanup operations are 85 needed, update accounting or other information, and exit.</p> 86 </div> 87 88 <div class="NAVFOOTER"> 89 <hr align="LEFT" width="100%"> 90 91 <table summary="Footer navigation table" width="100%" border= 92 "0" cellpadding="0" cellspacing="0"> 93 <tr> 94 <td width="33%" align="left" valign="top"><a href= 95 "printjobformats.htm" accesskey="P">Prev</a></td> 96 97 <td width="34%" align="center" valign="top"><a href= 98 "index.htm" accesskey="H">Home</a></td> 99 100 <td width="33%" align="right" valign="top"><a href= 101 "pr.htm" accesskey="N">Next</a></td> 102 </tr> 103 104 <tr> 105 <td width="33%" align="left" valign="top">Print Job 106 Formats</td> 107 108 <td width="34%" align="center" valign="top"><a href= 109 "filters.htm" accesskey="U">Up</a></td> 110 111 <td width="33%" align="right" valign="top"><b class= 112 "APPLICATION">lpr</b> -p format</td> 113 </tr> 114 </table> 115 </div> 116 </body> 117</html> 118 119