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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<th colspan="3" align="center">LPRng-HOWTO: 1 Apr 2002
(For LPRng-3.8.10)</th>
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<div class="CHAPTER">
<h1><a name="PRINTCAPREF">Chapter 12. Printcap
Database</a></h1>
<div class="TOC">
<dl>
<dt><b>Table of Contents</b></dt>
<dt>12.1. <a href="printcapref.htm#PRINTCAPPARSE">The
Printcap Parsing Rules</a></dt>
<dt>12.2. <a href="simple.htm">Simple Client Printcap
Entry</a></dt>
<dt>12.3. <a href="cm.htm">Simple Server Printcap
Example</a></dt>
<dt>12.4. <a href="x5679.htm">Using :oh To Select
Printcap Information</a></dt>
<dt>12.5. <a href="x5705.htm">Using the Wildcard Printcap
Entry</a></dt>
<dt>12.6. <a href="x5717.htm">Enterprise Strength
Printcap Example</a></dt>
<dt>12.7. <a href="x5734.htm">Remote Printer Using
RFC1179</a></dt>
<dt>12.8. <a href="x5768.htm">Remote Printer Using Socket
API</a></dt>
<dt>12.9. <a href="x5795.htm">Parallel Printer</a></dt>
<dt>12.10. <a href="serial.htm">Serial Printer</a></dt>
<dt>12.11. <a href="lpdbounce.htm">Bounce Queue</a></dt>
<dt>12.12. <a href="translateformat.htm">Job Format
Translation</a></dt>
<dt>12.13. <a href="destinations.htm">Dynamic
Routing</a></dt>
<dt>12.14. <a href="loadbalance.htm">Printer Load
Balancing</a></dt>
<dt>12.15. <a href="printcappath.htm">Locations of
Printcap Files</a></dt>
<dt>12.16. <a href="secoh.htm">Single Printcap File for
Large Installation</a></dt>
<dt>12.17. <a href="x6065.htm">Management Strategies for
Large Installations</a></dt>
<dt>12.18. <a href="secnis.htm">Using Programs To Get
Printcap Information</a></dt>
<dt>12.19. <a href="x6175.htm">Lexmark Printers</a></dt>
<dt>12.20. <a href="p450.htm">Tektronix Phaser
Printers</a></dt>
<dt>12.21. <a href="x6189.htm">Duplex Printing</a></dt>
<dt>12.22. <a href="x6210.htm">Solaris, Newsprint and
FrameMaker</a></dt>
</dl>
</div>
<p>As described in the <a href="tutorial.htm#OVERVIEW">Print
Spooling Overview</a>, the heart of the <b class=
"APPLICATION">LPRng</b> system is information in the <tt
class="FILENAME">printcap</tt> file. The printcap information
specifies:</p>
<ol type="1">
<li>
<p>The print queues available to users.</p>
</li>
<li>
<p>How client programs communicate with the <b class=
"APPLICATION">lpc</b> print server.</p>
</li>
<li>
<p>The configuration, location, and other information for
each print queue on the print server.</p>
</li>
<li>
<p>How the <b class="APPLICATION">lpd</b> server
processes jobs in each print queue.</p>
</li>
</ol>
<br>
<br>
<p>In order to explain a complex subject, we will start with
a set of simple printer configurations, and explain the
purpose and effect of each entry in the printcap.</p>
<p>For details about individual printcap options, see the
<span class="CITEREFENTRY"><span class=
"REFENTRYTITLE">printcap</span>(5)</span> man page from the
<b class="APPLICATION">LPRng</b> distribution, or use the <a
href="optionindex.htm">Index To All The Configuration and
Printcap Options</a> to find a specific printcap option and
its effects.</p>
<div class="SECT1">
<h1 class="SECT1"><a name="PRINTCAPPARSE">12.1. The
Printcap Parsing Rules</a></h1>
<p>Options used:</p>
<ul>
<li>
<p><tt class="LITERAL">client</tt> FLAG <i class=
"EMPHASIS">printcap entry valid only for client
programs</i></p>
</li>
<li>
<p><tt class="LITERAL">oh=</tt> <i class=
"EMPHASIS">hosts where printcap entry valid</i></p>
</li>
<li>
<p><tt class="LITERAL">server</tt> <i class=
"EMPHASIS">printcap entry valid only for lpd
server</i></p>
</li>
<li>
<p><tt class="LITERAL">tc</tt> <i class="EMPHASIS">add
named printcap entry contents</i></p>
</li>
</ul>
<br>
<br>
<p>In this section, we will discuss the remaining tricky
parts of the <b class="APPLICATION">LPRng</b> printcap
database: combined client and server printcaps, host
specific printcap entries, and the <tt class=
"LITERAL">tc</tt> <i class="EMPHASIS">include</i>
facility.</p>
<p>The following is a complete description of how a
printcap file is processed:</p>
<ol type="1">
<li>
<p>When processing a printcap file, the <b class=
"APPLICATION">LPRng</b> software reads and parses each
entry individually. Leading whitespace is removed.
Lines starting with <tt class="LITERAL">#</tt> and
blank lines are ignored.</p>
</li>
<li>
<p>Lines ending with <tt class="LITERAL">\</tt> will
have the <tt class="LITERAL">\</tt> discarded, and all
lines of a printcap entry are joined by removing the
line separators (<tt class="LITERAL">\n</tt>) and
replacing them with a space.</p>
</li>
<li>
<p>The printcap entry is parsed, and the printcap name,
aliases, and options are determined. Colons <tt class=
"LITERAL">:</tt> act as option separators, and leading
and trailing whitespaces are removed.</p>
</li>
<li>
<p>Options are sorted and except for the <tt class=
"LITERAL">tc=...</tt> option only the last option
setting is retained.</p>
</li>
<li>
<p>If an option value requires a colon, then the <tt
class="LITERAL">\:</tt> or <tt class=
"LITERAL">\072</tt>, the same escaped character value
as used in the C, Perl, tcl, and other programming
languages, can be used.</p>
</li>
<li>
<p>Client programs will discard a printcap entry with a
<tt class="LITERAL">server</tt> option and server
programs will discard a printcap entry with a <tt
class="LITERAL">client</tt> options.</p>
</li>
<li>
<p>The <tt class="LITERAL">oh</tt> (<i class=
"EMPHASIS">o</i>n this <i class="EMPHASIS">h</i>ost)
option specifies a list of IP addresses and mask pairs
or glob strings which are used to determine if this
printcap entry is valid for this host (see discussion
below).</p>
</li>
<li>
<p>After the above processing, if there is an existing
termcap entry with the same name, the two sets of
options are combined, with the last option setting
retained except for the <tt class="LITERAL">tc</tt>
entries which are combined.</p>
</li>
<li>
<p>When a printcap entry is actually used, the printcap
entries listed by the <tt class="LITERAL">tc</tt>
include option are extracted and combined in order.
This allows include entries to appear after the
referring printcap entry. Then printcap options will be
combined with the included ones. This has the effect
that the options specified in the printcap entry will
override the ones from the <tt class="LITERAL">tc</tt>
included entries.</p>
</li>
<li>
<p>Finally, each string printcap option with a <i
class="EMPHASIS">%X</i> value has <i class=
"EMPHASIS">%X</i> replaced by the following values.
Unspecified values will not be modified.</p>
<div class="INFORMALTABLE">
<a name="AEN5361"></a>
<table border="1" class="CALSTABLE">
<thead>
<tr>
<th align="LEFT" valign="TOP">Key</th>
<th align="LEFT" valign="TOP">Value</th>
<th align="LEFT" valign="TOP">Purpose</th>
</tr>
</thead>
<tbody>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%P</tt></td>
<td align="LEFT" valign="TOP">printcap entry
primary name</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%Q</tt></td>
<td align="LEFT" valign="TOP">queue
requested</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%h</tt></td>
<td align="LEFT" valign="TOP">short host name
(host)</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%H</tt></td>
<td align="LEFT" valign="TOP">fully qualified
host name (host.dns.whatever)</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%R</tt></td>
<td align="LEFT" valign="TOP">remote printer
(rp value)</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%M</tt></td>
<td align="LEFT" valign="TOP">remote host (rm
value)</td>
<td> </td>
</tr>
<tr>
<td align="LEFT" valign="TOP"><tt class=
"LITERAL">%D</tt></td>
<td align="LEFT" valign="TOP">date in
YYYY-MM-DD format</td>
<td> </td>
</tr>
</tbody>
</table>
</div>
<br>
<br>
</li>
<li>
<p>When parsing multiple printcap files, these are
processed in order, and all of their printcap entries
are combined according to the above procedures. The <tt
class="LITERAL">tc</tt> resolution and <i class=
"EMPHASIS">%X</i> expansion is done after all the files
have been processed.</p>
</li>
</ol>
<br>
<br>
<p>The following examples show how to use the above rules
to your advantage. You can combine both client and server
printcap information in a single file as well as dividing a
printcap entry into several parts. Here is an example:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5402"></a>
<pre class="SCREEN">
# seen by both client and server
lp1:lp=lp@pr1:mx=100
lp1:sd=/usr/local/spool/lp1:mx=0
# seen only by client
lp2:lp=lp@pr2:client
# seen only by server
lp2:lp=/dev/lp:server
</pre>
</div>
<ol type="1">
<li>
<p>Printcap entries with the same name are combined.
The first printcap entry, <tt class="LITERAL">lp1</tt>,
the information is seen by both client and server. The
next printcap entry, with the same name <tt class=
"LITERAL">lp1</tt>, will be combined with the first
one. The order of options is important - the entries
are scanned in order and an option will have the last
value set. Thus, after having read both the <tt class=
"LITERAL">lp1</tt> printcap entries, both client and
server will have:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5410"></a>
<pre class="SCREEN">
lp1:lp=lp@pr1
:mx=0
:sd=/usr/local/spool/lp1
</pre>
</div>
<br>
<br>
</li>
<li>
<p>The <tt class="LITERAL">lp2</tt> has a client and
server version. This is recommended when complex
printcaps on multiple hosts and servers are used. Thus,
the <b class="APPLICATION">LPRng</b> clients will
see:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5416"></a>
<pre class="SCREEN">
lp1
:lp=lp@pr1
:mx=0
:sd=/usr/local/spool/lp1
lp2
:client
:lp=lp@pr2
</pre>
</div>
and the server will see:
<div class="INFORMALEXAMPLE">
<a name="AEN5418"></a>
<pre class="SCREEN">
lp1
:lp=lp@pr1
:mx=0
:sd=/usr/local/spool/lp1
lp2
:lp=/dev/lp
:server
</pre>
</div>
<br>
<br>
</li>
</ol>
<br>
<br>
<p>If you have multiple printers of the same type whose
configuration is almost identical, then you can define a
set of <i class="EMPHASIS">tc</i> only printcap entries
containing common information and use the <tt class=
"LITERAL">tc</tt> include facility.</p>
<p>Printcap entry names may start with period (<tt class=
"LITERAL">.</tt>), question mark (<tt class=
"LITERAL">?</tt>), or exclamation mark (<tt class=
"LITERAL">!</tt>), followed by one or more alphanumeric ,
underscore (<tt class="LITERAL">_</tt>) or hyphen (<tt
class="LITERAL">-</tt>) characters. Queue or printer names
start with an alphanumeric character. Printcap entries
whose names do not start with an alphanumeric character can
only be used as targets of the <tt class="LITERAL">tc</tt>
include facility. For example:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5430"></a>
<pre class="SCREEN">
.hp:
:sd=/usr/local/spool/%P
:mx=0
hp1:tc=.hp,.filter
:lp=lp@10.0.0.1
hp2:tc=.hp,.filter
:lp=lp@10.0.0.2
.filter
:filter=/usr/local/libexec/filters/ifhp
</pre>
</div>
<ol type="1">
<li>
<p>The <tt class="FILENAME">.hp</tt> and <tt class=
"FILENAME">.filter</tt> printcap entities are not spool
queue definitions. After <tt class="LITERAL">tc</tt>
include processing is completed, the printcap
information would resemble:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5438"></a>
<pre class="SCREEN">
hp1
:lp=lp@10.0.0.1
:filter=/usr/local/libexec/filters/ifhp
:mx=0
:sd=/usr/local/spool/%P
hp2
:lp=lp@10.0.0.2
:filter=/usr/local/libexec/filters/ifhp
:mx=0
:sd=/usr/local/spool/%P
</pre>
</div>
<br>
<br>
</li>
<li>
<p>The <tt class="LITERAL">%X</tt> processing will
replace <tt class="LITERAL">%P</tt> with the printcap
name, so we would have:</p>
<div class="INFORMALEXAMPLE">
<a name="AEN5444"></a>
<pre class="SCREEN">
hp1
:lp=lp@10.0.0.1
:filter=/usr/local/libexec/filters/ifhp
:mx=0
:sd=/usr/local/spool/hp1
hp2
:lp=lp@10.0.0.2
:filter=/usr/local/libexec/filters/ifhp
:mx=0
:sd=/usr/local/spool/hp2
</pre>
</div>
<br>
<br>
</li>
</ol>
<br>
<br>
</div>
</div>
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