path: root/en_US.ISO_8859-1/books/handbook/printing/chapter.sgml

    <chapter id="printing">
      <title>Printing</title>
      
      <para><emphasis>Contributed by &a.kelly;<!-- <br> -->30 September
	  1995</emphasis></para>
      
      <para>In order to use printers with FreeBSD, you will need to set them
	up to work with the Berkeley line printer spooling system, also known
	as the LPD spooling system. It is the standard printer control system
	in FreeBSD. This section introduces the LPD spooling system, often
	simply called LPD.</para>
      
      <para>If you are already familiar with LPD or another printer spooling
	system, you may wish to skip to section <link
	  linkend="printing-intro-setup">Setting up the spooling
	  system</link>.</para>
      
      
      <sect1 id="printing-intro-spooler">
	<title>What the Spooler Does</title>
	
	<para>LPD controls everything about a host's printers. It is
	  responsible for a number of things:</para>
	
	
	  <itemizedlist>
	    
	    <listitem>
	      <para>It controls access to attached printers and printers
		attached to other hosts on the network.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It enables users to submit files to be printed; these
		submissions are known as <emphasis>jobs</emphasis>.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It prevents multiple users from accessing a printer at the
		same time by maintaining a <emphasis>queue</emphasis> for each
		printer.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It can print <emphasis>header pages</emphasis> (also known
		as <emphasis>banner</emphasis> or <emphasis>burst</emphasis>
		pages) so users can easily find jobs they have printed in a
		stack of printouts.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It takes care of communications parameters for printers
		connected on serial ports.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It can send jobs over the network to another LPD spooler
		on another host.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It can run special filters to format jobs to be printed
		for various printer languages or printer capabilities.</para>
	    </listitem>
	    
	    <listitem>
	      <para>It can account for printer usage.</para>
	    </listitem>
	    
	  </itemizedlist>
	
	
	<para>Through a configuration file, and by providing the special
	  filter programs, you can enable the LPD system to do all or some
	  subset of the above for a great variety of printer hardware.</para>
	
      </sect1>
      
      <sect1 id="printing-intro-why">
	<title>Why You Should Use the Spooler</title>
	
	<para>If you are the sole user of your system, you may be wondering
	  why you should bother with the spooler when you do not need access
	  control, header pages, or printer accounting. While it is possible
	  to enable direct access to a printer, you should use the spooler
	  anyway since</para>
	
	
	  <itemizedlist>
	    
	    <listitem>
	      <para>LPD prints jobs in the background; you do not have to wait
		for data to be copied to the printer.</para>
	    </listitem>
	    
	    <listitem>
	      <para>LPD can conveniently run a job to be printed through
		filters to add date/time headers or convert a special file
		format (such as a TeX DVI file) into a format the printer will
		understand. You will not have to do these steps manually.</para>
	    </listitem>
	    
	    <listitem>
	      <para>Many free and commercial programs that provide a print
		feature usually expect to talk to the spooler on your system.
		By setting up the spooling system, you will more easily
		support other software you may later add or already
		have.</para>
	    </listitem>
	    
	  </itemizedlist>
	
	
      </sect1>
      
      <sect1 id="printing-intro-setup">
	<title>Setting Up the Spooling System</title>
	
	<para>To use printers with the LPD spooling system, you will need to
	  set up both your printer hardware and the LPD software. This
	  document describes two levels of setup:</para>
	
	
	  <itemizedlist>
	    
	    <listitem>
	      <para>See section <link linkend="printing-simple">Simple
		  Printer Setup</link> to learn how to connect a printer, tell LPD
		how to communicate with it, and print plain text files to the
		printer.</para>
	    </listitem>
	    
	    <listitem>
	      <para>See section <link linkend="printing-advanced">Advanced Printer Setup</link> to find out how to print a
		variety of special file formats, to print header pages, to
		print across a network, to control access to printers, and to
		do printer accounting.</para>
	    </listitem>
	    
	  </itemizedlist>
	
	
      </sect1>
      
      <sect1 id="printing-simple">
	<title>Simple Printer Setup</title>
	
	<para>This section tells how to configure printer hardware and the
	  LPD software to use the printer. It teaches the basics:</para>
	
	
	  <itemizedlist>
	    
	    <listitem>
	      <para>Section <link linkend="printing-hardware">Hardware
		  Setup</link> gives some hints on connecting the printer to a port
		on your computer.</para>
	    </listitem>
	    
	    <listitem>
	      <para>Section <link linkend="printing-software">Software
		  Setup</link> shows how to setup the LPD spooler configuration
		file <filename>/etc/printcap</filename>.</para>
	    </listitem>
	    
	  </itemizedlist>
	
	
	<para>If you are setting up a printer that uses a network protocol to
	  accept data to print instead of a serial or parallel interface, see
	  <link linkend="printing-advanced-network-net-if">Printers
	    With Networked Data Stream Interaces</link>.</para>
	
	<para>Although this section is called &ldquo;Simple Printer Setup,&rdquo; it is
	  actually fairly complex. Getting the printer to work with your
	  computer and the LPD spooler is the hardest part. The advanced
	  options like header pages and accounting are fairly easy once you
	  get the printer working.</para>
	
	
	<sect2 id="printing-hardware">
	  <title>Hardware Setup</title>
	  
	  <para>This section tells about the various ways you can connect a
	    printer to your PC. It talks about the kinds of ports and cables,
	    and also the kernel configuration you may need to enable FreeBSD
	    to speak to the printer.</para>
	  
	  <para>If you have already connected your printer and have
	    successfully printed with it under another operating system, you
	    can probably skip to section <link linkend="printing-software">Software Setup</link>.</para>
	  
	  
	  <sect3 id="printing-ports">
	    <title>Ports and Cables</title>
	    
	    <para>Nearly all printers you can get for a PC today support one
	      or both of the following interfaces:</para>
	    
	    
	      <itemizedlist>
		
		<listitem>
		  <para><emphasis>Serial</emphasis> interfaces use a serial
		    port on your computer to send data to the printer. Serial
		    interfaces are common in the computer industry and cables
		    are readily available and also easy to construct. Serial
		    interfaces sometimes need special cables and might require
		    you to configure somewhat complex communications options.</para>
		</listitem>
		
		<listitem>
		  <para><emphasis>Parallel</emphasis> interfaces use a
		    parallel port on your computer to send data to the
		    printer. Parallel interfaces are common in the PC market.
		    Cables are readily available but more difficult to
		    construct by hand. There are usually no communications
		    options with parallel interfaces, making their
		    configuration exceedingly simple.</para>
		  
		  <para>Parallel interfaces are sometimes known as
		    &ldquo;Centronics&rdquo; interfaces, named after the connector type
		    on the printer.</para>
		</listitem>
		
	      </itemizedlist>
	    
	    
	    <para>In general, serial interfaces are slower than parallel
	      interfaces. Parallel interfaces usually offer just one-way
	      communication (computer to printer) while serial gives you
	      two-way. Many newer parallel ports can also receive data from
	      the printer, but only few printers need to send data back to the
	      computer. And FreeBSD does not support two-way parallel
	      communication yet.</para>
	    
	    <para>Usually, the only time you need two-way communication with
	      the printer is if the printer speaks PostScript. PostScript
	      printers can be very verbose. In fact, PostScript jobs are
	      actually programs sent to the printer; they need not produce
	      paper at all and may return results directly to the computer.
	      PostScript also uses two-way communication to tell the computer
	      about problems, such as errors in the PostScript program or
	      paper jams. Your users may be appreciative of such information.
	      Furthermore, the best way to do effective accounting with a
	      PostScript printer requires two-way communication: you ask the
	      printer for its page count (how many pages it has printed in its
	      lifetime), then send the user's job, then ask again for its page
	      count. Subtract the two values and you know how much paper to
	      charge the user.</para>
	    
	    <para>So, which interface should you use?</para>
	    
	    
	      <itemizedlist>
		
		<listitem>
		  <para>If you need two-way communication, use a serial port.
		    FreeBSD does not yet support two-way communication over a
		    parallel port.</para>
		</listitem>
		
		<listitem>
		  <para>If you do not need two-way communication and can pick
		    parallel or serial, prefer the parallel interface. It
		    keeps a serial port free for other peripherals&mdash;such as a
		    terminal or a modem&mdash;and is faster most of the time. It
		    is also easier to configure.</para>
		</listitem>
		
		<listitem>
		  <para>Finally, use whatever works.</para>
		</listitem>
		
	      </itemizedlist>
	    
	    
	  </sect3>
	  
	  <sect3 id="printing-parallel">
	    <title>Parallel Ports</title>
	    
	    <para>To hook up a printer using a parallel interface, connect
	      the Centronics cable between the printer and the computer. The
	      instructions that came with the printer, the computer, or both
	      should give you complete guidance.</para>
	    
	    <para>Remember which parallel port you used on the computer. The
	      first parallel port is <filename>/dev/lpt0</filename> to FreeBSD; the second is
	      <filename>/dev/lpt1</filename>, and so on.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-serial">
	    <title>Serial Ports</title>
	    
	    <para>To hook up a printer using a serial interface, connect the
	      proper serial cable between the printer and the computer. The
	      instructions that came with the printer, the computer, or both
	      should give you complete guidance.</para>
	    
	    <para>If you are unsure what the &ldquo;proper serial cable&rdquo; is, you
	      may wish to try one of the following alternatives:</para>
	      <itemizedlist>
		
		<listitem>
		  <para>A <emphasis>modem</emphasis> cable connects each pin
		    of the connector on one end of the cable straight through
		    to its corresponding pin of the connector on the other
		    end. This type of cable is also known as a &ldquo;DTE-to-DCE&rdquo;
		    cable.</para>
		</listitem>
		
		<listitem>
		  <para>A <emphasis>null-modem</emphasis> cable connects some
		    pins straight through, swaps others (send data to receive
		    data, for example), and shorts some internally in each
		    connector hood. This type of cable is also known as a
		    &ldquo;DTE-to-DTE&rdquo; cable.</para>
		</listitem>
		
		<listitem>
		  <para>A <emphasis>serial printer</emphasis> cable, required
		    for some unusual printers, is like the null modem cable,
		    but sends some signals to their counterparts instead of
		    being internally shorted.</para>
		</listitem>
		
	      </itemizedlist>
	    
	    <para>You should also set up the communications parameters for the
	      printer, usually through front-panel controls or DIP switches on
	      the printer. Choose the highest bps (bits per second, sometimes
	      <emphasis>baud rate</emphasis>) rate that both your computer and
	      the printer can support. Choose 7 or 8 data bits; none, even,
	      or odd parity; and 1 or 2 stop bits. Also choose a flow control
	      protocol: either none, or XON/XOFF (also known as
	      &ldquo;in-band&rdquo; or &ldquo;software&rdquo;)
	      flow control. Remember these settings for the software
	      configuration that follows.</para>
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-software">
	  <title>Software Setup</title>
	  
	  <para>This section describes the software setup necessary to print
	    with the LPD spooling system in FreeBSD.</para>
	  
	  <para>Here is an outline of the steps involved:</para>
	  
	    <procedure>
	      
	      <step>
		<para>Configure your kernel, if necessary, for the port you
		  are using for the printer; section <link
		    linkend="printing-kernel">Kernel Configuration</link>
		  tells you what you need to do.</para>
	      </step>
	      
	      <step>
		<para>Set the communications mode for the parallel port, if
		  you are using a parallel port; section <link
		    linkend="printing-parallel-port-mode">Setting the
		    Communication Mode for the Parallel Port</link> gives details.</para>
	      </step>
	      
	      <step>
		<para>Test if the operating system can send data to the
		  printer. Section <link linkend="printing-testing">Checking Printer Communications</link> gives some
		  suggestions on how to do this.</para>
	      </step>
	      
	      <step>
		<para>Set up LPD for the printer by modifying the file
		  <filename>/etc/printcap</filename>. Section <link
		    linkend="printing-printcap">The /etc/printcap
		    File</link> shows you how.</para>
	      </step>
	      
	    </procedure>
	  
	  <sect3 id="printing-kernel">
	    <title>Kernel Configuration</title>
	    
	    <para>The operating system kernel is compiled to work with a
	      specific set of devices. The serial or parallel interface for
	      your printer is a part of that set. Therefore, it might be
	      necessary to add support for an additional serial or parallel
	      port if your kernel is not already configured for one.</para>
	    
	    <para>To find out if the kernel you are currently using supports a
	      serial interface, type:</para>
	      
	      <informalexample>
		<screen>&prompt.root; <userinput>dmesg | grep sio<replaceable>N</replaceable></userinput></screen>
	      </informalexample>

	    <para>Where <replaceable>N</replaceable> is the
	      number of the serial port, starting from zero. If you see
	      output similar to the following:</para>
	      
	      <informalexample>
		<screen>sio2 at 0x3e8-0x3ef irq 5 on isa
sio2: type 16550A</screen>
	      </informalexample>

	    <para>then the kernel supports the port.</para>
	    
	    <para>To find out if the kernel supports a parallel interface,
	      type:</para>
	      
	      <informalexample>
		<screen>&prompt.root; <userinput>dmesg | grep lpt<replaceable>N</replaceable></userinput></screen>
	      </informalexample>

	    <para>Where <replaceable>N</replaceable> is the
	      number of the parallel port, starting from zero. If you see
	      output similar to the following
	      
	      <informalexample>
		<screen>lpt0 at 0x378-0x37f on isa</screen>
	      </informalexample> then the kernel supports the port.</para>
	    
	    <para>You might have to reconfigure your kernel in order for the
	      operating system to recognize and use the parallel or serial
	      port you are using for the printer.</para>
	    
	    <para>To add support for a serial port, see the section on kernel
	      configuration. To add support for a parallel port, see that
	      section <emphasis>and</emphasis> the section that
	      follows.</para>
	    
	    
	    <sect4 id="printing-dev-ports">
	      <title>Adding <filename>/dev</filename> Entries for the Ports</title>
	      
	      <para>Even though the kernel may support communication along a
		serial or parallel port, you will still need a software
		interface through which programs running on the system can
		send and receive data. That is what entries in the
		<filename>/dev</filename> directory are for.</para>
	      
	      <para><emphasis>To add a <filename>/dev</filename>
		  entry for a port:</emphasis></para>
	      
		<procedure>
		  
		  <step>
		    <para>Become root with the  <citerefentry>
			<refentrytitle>su</refentrytitle></citerefentry>
		      command. Enter the root password when prompted.</para>
		  </step>
		  
		  <step>
		    <para>Change to the <filename>/dev</filename> directory:</para>
		    
		      <informalexample>
			<screen>&prompt.root; cd /dev</screen>
		      </informalexample>
		  </step>
		  
		  <step>
		    <para>Type:</para>
		    
		      <informalexample>
			<screen>&prompt.root; <userinput>./MAKEDEV <replaceable>port</replaceable></userinput></screen>
		      </informalexample>

		  <para>Where <replaceable>port</replaceable> is the device entry for the
		      port you want to make. Use <literal>lpt0</literal> for the first parallel port,
		      <literal>lpt1</literal> for the second, and
		      so on; use <literal>ttyd0</literal> for the
		      first serial port, <literal>ttyd1</literal>
		      for the second, and so on.</para>
		  </step>
		  
		  <step>
		    <para>Type:</para>
		    
		      <informalexample>
			<screen>&prompt.root; <userinput>ls -l <replaceable>port</replaceable></userinput></screen>
		      </informalexample>

		  <para>to make sure the device entry got
		      created.</para>
		  </step>
		  
		</procedure>
	      
	    </sect4>
	    
	    <sect4 id="printing-parallel-port-mode">
	      <title>Setting the Communication Mode for the Parallel Port</title>
	      
	      <para>When you are using the parallel interface, you can choose
		whether FreeBSD should use interrupt-driven or polled
		communication with the printer.</para>
	      
	      
		<itemizedlist>
		  
		  <listitem>
		    <para>The <emphasis>interrupt-driven</emphasis> method is
		      the default with the GENERIC kernel. With this method,
		      the operating system uses an IRQ line to determine when
		      the printer is ready for data.</para>
		  </listitem>
		  
		  <listitem>
		    <para>The <emphasis>polled</emphasis> method directs the
		      operating system to repeatedly ask the printer if it is
		      ready for more data. When it responds ready, the kernel
		      sends more data.</para>
		  </listitem>
		  
		</itemizedlist>
	      
	      
	      <para>The interrupt-driven method is somewhat faster but uses up
		a precious IRQ line. You should use whichever one
		works.</para>
	      
	      <para>You can set the communications mode in two ways: by
		configuring the kernel or by using the  <citerefentry>
		  <refentrytitle>lptcontrol</refentrytitle></citerefentry> program.</para>
	      
	      <para><emphasis>To set the communications mode by
		  configuring the kernel:</emphasis></para>

		<procedure>
		  
		  <step>
		    <para>Edit your kernel configuration file. Look for or
		      add an <literal>lpt0</literal> entry. If you
		      are setting up the second parallel port, use <literal>lpt1</literal> instead. Use <literal>lpt2</literal> for the third port, and so
		      on.</para>
		      <itemizedlist>
			
			<listitem>
			  <para>If you want interrupt-driven mode, add the
			    <literal>irq</literal> specifier:</para>
			  
			    <programlisting>
device lpt0 at isa? port? tty irq <replaceable>N</replaceable> vector lptintr</programlisting>

		      <para>Where <replaceable>N</replaceable> is the IRQ number for your
			    computer's parallel port.</para>
			</listitem>
			
			<listitem>
			  <para>If you want polled mode, do not add the
			    <literal>irq</literal> specifier:</para>
			  
			    <programlisting>
device lpt0 at isa? port? tty vector lptintr</programlisting>
			</listitem>
			
		      </itemizedlist>

		  </step>
		  
		  <step>
		    <para>Save the file. Then configure, build, and install
		      the kernel, then reboot. See <link
			linkend="kernelconfig">kernel configuration</link>
		      for more details.</para>
		  </step>
		  
		</procedure>
	      
	      <para><emphasis>To set the communications mode
		  with</emphasis> <citerefentry>
		  <refentrytitle>lptcontrol</refentrytitle></citerefentry>:</para>
	      
		<procedure>
		  
		  <step>
		    <para>Type:</para>
		    
		      <informalexample>
			<screen>&prompt.root; <userinput>lptcontrol -i -u <replaceable>N</replaceable></userinput></screen>
		      </informalexample>

		  <para>to set interrupt-driven mode for
		      <literal>lpt<replaceable>N</replaceable></literal>.</para>
		  </step>
		  
		  <step>
		    <para>Type:</para>
		    
		      <informalexample>
			<screen>&prompt.root; <userinput>lptcontrol -p -u <replaceable>N</replaceable></userinput></screen>
		      </informalexample>

		  <para>to set polled-mode for <literal>lpt<replaceable>N</replaceable></literal>.</para>
		  </step>
		  
		</procedure>

	      <para>You could put these commands in your
		<filename>/etc/rc.local</filename> file to set the mode each
		time your system boots. See  <citerefentry><refentrytitle>lptcontrol</refentrytitle><manvolnum>8</manvolnum></citerefentry> for more information.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-testing">
	      <title>Checking Printer Communications</title>
	      
	      <para>Before proceeding to configure the spooling system, you
		should make sure the operating system can successfully send
		data to your printer. It is a lot easier to debug printer
		communication and the spooling system separately.</para>
	      
	      <para>To test the printer, we will send some text to it. For
		printers that can immediately print characters sent to them,
		the program  <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry> is perfect: it generates all 96 printable ASCII characters in 96 lines.</para>
	      
	      <para>For a PostScript (or other language-based) printer, we
		will need a more sophisticated test. A small PostScript
		program, such as the following, will suffice:</para>

		<programlisting>
%!PS
100 100 moveto 300 300 lineto stroke
310 310 moveto /Helvetica findfont 12 scalefont setfont
(Is this thing working?) show
showpage</programlisting>

	      
	      <note>
		<para>When this document refers to a printer language, I am
		  assuming a language like PostScript, and not Hewlett
		  Packard's PCL. Although PCL has great functionality, you can
		  intermingle plain text with its escape sequences.
		  PostScript cannot directly print plain text, and that is the
		  kind of printer language for which we must make special
		  accommodations.</para>
	      </note>
	      
	      <sect5 id="printing-checking-parallel">
		<title>Checking a Parallel Printer</title>
		
		<para>This section tells you how to check if FreeBSD can
		  communicate with a printer connected to a parallel
		  port.</para>
		
		<para><emphasis>To test a printer on a parallel
		    port:</emphasis></para>
		
		  <procedure>
		    
		    <step>
		      <para>Become root with  <citerefentry>
			  <refentrytitle>su</refentrytitle></citerefentry>.</para>
		    </step>
		    
		    <step>
		      <para>Send data to the printer.</para>
			<itemizedlist>
			  
			  <listitem>
			    <para>If the printer can print plain text, then
			      use <citerefentry>
				<refentrytitle>lptest</refentrytitle></citerefentry>. Type:</para>
			    
			      <informalexample>
				<screen>&prompt.root; <userinput>lptest &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>
			      </informalexample>

			<para>Where <replaceable>N</replaceable> is the number of the
			      parallel port, starting from zero.</para>
			  </listitem>
			  
			  <listitem>
			    <para>If the printer understands PostScript or
			      other printer language, then send a small
			      program to the printer. Type:</para>
			    
			      <informalexample>
				<screen>&prompt.root; <userinput>cat &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>
			      </informalexample>

			<para>Then, line by line, type the
			      program <emphasis>carefully</emphasis> as you
			      cannot edit a line once you have pressed RETURN
			      or ENTER. When you have finished entering the
			      program, press CONTROL+D, or whatever your end
			      of file key is.</para>
			    
			    <para>Alternatively, you can put the program in a
			      file and type:</para>
			    
			      <informalexample>
				<screen>&prompt.root; <userinput>cat <replaceable>file</replaceable> &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>
			      </informalexample>

			<para>Where <replaceable>file</replaceable> is the name of the
			      file containing the program you want to send to
			      the printer.</para>
			  </listitem>
			  
			</itemizedlist>

		    </step>
		    
		  </procedure>
		
		<para>You should see something print. Do not worry if the
		  text does not look right; we will fix such things
		  later.</para>
		
	      </sect5>
	      
	      <sect5 id="printing-checking-serial">
		<title>Checking a Serial Printer</title>
		
		<para>This section tells you how to check if FreeBSD can
		  communicate with a printer on a serial port.</para>
		
		<para><emphasis>To test a printer on a serial
		    port:</emphasis></para>
		
		  <procedure>
		    
		    <step>
		      <para>Become root with  <citerefentry>
			  <refentrytitle>su</refentrytitle></citerefentry>.</para>
		    </step>
		    
		    <step>
		      <para>Edit the file <filename>/etc/remote</filename>.
			Add the following entry:</para>
		      
			<programlisting>
printer:dv=/dev/<replaceable>port</replaceable>:br#<replaceable>bps-rate</replaceable>:pa=<replaceable>parity</replaceable></programlisting>

		    <para>Where <replaceable>port</replaceable> is the device entry for the
			serial port (<literal>ttyd0</literal>,
			<literal>ttyd1</literal>, etc.), <replaceable>bps-rate</replaceable> is the bits-per-second
			rate at which the printer communicates, and
			<replaceable>parity</replaceable> is the parity required by
			the printer (either <literal>even</literal>, <literal>odd</literal>, <literal>none</literal>, or <literal>zero</literal>).</para>
		      
		      <para>Here is a sample entry for a printer connected via
			a serial line to the third serial port at 19200 bps
			with no parity:</para>
		      
			<programlisting>
printer:dv=/dev/ttyd2:br#19200:pa=none</programlisting>
		    </step>
		    
		    <step>
		      <para>Connect to the printer with  <citerefentry>
			  <refentrytitle>tip</refentrytitle></citerefentry>. Type:</para>
			<informalexample>
			  <screen>&prompt.root; <userinput>tip printer</userinput></screen>
			</informalexample>

		    <para>If this step does not work, edit
			the file <filename>/etc/remote</filename> again and
			try using
			<filename>/dev/cuaa<replaceable>N</replaceable></filename> instead of <filename>/dev/ttyd<replaceable>N</replaceable></filename>.</para>
		    </step>
		    
		    <step>
		      <para>Send data to the printer.</para>
			<itemizedlist>
			  
			  <listitem>
			    <para>If the printer can print plain text, then
			      use  <citerefentry>
				<refentrytitle>lptest</refentrytitle></citerefentry>. Type:</para>
			    
			      <informalexample>
				<screen><prompt>~</prompt><userinput>$lptest</userinput></screen>
			      </informalexample>
			  </listitem>
			  
			  <listitem>
			    <para>If the printer understands PostScript or
			      other printer language, then send a small
			      program to the printer. Type the program, line
			      by line, <emphasis>very carefully</emphasis> as
			      backspacing or other editing keys may be
			      significant to the printer. You may also need to
			      type a special end-of-file key for the printer
			      so it knows it received the whole program. For
			      PostScript printers, press CONTROL+D.</para>
			    
			    <para>Alternatively, you can put the program in a
			      file and type:</para>
			    
			      <informalexample>
				<screen><prompt>~</prompt><userinput>&gt;<replaceable>file</replaceable></userinput></screen>
			      </informalexample>

			<para>Where <replaceable>file</replaceable> is the name of the
			      file containing the program. After
			      <citerefentry>
				<refentrytitle>tip</refentrytitle></citerefentry> sends the file, press any required end-of-file key.</para>
			  </listitem>
			  
			</itemizedlist>

		    </step>
		    
		  </procedure>
		
		<para>You should see something print. Do not worry if the
		  text does not look right; we will fix that later.</para>
		
	      </sect5>
	    </sect4>
	  </sect3>
	  
	  <sect3 id="printing-printcap">
	    <title>Enabling the Spooler: The
	      <filename>/etc/printcap</filename> File</title>
	    
	    <para>At this point, your printer should be hooked up, your
	      kernel configured to communicate with it (if necessary), and you
	      have been able to send some simple data to the printer. Now, we
	      are ready to configure LPD to control access to your
	      printer.</para>
	    
	    <para>You configure LPD by editing the file
	      <filename>/etc/printcap</filename>. The LPD spooling system
	      reads this file each time the spooler is used, so updates to the
	      file take immediate effect.</para>
	    
	    <para>The format of the  <citerefentry>
		<refentrytitle>printcap</refentrytitle></citerefentry> file is straightforward. Use your favorite text editor to make changes to <filename>/etc/printcap</filename>. The format is identical to other capability files like <filename>/usr/share/misc/termcap</filename> and <filename>/etc/remote</filename>. For complete information about the format, see the  <citerefentry><refentrytitle>cgetent</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
	    
	    <para>The simple spooler configuration consists of the following
	      steps:</para>
	      
	      <procedure>
		
		<step>
		  <para>Pick a name (and a few convenient aliases) for the
		    printer, and put them in the
		    <filename>/etc/printcap</filename> file; see <link
		      linkend="printing-naming">Naming the Printer</link>.</para>
		</step>
		
		<step>
		  <para>Turn off header pages (which are on by default) by
		    inserting the <literal>sh</literal> capability;
		    see <link linkend="printing-no-header-pages">Suppressing Header   Pages</link>.</para>
		</step>
		
		<step>
		  <para>Make a spooling directory, and specify its location
		    with the <literal>sd</literal> capability; see
		    <link linkend="printing-spooldir">Making the Spooling   Directory</link>.</para>
		</step>
		
		<step>
		  <para>Set the <filename>/dev</filename> entry to use for the
		    printer, and note it in <filename>/etc/printcap</filename>
		    with the <literal>lp</literal> capability; see
		    <link
		      linkend="printing-device">Identifying the Printer
		      Device</link>. Also, if the printer is on a serial port, set
		    up the communication parameters with the
		  <literal>fs</literal>, <literal>fc</literal>,
		  <literal>xs</literal>, and <literal>xc</literal> capabilities; see <link
		      linkend="printing-commparam">Configuring Spooler
		      Communications Parameters</link>.</para>
		</step>
		
		<step>
		  <para>Install a plain text input filter; see <link
		      linkend="printing-textfilter">Installing the Text
		      Filter</link></para>
		</step>
		
		<step>
		  <para>Test the setup by printing something with the
		    <citerefentry>
		      <refentrytitle>lpr</refentrytitle></citerefentry>
		    command; see <link linkend="printing-trying">Trying
		      It Out</link> and <link linkend="printing-troubleshooting">Troubleshooting</link>.</para>
		</step>
		
	      </procedure>

	    <note>
	      <para>Language-based printers, such as PostScript printers,
		cannot directly print plain text. The simple setup outlined
		above and described in the following sections assumes that if
		you are installing such a printer you will print only files
		that the printer can understand.</para>
	    </note>
	    
	    <para>Users often expect that they can print plain text to any of
	      the printers installed on your system. Programs that interface
	      to LPD to do their printing usually make the same assumption.
	      If you are installing such a printer and want to be able to
	      print jobs in the printer language <emphasis>and</emphasis>
	      print plain text jobs, you are strongly urged to add an
	      additional step to the simple setup outlined above: install an
	      automatic plain-text-to-PostScript (or other printer language)
	      conversion program. Section <link
		linkend="printing-advanced-if-conversion">Accommodating
		Plain Text Jobs on PostScript Printers</link> tells how to do
	      this.</para>
	    
	    
	    <sect4 id="printing-naming">
	      <title>Naming the Printer</title>
	      
	      <para>The first (easy) step is to pick a name for your printer.
		It really does not matter whether you choose functional or
		whimsical names since you can also provide a number aliases
		for the printer.</para>
	      
	      <para>At least one of the printers specified in the
		<filename>/etc/printcap</filename> should have the alias
		<literal>lp</literal>. This is the default
		printer's name. If users do not have the <envar>PRINTER</envar> environment
		variable nor specify a printer name on the command line of any
		of the LPD commands, then <literal>lp</literal>
		will be the default printer they get to use.</para>
	      
	      <para>Also, it is common practice to make the last alias for a
		printer be a full description of the printer, including make
		and model.</para>
	      
	      <para>Once you have picked a name and some common aliases, put
		them in the <filename>/etc/printcap</filename> file. The name
		of the printer should start in the leftmost column. Separate
		each alias with a vertical bar and put a colon after the last
		alias.</para>
	      
	      <para>In the following example, we start with a skeletal
		<filename>/etc/printcap</filename> that defines two printers
		(a Diablo 630 line printer and a Panasonic KX-P4455 PostScript
		laser printer):</para>

		<programlisting>
#
#  /etc/printcap for host rose
#
rattan|line|diablo|lp|Diablo 630 Line Printer:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:</programlisting>

	      <para>In this example, the first printer is named
		<literal>rattan</literal> and has as aliases
		<literal>line</literal>, <literal>diablo</literal>,
		<literal>lp</literal>, and <literal>Diablo 630
		  Line Printer</literal>. Since it has the alias <literal>lp</literal>, it is also the default printer. The
		second is named <literal>bamboo</literal>, and has
		as aliases <literal>ps</literal>,
		<literal>PS</literal>, <literal>S</literal>,
		<literal>panasonic</literal>, and <literal>Panasonic KX-P4455 PostScript
		  v51.4</literal>.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-no-header-pages">
	      <title>Suppressing Header Pages</title>
	      
	      <para>The LPD spooling system will by default print a
		<emphasis>header page</emphasis> for each job. The header
		page contains the user name who requested the job, the host
		from which the job came, and the name of the job, in nice
		large letters. Unfortunately, all this extra text gets in the
		way of debugging the simple printer setup, so we will suppress
		header pages.</para>
	      
	      <para>To suppress header pages, add the <literal>sh</literal> capability to the entry for the
		printer in <filename>/etc/printcap</filename>. Here is the
		example <filename>/etc/printcap</filename> with <literal>sh</literal> added:</para>
		
		<programlisting>
#
#  /etc/printcap for host rose - no header pages anywhere
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:</programlisting>

	      <para>Note how we used the correct format: the
		first line starts in the leftmost column, and subsequent lines
		are indented with a single TAB. Every line in an entry except
		the last ends in a backslash character.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-spooldir">
	      <title>Making the Spooling Directory</title>
	      
	      <para>The next step in the simple spooler setup is to make a
		<emphasis>spooling directory</emphasis>, a directory where
		print jobs reside until they are printed, and where a number
		of other spooler support files live.</para>
	      
	      <para>Because of the variable nature of spooling directories, it
		is customary to put these directories under
		<filename>/var/spool</filename>. It is not necessary to
		backup the contents of spooling directories, either.
		Recreating them is as simple as running  <citerefentry>
		  <refentrytitle>mkdir</refentrytitle></citerefentry>.</para>
	      
	      <para>It is also customary to make the directory with a name
		that is identical to the name of the printer, as shown below:</para>
		
		<informalexample>
		  <screen>&prompt.root; <userinput>mkdir /var/spool/<replaceable>printer-name</replaceable></userinput></screen>
		</informalexample>

	      <para>However, if you have a lot of printers on
		your network, you might want to put the spooling directories
		under a single directory that you reserve just for printing
		with LPD. We will do this for our two example printers
		<literal>rattan</literal> and <literal>bamboo</literal>:</para>
		
		<informalexample>
		  <screen>&prompt.root; <userinput>mkdir /var/spool/lpd</userinput>
&prompt.root; <userinput>mkdir /var/spool/lpd/rattan</userinput>
&prompt.root; <userinput>mkdir /var/spool/lpd/bamboo</userinput></screen>
		</informalexample>

	      <note>
		<para>If you are concerned about the privacy of jobs that
		  users print, you might want to protect the spooling
		  directory so it is not publicly accessible. Spooling
		  directories should be owned and be readable, writable, and
		  searchable by user daemon and group daemon, and no one else.
		  We will do this for our example printers:</para>
		
		
		  <informalexample>
		    <screen>&prompt.root; <userinput>chown daemon.daemon /var/spool/lpd/rattan</userinput>
&prompt.root; <userinput>chown daemon.daemon /var/spool/lpd/bamboo</userinput>
&prompt.root; <userinput>chmod 770 /var/spool/lpd/rattan</userinput>
&prompt.root; <userinput>chmod 770 /var/spool/lpd/bamboo</userinput></screen>
		  </informalexample>
	      </note>
	      
	      <para>Finally, you need to tell LPD about these directories
		using the <filename>/etc/printcap</filename> file. You
		specify the pathname of the spooling directory with the
		<literal>sd</literal> capability:</para>

		<programlisting>
#
#  /etc/printcap for host rose - added spooling directories
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:</programlisting>

	      <para>Note that the name of the printer starts in
		the first column but all other entries describing the printer
		should be indented with a tab and each line escaped with a
		backslash.</para>
	      
	      <para>If you do not specify a spooling directory with <literal>sd</literal>, the spooling system will use
		<filename>/var/spool/lpd</filename> as a default.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-device">
	      <title>Identifying the Printer Device</title>
	      
	      <para>In section <link linkend="printing-dev-ports">Adding   /dev Entries for the Ports</link>, we identified
		which entry in the <filename>/dev</filename> directory FreeBSD
		will use to communicate with the printer. Now, we tell LPD
		that information. When the spooling system has a job to
		print, it will open the specified device on behalf of the
		filter program (which is responsible for passing data to the
		printer).</para>
	      
	      <para>List the <filename>/dev</filename> entry pathname in the
		<filename>/etc/printcap</filename> file using the <literal>lp</literal> capability.</para>
	      
	      <para>In our running example, let us assume that <hostid>rattan</hostid> is on the first parallel port,
		and <hostid>bamboo</hostid> is on a sixth serial
		port; here are the additions to
		<filename>/etc/printcap</filename>:</para>
		
		<programlisting>
#
#  /etc/printcap for host rose - identified what devices to use
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:\
        :lp=/dev/ttyd5:</programlisting>
	      
	      <para>If you do not specify the <literal>lp</literal>
		capability for a printer in your
		<filename>/etc/printcap</filename> file, LPD uses
		<filename>/dev/lp</filename> as a default.
		<filename>/dev/lp</filename> currently does not exist in
		FreeBSD.</para>
	      
	      <para>If the printer you are installing is connected to a
		parallel port, skip to the section <link
		  linkend="printing-textfilter">Installing        the
		  Text Filter</link>. Otherwise, be sure to follow the
		instructions in the next section.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-commparam">
	      <title>Configuring Spooler Communication Parameters</title>
	      
	      <para>For printers on serial ports, LPD can set up the bps
		rate, parity, and other serial communication parameters on
		behalf of the filter program that sends data to the printer.
		This is advantageous since:</para>
		
		<itemizedlist>
		  
		  <listitem>
		    <para>It lets you try different communication parameters
		      by simply editing the <filename>/etc/printcap</filename>
		      file; you do not have to recompile the filter program.</para>
		  </listitem>
		  
		  <listitem>
		    <para>It enables the spooling system to use the same
		      filter program for multiple printers which may have
		      different serial communication settings.</para>
		  </listitem>
		  
		</itemizedlist>

	      
	      <para>The following <filename>/etc/printcap</filename>
		capabilities control serial communication parameters of the
		device listed in the <literal>lp</literal>
		capability:</para>

		<variablelist>
		  <varlistentry><term><literal>br#<replaceable>bps-rate</replaceable></literal></term>
		    <listitem>
		      <para>Sets the communications speed of the device to
			<replaceable>bps-rate</replaceable>, where
			<replaceable>bps-rate</replaceable> can be 50, 75,
			110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
			9600, 19200, or 38400 bits-per-second.</para>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term><literal>fc#<replaceable>clear-bits</replaceable></literal></term>
		    
		    <listitem>
		      <para>Clears the flag bits
			<replaceable>clear-bits</replaceable> in the
			<replaceable>sgttyb</replaceable> structure after opening
			the device.</para>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term><literal>fs#<replaceable>set-bits</replaceable></literal></term>
		    
		    <listitem>
		      <para>Sets the flag bits
			<replaceable>set-bits</replaceable> in the
			<replaceable>sgttyb</replaceable> structure.</para>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term><literal>xc#<replaceable>clear-bits</replaceable></literal></term>
		    
		    <listitem>
		      <para>Clears local mode bits <replaceable>clear-bits</replaceable> after opening the
			device.</para>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term><literal>xs#<replaceable>set-bits</replaceable></literal></term>
		    
		    <listitem>
		      <para>Sets local mode bits <replaceable>set-bits</replaceable>.</para>
		      
		    </listitem>
		  </varlistentry>
		</variablelist>

	      <para>For more information on the bits for the
		<literal>fc</literal>, <literal>fs</literal>, <literal>xc</literal>,
		and <literal>xs</literal> capabilities, see the
		file
		<filename>/usr/include/sys/ioctl_compat.h</filename>.</para>
	      
	      <para>When LPD opens the device specified by the <literal>lp</literal> capability, it reads the flag bits in
		the <literal>sgttyb</literal> structure; it clears
		any bits in the <literal>fc</literal> capability,
		then sets bits in the <literal>fs</literal>
		capability, then applies the resultant setting. It does the
		same for the local mode bits as well.</para>
	      
	      <para>Let us add to our example printer on the sixth serial
		port. We will set the bps rate to 38400. For the flag bits,
		we will set the TANDEM, ANYP, LITOUT, FLUSHO, and PASS8 flags.
		For the local mode bits, we will set the LITOUT and PASS8
		flags:</para>

		<programlisting>
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:\
        :lp=/dev/ttyd5:fs#0x82000c1:xs#0x820:</programlisting>
	      
	    </sect4>
	    
	    <sect4 id="printing-textfilter">
	      <title>Installing the Text Filter</title>
	      
	      <para>We are now ready to tell LPD what text filter to use to
		send jobs to the printer. A <emphasis>text filter</emphasis>,
		also known as an <emphasis>input filter</emphasis>, is a
		program that LPD runs when it has a job to print. When LPD
		runs the text filter for a printer, it sets the filter's
		standard input to the job to print, and its standard output to
		the printer device specified with the <literal>lp</literal> capability. The filter is expected
		to read the job from standard input, perform any necessary
		translation for the printer, and write the results to standard
		output, which will get printed. For more information on the
		text filter, see section <link
		  linkend="printing-advanced-filters">Filters</link>.</para>
	      
	      <para>For our simple printer setup, the text filter can be a
		small shell script that just executes
		<command>/bin/cat</command> to send the job to the printer.
		FreeBSD comes with another filter called <filename>lpf</filename> that handles backspacing and
		underlining for printers that might not deal with such
		character streams well. And, of course, you can use any other
		filter program you want. The filter <command>lpf</command> is described in detail in section
		<link linkend="printing-advanced-lpf">lpf: a
		  Text Filter</link>.</para>
	      
	      <para>First, let us make the shell script
		<filename>/usr/local/libexec/if-simple</filename> be a simple
		text filter. Put the following text into that file with your
		favorite text editor:</para>
		
		<programlisting>
#!/bin/sh
#
# if-simple - Simple text input filter for lpd
# Installed in /usr/local/libexec/if-simple
#
# Simply copies stdin to stdout.  Ignores all filter arguments.

/bin/cat &amp;&amp; exit 0
exit 2</programlisting>
		<para>Make the file executable:</para>
		
		<informalexample>
		  <screen>&prompt.root; <userinput>chmod 555 /usr/local/libexec/if-simple</userinput></screen>
		</informalexample>
	      
	      <para>And then tell LPD to use it by specifying it with the
		<literal>if</literal> capability in
		<filename>/etc/printcap</filename>. We will add it to the two
		printers we have so far in the example
		<filename>/etc/printcap</filename>:</para>
		
		<programlisting>
#
#  /etc/printcap for host rose - added text filter
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\ :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:\
        :if=/usr/local/libexec/if-simple:</programlisting>
	      
	    </sect4>
	    
	    <sect4 id="printing-trying">
	      <title>Trying It Out</title>
	      
	      <para>You have reached the end of the simple LPD setup.
		Unfortunately, congratulations are not quite yet in order,
		since we still have to test the setup and correct any
		problems. To test the setup, try printing something. To
		print with the LPD system, you use the command  <citerefentry>
		  <refentrytitle>lpr</refentrytitle></citerefentry>,
		which submits a job for printing.</para>
	      
	      <para>You can combine  <citerefentry>
		  <refentrytitle>lpr</refentrytitle></citerefentry>
		with the  <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry> program, introduced in section <link linkend="printing-testing">Checking Printer Communications</link> to generate some
		test text.</para>
	      
	      <para><emphasis>To test the simple LPD
		  setup:</emphasis></para>
	      
	      <para>Type:</para>
		
		<informalexample>
		  <screen>&prompt.root; <userinput>lptest 20 5 | lpr -P<replaceable>printer-name</replaceable></userinput></screen>
		</informalexample>

	      <para>Where <replaceable>printer-name</replaceable> is a the name of a printer
		(or an alias) specified in <filename>/etc/printcap</filename>.
		To test the default printer, type  <citerefentry>
		  <refentrytitle>lpr</refentrytitle></citerefentry>
		without any <option>-P</option> argument. Again, if you are
		testing a printer that expects PostScript, send a PostScript
		program in that language instead of using  <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry>. You
		can do so by putting the program in a file and typing <command>lpr <replaceable>file</replaceable></command>.</para>
	      
	      <para>For a PostScript printer, you should get the results of
		the program. If you are using  <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry>, then your results should look like the following:</para>
	      
	      <programlisting>
!"#$%&amp;'()*+,-./01234
"#$%&amp;'()*+,-./012345
#$%&amp;'()*+,-./0123456
$%&amp;'()*+,-./01234567
%&amp;'()*+,-./012345678</programlisting>
	      
	      <para>To further test the printer, try downloading larger
		programs (for language-based printers) or running <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry> with different arguments. For example, <command>lptest 80 60</command> will produce 60 lines of 80 characters each.</para>
	      
	      <para>If the printer did not work, see the next section, <link
		  linkend="printing-troubleshooting">Troubleshooting</link>.</para>
	      
	    </sect4>
	    
	    <sect4 id="printing-troubleshooting">
	      <title>Troubleshooting</title>
	      
	      <para>After performing the simple test with  <citerefentry>
		  <refentrytitle>lptest</refentrytitle></citerefentry>, you
		might have gotten one of the following results instead of the
		correct printout:</para>
	      
		<variablelist>
		  <varlistentry><term>It worked, after awhile; or, it did not
		      eject a full sheet.</term>
		    <listitem>
		      <para>The printer printed the above, but it sat for
			awhile and did nothing. In fact, you might have
			needed to press a PRINT REMAINING or FORM FEED button
			on the printer to get any results to appear.</para>
		      
		      <para>If this is the case, the printer was probably
			waiting to see if there was any more data for your job
			before it printed anything. To fix this problem, you
			can have the text filter send a FORM FEED character
			(or whatever is necessary) to the printer. This is
			usually sufficient to have the printer immediately
			print any text remaining in its internal buffer. It
			is also useful to make sure each print job ends on a
			full sheet, so the next job does not start somewhere
			on the middle of the last page of the previous
			job.</para>
		      
		      <para>The following replacement for the shell script
			<filename>/usr/local/libexec/if-simple</filename>
			prints a form feed after it sends the job to the
			printer:</para>

			<programlisting>
#!/bin/sh
#
# if-simple - Simple text input filter for lpd
# Installed in /usr/local/libexec/if-simple
#
# Simply copies stdin to stdout.  Ignores all filter arguments.
# Writes a form feed character (\f) after printing job.

/bin/cat &amp;&amp; printf "\f" &amp;&amp; exit 0
exit 2</programlisting>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term>It produced the &ldquo;staircase
		      effect.&rdquo;</term>
		    
		    <listitem>
		      <para>You got the following on paper:</para>

			<programlisting>
!"#$%&amp;'()*+,-./01234
			    "#$%&amp;'()*+,-./012345
			                                 #$%&amp;'()*+,-./0123456</programlisting>
		    <para>You have become another victim of
			the <emphasis>staircase effect</emphasis>, caused by
			conflicting interpretations of what characters should
			indicate a new-line. UNIX-style operating systems use
			a single character: ASCII code 10, the line feed (LF).
			MS-DOS, OS/2, and others uses a pair of characters,
			ASCII code 10 <emphasis>and</emphasis> ASCII code 13
			(the carriage return or CR). Many printers use the
			MS-DOS convention for representing new-lines.</para>
		      
		      <para>When you print with FreeBSD, your text used just
			the line feed character. The printer, upon seeing a
			line feed character, advanced the paper one line, but
			maintained the same horizontal position on the page
			for the next character to print. That is what the
			carriage return is for: to move the location of the
			next character to print to the left edge of the
			paper.</para>


		      <para>Here is what FreeBSD wants your printer to
		      do:</para>
		    
			<informaltable frame="none">
		      <tgroup cols="2">
			<tbody>
			  <row>
			    <entry>Printer received CR</entry>
			    <entry>Printer prints CR</entry>
			  </row>

			  <row>
			    <entry>Printer received LF</entry>
			    <entry>Printer prints CR + LF</entry>
			  </row>
			</tbody>
		      </tgroup>
			</informaltable>
		      
		      <para>Here are some ways to achieve this:</para>
			<itemizedlist>
			  
			  <listitem>
			    <para>Use the printer's configuration switches or
			      control panel to alter its interpretation of
			      these characters. Check your printer's manual
			      to find out how to do this.</para>

			    <note>
			      <para>If you boot your system into other
				operating systems besides FreeBSD, you may
				have to <emphasis>reconfigure</emphasis> the
				printer to use a an interpretation for CR and
				LF characters that those other operating
				systems use. You might prefer one of the
				other solutions, below.</para>
			    </note>
			  </listitem>
			  
			  <listitem>
			    <para>Have FreeBSD's serial line driver
			      automatically convert LF to CR+LF. Of course,
			      this works with printers on serial ports
			      <emphasis>only</emphasis>. To enable this
			      feature, set the CRMOD bit in <literal>fs</literal> capability in the
			      <filename>/etc/printcap</filename> file for the
			      printer.</para>
			  </listitem>
			  
			  <listitem>
			    <para>Send an <emphasis>escape code</emphasis> to
			      the printer to have it temporarily treat LF
			      characters differently. Consult your printer's
			      manual for escape codes that your printer might
			      support. When you find the proper escape code,
			      modify the text filter to send the code first,
			      then send the print job.</para>
			    
			    <para>Here is an example text filter for printers
			      that understand the Hewlett-Packard PCL escape
			      codes. This filter makes the printer treat LF
			      characters as a LF and CR; then it sends the
			      job; then it sends a form feed to eject the last
			      page of the job. It should work with nearly all
			      Hewlett Packard printers.</para>
			    
			    <programlisting>
#!/bin/sh
#
# hpif - Simple text input filter for lpd for HP-PCL based printers
# Installed in /usr/local/libexec/hpif
#
# Simply copies stdin to stdout.  Ignores all filter arguments.
# Tells printer to treat LF as CR+LF. Writes a form feed character
# after printing job.

printf "\033&amp;k2G" &amp;&amp; cat &amp;&amp; printf "\033&amp;l0H" &amp;&amp; exit 0
exit 2</programlisting>
			    
			    <para>Here is an example
			      <filename>/etc/printcap</filename> from a host
			      called orchid. It has a single printer attached
			      to its first parallel port, a Hewlett Packard
			      LaserJet 3Si named <hostid>teak</hostid>. It is using the
			      above script as its text filter:</para>

			      <programlisting>
#
#  /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
        :lp=/dev/lpt0:sh:sd=/var/spool/lpd/teak:mx#0:\
        :if=/usr/local/libexec/hpif:</programlisting>
			  </listitem>
			  
			</itemizedlist>

		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term>It overprinted each line.</term>
		    
		    <listitem>
		      <para>The printer never advanced a line. All of the
			lines of text were printed on top of each other on one
			line.</para>
		      
		      <para>This problem is the &ldquo;opposite&rdquo; of the staircase
			effect, described above, and is much rarer. Somewhere,
			the LF characters that FreeBSD uses to end a line are
			being treated as CR characters to return the print
			location to the left edge of the paper, but not also
			down a line.</para>

		      <para>Use the printer's configuration switches or
			control panel to enforce the following interpretation
			of LF and CR characters:</para>

		    <informaltable frame="none">
		      <tgroup cols="2">
			<thead>
			  <row>
			    <entry>Printer receives</entry>
			    <entry>Printer prints</entry>
			  </row>
			</thead>

			<tbody>
			  <row>
			    <entry>CR</entry>
			    <entry>CR</entry>
			  </row>

			  <row>
			    <entry>LF</entry>
			    <entry>CR + LF</entry>
			  </row>
			</tbody>
		      </tgroup>
		    </informaltable>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term>The printer lost characters.</term>
		    
		    <listitem>
		      <para>While printing, the printer did not print a few
			characters in each line. The problem might have
			gotten worse as the printer ran, losing more and more
			characters.</para>
		      
		      <para>The problem is that the printer cannot keep up
			with the speed at which the computer sends data over a
			serial line. (This problem should not occur with
			printers on parallel ports.)  There are two ways to
			overcome the problem:</para>
			<itemizedlist>
			  
			  <listitem>
			    <para>If the printer supports XON/XOFF flow
			      control, have FreeBSD use it by specifying the
			      TANDEM bit in the <literal>fs</literal> capability.</para>
			  </listitem>
			  
			  <listitem>
			    <para>If the printer supports carrier flow
			      control, specify the MDMBUF bit in the <literal>fs</literal> capability. Make sure
			      the cable connecting the printer to the computer
			      is correctly wired for carrier flow control.</para>
			  </listitem>
			  
			  <listitem>
			    <para>If the printer does not support any flow
			      control, use some combination of the NLDELAY,
			      TBDELAY, CRDELAY, VTDELAY, and BSDELAY bits in
			      the <literal>fs</literal> capability
			      to add appropriate delays to the stream of data
			      sent to the printer.</para>
			  </listitem>
			  
			</itemizedlist>

		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term>It printed garbage.</term>
		    
		    <listitem>
		      <para>The printer printed what appeared to be random
			garbage, but not the desired text.</para>
		      
		      <para>This is usually another symptom of incorrect
			communications parameters with a serial printer.
			Double-check the bps rate in the <literal>br</literal> capability, and the parity
			bits in the <literal>fs</literal> and
			<literal>fc</literal> capabilities; make
			sure the printer is using the same settings as
			specified in the <filename>/etc/printcap</filename>
			file.</para>
		    </listitem>
		  </varlistentry>
		  
		  <varlistentry><term>Nothing happened.</term>
		    
		    <listitem>
		      <para>If nothing happened, the problem is probably
			within FreeBSD and not the hardware. Add the log file
			(<literal>lf</literal>) capability to the
			entry for the printer you are debugging in the
			<filename>/etc/printcap</filename> file. For example,
			here is the entry for <literal>rattan</literal>, with
		      the <literal>lf</literal> capability:</para>

			<programlisting>
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:\
        :lf=/var/log/rattan.log</programlisting>
			<para>Then, try printing again. Check
			the log file (in our example,
			<filename>/var/log/rattan.log</filename>) to see any
			error messages that might appear. Based on the
			messages you see, try to correct the problem.</para>
		      
		      <para>If you do not specify a <literal>lf</literal> capability, LPD uses
			<filename>/dev/console</filename> as a default.</para>
		      
		    </listitem>
		  </varlistentry>
		</variablelist>
	      
	    </sect4>
	  </sect3>
	</sect2>
      </sect1>
      
      <sect1 id="printing-using">
	<title>Using Printers</title>
	
	<para>This section tells you how to use printers you have setup with
	  FreeBSD. Here is an overview of the user-level commands:</para>
	
	  <variablelist>
	    <varlistentry><term><citerefentry>
		  <refentrytitle>lpr</refentrytitle></citerefentry></term>
	      <listitem>
		<para>Print jobs</para>
	      </listitem>
	    </varlistentry>
	    
	    <varlistentry><term><citerefentry>
		  <refentrytitle>lpq</refentrytitle></citerefentry></term>
	      
	      <listitem>
		<para>Check printer queues</para>
	      </listitem>
	    </varlistentry>
	    
	    <varlistentry><term><citerefentry>
		  <refentrytitle>lprm</refentrytitle></citerefentry></term>
	      
	      <listitem>
		<para>Remove jobs from a printer's queue</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>
		
	<para>There is also an administrative command, <citerefentry>
	    <refentrytitle>lpc</refentrytitle></citerefentry>,
	  described in the section <link linkend="printing-lpc">Administrating the
	    LPD Spooler</link>, used to control printers and their queues.</para>
	
	<para>All three of the commands  <citerefentry>
	    <refentrytitle>lpr</refentrytitle></citerefentry>, <citerefentry>
	    <refentrytitle>lprm</refentrytitle></citerefentry>, and
	  <citerefentry>
	    <refentrytitle>lpq</refentrytitle></citerefentry>
	  accept an option <option>-P <replaceable>printer-name</replaceable></option> to specify on which
	  printer/queue to operate, as listed in the
	  <filename>/etc/printcap</filename> file. This enables you to
	  submit, remove, and check on jobs for various printers. If you do
	  not use the <option>-P</option> option, then these commands use the
	  printer specified in the <envar>PRINTER</envar> environment variable. Finally, if
	  you do not have a <envar>PRINTER</envar> environment variable, these commands
	  default to the printer named <literal>lp</literal>.</para>
	
	<para>Hereafter, the terminology <emphasis>default printer</emphasis>
	  means the printer named in the <envar>PRINTER</envar> environment variable, or the
	  printer named <literal>lp</literal> when there is no
	  <envar>PRINTER</envar> environment variable.</para>
	
	
	<sect2 id="printing-lpr">
	  <title>Printing Jobs</title>
	  
	  <para>To print files, type:</para>
	    
	    <informalexample>
	      <screen>&prompt.user; <userinput>lpr <replaceable>filename</replaceable> <replaceable>...</replaceable></userinput></screen>
	    </informalexample>

	  <para>This prints each of the listed files to the
	    default printer. If you list no files, <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry> reads
	    data to print from standard input. For example, this command
	    prints some important system files:</para>
	    
	    <informalexample>
	      <screen>&prompt.user; <userinput>lpr /etc/host.conf /etc/hosts.equiv</userinput></screen>
	    </informalexample>

	  <para>To select a specific printer, type:</para>
	    
	    <informalexample>
	      <screen>&prompt.user; <userinput>lpr -P <replaceable>printer-name</replaceable> <replaceable>filename</replaceable> <replaceable>...</replaceable></userinput></screen>
	    </informalexample>

	  <para>This example prints a long listing of the
	    current directory to the printer named <literal>rattan</literal>:</para>
	    
	    <informalexample>
	      <screen>&prompt.user; <userinput>ls -l | lpr -P rattan</userinput></screen>
	    </informalexample>

	  <para>Because no files were listed for the
	    <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry>
	    command, <command>lpr</command> read the data to print
	    from standard input, which was the output of the <command>ls
	      -l</command> command.</para>
	  
	  <para>The <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry> command
	    can also accept a wide variety of options to control formatting,
	    apply file conversions, generate multiple copies, and so forth.
	    For more information, see the section <link
	      linkend="printing-lpr-options">Printing Options</link>.</para>
	  
	</sect2>
	
	<sect2 id="printing-lpq">
	  <title>Checking Jobs</title>
	  
	  <para>When you print with  <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry>, the
	    data you wish to print is put together in a package called a
	    &ldquo;print job&rdquo;, which is sent to the LPD spooling
	    system. Each printer has a queue of jobs, and your job waits in
	    that queue along with other jobs from yourself and from other
	    users. The printer prints those jobs in a first-come, first-served
	    order.</para>
	  
	  <para>To display the queue for the default printer, type
	    <citerefentry>
	      <refentrytitle>lpq</refentrytitle></citerefentry>. For a
	    specific printer, use the <option>-P</option> option. For
	    example, the command
	    
	    <informalexample>
	      <screen>&prompt.user; <userinput>lpq -P bamboo</userinput></screen>
	    </informalexample> shows the queue for the printer named <hostid>bamboo</hostid>. Here is an example of the output of
	    the <command>lpq</command> command:</para>
	    
	    <informalexample>
	      <screen>bamboo is ready and printing
Rank   Owner    Job  Files                              Total Size
active kelly    9    /etc/host.conf, /etc/hosts.equiv   88 bytes
2nd    kelly    10   (standard input)                   1635 bytes
3rd    mary     11   ...                                78519 bytes</screen>
	    </informalexample>

	  <para>This shows three jobs in the queue for
	    <literal>bamboo</literal>. The first job, submitted by
	    user kelly, got assigned &ldquo;job number&rdquo; 9. Every
	    job for a printer gets a unique job number. Most of the time you
	    can ignore the job number, but you will need it if you want to
	    cancel the job; see section
	    <link linkend="printing-lprm">Removing Jobs</link> for
	    details.</para>
	  
	  <para>Job number nine consists of two files; multiple files given on
	    the  <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry> command
	    line are treated as part of a single job. It is the currently
	    active job (note the word <literal>active</literal>
	    under the &ldquo;Rank&rdquo; column), which means the printer should be
	    currently printing that job. The second job consists of data
	    passed as the standard input to the</para>
	  
	  <para><citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry>
	    command. The third job came from user mary; it is a much larger
	    job. The pathname of the files she's trying to print is too long
	    to fit, so the  <citerefentry>
	      <refentrytitle>lpq</refentrytitle></citerefentry> command
	    just shows three dots.</para>
	  
	  <para>The very first line of the output from  <citerefentry>
	      <refentrytitle>lpq</refentrytitle></citerefentry> is also
	    useful: it tells what the printer is currently doing (or at least
	    what LPD thinks the printer is doing).</para>
	  
	  <para>The  <citerefentry>
	      <refentrytitle>lpq</refentrytitle></citerefentry> command
	    also support a <option>-l</option> option to generate a detailed
	    long listing. Here is an example of <command>lpq -l</command>:</para>
	    
	    <informalexample>
	      <screen>waiting for bamboo to become ready (offline ?)
kelly: 1st				 [job 009rose]
       /etc/host.conf                    73 bytes
       /etc/hosts.equiv                  15 bytes

kelly: 2nd				 [job 010rose]
       (standard input)		         1635 bytes

mary: 3rd                                [job 011rose]
      /home/orchid/mary/research/venus/alpha-regio/mapping 78519 bytes</screen>
	    </informalexample>
	  
	</sect2>
	
	<sect2 id="printing-lprm">
	  <title>Removing Jobs</title>
	  
	  <para>If you change your mind about printing a job, you can remove
	    the job from the queue with the  <citerefentry>
	      <refentrytitle>lprm</refentrytitle></citerefentry>
	    command. Often, you can even use  <citerefentry>
	      <refentrytitle>lprm</refentrytitle></citerefentry> to
	    remove an active job, but some or all of the job might still get
	    printed.</para>
	  
	  <para>To remove a job from the default printer, first use
	    <citerefentry>
	      <refentrytitle>lpq</refentrytitle></citerefentry> to find
	    the job number. Then type:</para>
	  
	    <informalexample>
	      <screen>&prompt.user; <userinput>lprm <replaceable>job-number</replaceable></userinput></screen>
	    </informalexample>

	  <para>To remove the job from a specific printer, add
	    the <option>-P</option> option. The following command removes job
	    number 10 from the queue for the printer
	    <hostid>bamboo</hostid>:</para>
	  
	    <informalexample>
	      <screen>&prompt.user; <userinput>lprm -P bamboo 10</userinput></screen>
	    </informalexample>

	  <para>The  <citerefentry>
	      <refentrytitle>lprm</refentrytitle></citerefentry>
	    command has a few shortcuts:</para>
	  
	    <variablelist>
	      <varlistentry><term>lprm -</term>
		<listitem>
		  <para>Removes all jobs (for the default printer) belonging
		    to you.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term>lprm <replaceable>user</replaceable></term>
		
		<listitem>
		  <para>Removes all jobs (for the default printer) belonging
		    to <replaceable>user</replaceable>. The superuser can
		    remove other users' jobs; you can remove only your own
		    jobs.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term>lprm</term>
		
		<listitem>
		  <para>With no job number, user name, or
		    <option>-</option> appearing on the command line,
		    <citerefentry>
		      <refentrytitle>lprm</refentrytitle></citerefentry> removes the currently active job on the default printer, if it belongs to you. The superuser can remove any active job.</para>
		  
		</listitem>
	      </varlistentry>
	    </variablelist>
	  
	  <para>Just use the <option>-P</option> option with the above
	    shortcuts to operate on a specific printer instead of the default.
	    For example, the following command removes all jobs for the
	    current user in the queue for the printer named <literal>rattan</literal>:</para>
	  
	  <informalexample>
	    <screen>&prompt.user; <userinput>lprm -P rattan -</userinput></screen>
	  </informalexample>

	  <note>
	    <para>If you are working in a networked
	      environment, <citerefentry>
		<refentrytitle>lprm</refentrytitle></citerefentry>
	      will let you remove jobs only from the host from which the jobs
	      were submitted, even if the same printer is available from other
	      hosts. The following command sequence demonstrates this:</para>
	      
	      <informalexample>
		<screen>&prompt.user; <userinput>lpr -P rattan myfile</userinput>
&prompt.user; <userinput>rlogin orchid</userinput>
&prompt.user; <userinput>lpq -P rattan</userinput>
Rank   Owner	  Job  Files                          Total Size
active seeyan	  12	...                           49123 bytes
2nd    kelly      13   myfile                         12 bytes
&prompt.user; <userinput>lprm -P rattan 13</userinput>
rose: Permission denied
&prompt.user; <userinput>logout</userinput>
&prompt.user; <userinput>lprm -P rattan 13</userinput>
dfA013rose dequeued
cfA013rose dequeued
		</screen>
	      </informalexample>
	  </note>
	</sect2>
	
	<sect2 id="printing-lpr-options">
	  <title>Beyond Plain Text: Printing Options</title>
	  
	  <para>The  <citerefentry>
	      <refentrytitle>lpr</refentrytitle></citerefentry> command
	    supports a number of options that control formatting text,
	    converting graphic and other file formats, producing multiple
	    copies, handling of the job, and more. This section describes the
	    options.</para>
	  
	  
	  <sect3 id="printing-lpr-options-format">
	    <title>Formatting and Conversion Options</title>
	    
	    <para>The following  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>
	      options control formatting of the files in the job. Use these
	      options if the job does not contain plain text or if you want
	      plain text formatted through the  <citerefentry>
		<refentrytitle>pr</refentrytitle></citerefentry>
	      utility.</para>
	    
	    <para>For example, the following command prints a DVI file (from
	      the TeX typesetting system) named
	      <filename>fish-report.dvi</filename> to the printer named
	      <literal>bamboo</literal>:</para>
	      <informalexample>
		<screen>&prompt.user; <userinput>lpr -P bamboo -d fish-report.dvi</userinput></screen>
	      </informalexample>

	    <para>These options apply to every file in the job,
	      so you cannot mix (say) DVI and ditroff files together in a job.
	      Instead, submit the files as separate jobs, using a different
	      conversion option for each job.</para>

	    <note>
	      <para>All of these options except <option>-p</option> and
		<option>-T</option> require conversion filters installed for
		the destination printer. For example, the <option>-d</option>
		option requires the DVI conversion filter. Section <link
		linkend="printing-advanced-convfilters">Conversion
		Filters</link> gives details.</para>
	    </note>
	    
	    
	      <variablelist>
		<varlistentry><term><option>-c</option></term>
		  <listitem>
		    <para>Print cifplot files.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-d</option></term>
		  
		  <listitem>
		    <para>Print DVI files.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-f</option></term>
		  
		  <listitem>
		    <para>Print FORTRAN text files.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-g</option></term>
		  
		  <listitem>
		    <para>Print plot data.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-i
		      <replaceable>number</replaceable></option></term>
		  
		  <listitem>
		    <para>Indent the output by <replaceable>number</replaceable> columns; if you omit
		      <replaceable>number</replaceable>, indent by 8
		      columns. This option works only with certain conversion
		      filters.</para>

		    <note>
		      <para>Do not put any space between the
			<option>-i</option> and the number.</para>
		    </note>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-l</option></term>
		  
		  <listitem>
		    <para>Print literal text data, including control
		      characters.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-n</option></term>
		  
		  <listitem>
		    <para>Print ditroff (device independent troff)
		      data.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-p</term>
		  
		  <listitem>
		    <para>Format plain text with  <citerefentry>
			<refentrytitle>pr</refentrytitle></citerefentry>
		      before printing. See <citerefentry><refentrytitle>pr</refentrytitle><manvolnum>1</manvolnum></citerefentry> for more information.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-T
		      <replaceable>title</replaceable></option></term>
		  
		  <listitem>
		    <para>Use <replaceable>title</replaceable> on the
		      <citerefentry>
			<refentrytitle>pr</refentrytitle></citerefentry>
		      header instead of the file name. This option has effect
		      only when used with the <option>-p</option>
		      option.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-t</option></term>
		  
		  <listitem>
		    <para>Print troff data.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-v</option></term>
		  
		  <listitem>
		    <para>Print raster data.</para>
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    
	    <para>Here is an example: this command prints a nicely formatted
	      version of the  <citerefentry>
		<refentrytitle>ls</refentrytitle></citerefentry> manual
	      page on the default printer:</para>
	    
	      <informalexample>
		<screen>&prompt.user; <userinput>zcat /usr/share/man/man1/ls.1.gz | troff -t -man | lpr -t</userinput></screen>
	      </informalexample>

	    <para>The  <citerefentry>
		<refentrytitle>zcat</refentrytitle></citerefentry>
	      command uncompresses the source of the</para>
	    
	    <para><citerefentry>
		<refentrytitle>ls</refentrytitle></citerefentry> manual
	      page and passes it to the  <citerefentry>
		<refentrytitle>troff</refentrytitle></citerefentry>
	      command, which formats that source and makes GNU troff output
	      and passes it to  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>,
	      which submits the job to the LPD spooler. Because we used the
	      <option>-t</option> option to</para>
	    
	    <para><citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>, the
	      spooler will convert the GNU troff output into a format the
	      default printer can understand when it prints the job.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-lpr-options-job-handling">
	    <title>Job Handling Options</title>
	    
	    <para>The following options to  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry> tell
	      LPD to handle the job specially:</para>
	    
	    
	      <variablelist>
		<varlistentry><term>-# <replaceable>copies</replaceable></term>
		  <listitem>
		    <para>Produce a number of <replaceable>copies</replaceable> of each file in the job
		      instead of just one copy. An administrator may disable
		      this option to reduce printer wear-and-tear and
		      encourage photocopier usage. See section <link
			linkend="printing-advanced-restricting-copies">Restricting Multiple Copies</link>.</para>

		    <para>This example prints three copies of
		      <filename>parser.c</filename> followed by three copies
		      of <filename>parser.h</filename> to the default
		      printer:</para>
		    
		      <informalexample>
			<screen>&prompt.user; <userinput>lpr -#3 parser.c parser.h</userinput></screen>
		      </informalexample>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-m</term>
		  
		  <listitem>
		    <para>Send mail after completing the print job. With this
		      option, the LPD system will send mail to your account
		      when it finishes handling your job. In its message, it
		      will tell you if the job completed successfully or if
		      there was an error, and (often) what the error
		      was.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-s</term>
		  
		  <listitem>
		    <para>Do not copy the files to the spooling directory, but
		      make symbolic links to them instead.</para>
		    
		    <para>If you are printing a large job, you probably want
		      to use this option. It saves space in the spooling
		      directory (your job might overflow the free space on the
		      filesystem where the spooling directory resides). It
		      saves time as well since LPD will not have to copy each
		      and every byte of your job to the spooling
		      directory.</para>
		    
		    <para>There is a drawback, though: since LPD will refer to
		      the original files directly, you cannot modify or remove
		      them until they have been printed.</para>

		    <note>
		      <para>If you are printing to a remote printer, LPD will
			eventually have to copy files from the local host to
			the remote host, so the <option>-s</option> option
			will save space only on the local spooling directory,
			not the remote. It is still useful, though.</para>
		    </note>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-r</term>
		  
		  <listitem>
		    <para>Remove the files in the job after copying them to
		      the spooling directory, or after printing them with the
		      <option>-s</option> option. Be careful with this
		      option!</para>
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    
	  </sect3>
	  
	  <sect3 id="printing-lpr-options-misc">
	    <title>Header Page Options</title>
	    
	    <para>These options to  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>
	      adjust the text that normally appears on a job's header page.
	      If header pages are suppressed for the destination printer,
	      these options have no effect. See section <link
		linkend="printing-advanced-header-pages">Header Pages</link>
	      for information about setting up header pages.</para>
	    
	    
	      <variablelist>
		<varlistentry><term>-C <replaceable>text</replaceable></term>
		  <listitem>
		    <para>Replace the hostname on the header page with
		      <replaceable>text</replaceable>. The hostname is
		      normally the name of the host from which the job was
		      submitted.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-J <replaceable>text</replaceable></term>
		  
		  <listitem>
		    <para>Replace the job name on the header page with
		      <replaceable>text</replaceable>. The job name is
		      normally the name of the first file of the job, or
		      <filename>stdin</filename> if you are printing standard input.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>-h</term>
		  
		  <listitem>
		    <para>Do not print any header page.</para>

		    <note>
		      <para>At some sites, this option may have no effect due
			to the way header pages are generated. See <link
			linkend="printing-advanced-header-pages">Header
			Pages</link> for details.</para>
		    </note>
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-lpc">
	  <title>Administrating Printers</title>
	  
	  <para>As an administrator for your printers, you have had to
	    install, set up, and test them. Using the  <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry>
	    command, you can interact with your printers in yet more ways.
	    With <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry>, you
	    can</para>
	  
	  
	    <itemizedlist>
	      
	      <listitem>
		<para>Start and stop the printers</para>
	      </listitem>
	      
	      <listitem>
		<para>Enable and disable their queues</para>
	      </listitem>
	      
	      <listitem>
		<para>Rearrange the order of the jobs in each queue.</para>
	      </listitem>
	      
	    </itemizedlist>
	  
	  
	  <para>First, a note about terminology: if a printer is
	    <emphasis>stopped</emphasis>, it will not print anything in its
	    queue. Users can still submit jobs, which will wait in the queue
	    until the printer is <emphasis>started</emphasis> or the queue is
	    cleared.</para>
	  
	  <para>If a queue is <emphasis>disabled</emphasis>, no user (except
	    root) can submit jobs for the printer. An
	    <emphasis>enabled</emphasis> queue allows jobs to be submitted. A
	    printer can be <emphasis>started</emphasis> for a disabled queue,
	    in which case it will continue to print jobs in the queue until
	    the queue is empty.</para>
	  
	  <para>In general, you have to have root privileges to use the <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry>
	    command. Ordinary users can use the  <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry> command
	    to get printer status and to restart a hung printer only.</para>
	  
	  <para>Here is a summary of the  <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry>
	    commands. Most of the commands takes a <replaceable>printer-name</replaceable> argument to tell on which
	    printer to operate. You can use <literal>all</literal>
	    for the <replaceable>printer-name</replaceable> to mean all
	    printers listed in <filename>/etc/printcap</filename>.</para>
	  
	  
	    <variablelist>
	      <varlistentry><term><command>abort
		    <replaceable>printer-name</replaceable></command></term>
		<listitem>
		  <para>Cancel the current job and stop the printer. Users
		    can still submit jobs if the queue's enabled.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>clean
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Remove old files from the printer's spooling
		    directory. Occasionally, the files that make up a job are
		    not properly removed by LPD, particularly if there have
		    been errors during printing or a lot of administrative
		    activity. This command finds files that do not belong in
		    the spooling directory and removes them.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>disable
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Disable queuing of new jobs. If the printer's
		    started, it will continue to print any jobs remaining in
		    the queue. The superuser (root) can always submit jobs,
		    even to a disabled queue.</para>
		  
		  <para>This command is useful while you are testing a new
		    printer or filter installation: disable the queue and
		    submit jobs as root. Other users will not be able to
		    submit jobs until you complete your testing and re-enable
		    the queue with the <command>enable</command>
		    command.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>down
		    <replaceable>printer-name</replaceable>
		    <replaceable>message</replaceable></command></term>
		
		<listitem>
		  <para>Take a printer down. Equivalent to
		  <command>disable</command> followed by
		  <command>stop</command>. The <replaceable>message</replaceable> appears as the printer's
		    status whenever a user checks the printer's queue with
		    <citerefentry>
		      <refentrytitle>lpq</refentrytitle></citerefentry>
		    or status with <command>lpc
		      status</command>.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>enable
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Enable the queue for a printer. Users can submit jobs
		    but the printer will not print anything until it is
		    started.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>help
		    <replaceable>command-name</replaceable></command></term>
		
		<listitem>
		  <para>Print help on the command
		  <replaceable>command-name</replaceable>. With no
		  <replaceable>command-name</replaceable>, print a summary of the
		    commands available.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>restart
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Start the printer. Ordinary users can use this
		    command if some extraordinary circumstance hangs LPD, but
		    they cannot start a printer stopped with either the
		    <command>stop</command> or <command>down</command> commands. The <command>restart</command> command is equivalent to
		    <command>abort</command> followed by <command>start</command>.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>start
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Start the printer. The printer will print jobs in its
		    queue.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>stop
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Stop the printer. The printer will finish the current
		    job and will not print anything else in its queue. Even
		    though the printer is stopped, users can still submit jobs
		    to an enabled queue.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>topq
		    <replaceable>printer-name</replaceable>
		    <replaceable>job-or-username</replaceable></command></term>
		
		<listitem>
		  <para>Rearrange the queue for <replaceable>printer-name</replaceable> by placing the jobs
		    with the listed <replaceable>job</replaceable> numbers
		    or the jobs belonging to <replaceable>username</replaceable> at the top of the queue.
		    For this command, you cannot use <literal>all</literal> as
		  the <replaceable>printer-name</replaceable>.</para>
		</listitem>
	      </varlistentry>
	      
	      <varlistentry><term><command>up
		    <replaceable>printer-name</replaceable></command></term>
		
		<listitem>
		  <para>Bring a printer up; the opposite of the <command>down</command> command. Equivalent to
		    <command>start</command> followed by <command>enable</command>.</para>
		</listitem>
	      </varlistentry>
	    </variablelist>
	  
	  
	  <para><citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry> accepts
	    the above commands on the command line. If you do not enter any
	    commands, <citerefentry>
	      <refentrytitle>lpc</refentrytitle></citerefentry> enters
	    an interactive mode, where you can enter commands until you type
	    <command>exit</command>, <command>quit</command>, or end-of-file.</para>
	  
	</sect2>
      </sect1>
      
      <sect1 id="printing-advanced">
	<title>Advanced Printer Setup</title>
	
	<para>This section describes filters for printing specially formatted
	  files, header pages, printing across networks, and restricting and
	  accounting for printer usage.</para>
	
	
	<sect2 id="printing-advanced-filter-intro">
	  <title>Filters</title>
	  
	  <para>Although LPD handles network protocols, queuing, access
	    control, and other aspects of printing, most of the
	    <emphasis>real</emphasis> work happens in the
	    <emphasis>filters</emphasis>. Filters are programs that
	    communicate with the printer and handle its device dependencies
	    and special requirements. In the simple printer setup, we
	    installed a plain text filter&mdash;an extremely simple one that
	    should work with most printers (section <link
	      linkend="printing-textfilter">Installing the
	      Text Filter</link>).</para>
	  
	  <para>However, in order to take advantage of format conversion,
	    printer accounting, specific printer quirks, and so on, you should
	    understand how filters work. It will ultimately be the filter's
	    responsibility to handle these aspects. And the bad news is that
	    most of the time <emphasis>you</emphasis> have to provide filters
	    yourself. The good news is that many are generally available;
	    when they are not, they are usually easy to write.</para>
	  
	  <para>Also, FreeBSD comes with one,
	    <filename>/usr/libexec/lpr/lpf</filename>, that works with many
	    printers that can print plain text. (It handles backspacing and
	    tabs in the file, and does accounting, but that is about all it
	    does.)  There are also several filters and filter components in
	    the FreeBSD ports collection.</para>
	  
	  <para>Here is what you will find in this section:</para>
	  
	  
	    <itemizedlist>
	      
	      <listitem>
		<para>Section <link linkend="printing-advanced-filters">How Filters Work</link>, tries to give an overview of a
		  filter's role in the printing process. You should read this
		  section to get an understanding of what is happening &ldquo;under
		  the hood&rdquo; when LPD uses filters. This knowledge could help
		  you anticipate and debug problems you might encounter as you
		  install more and more filters on each of your printers.</para>
	      </listitem>
	      
	      <listitem>
		<para>LPD expects every printer to be able to print plain text
		  by default. This presents a problem for PostScript (or
		  other language-based printers) which cannot directly print
		  plain text. Section <link
		    linkend="printing-advanced-if-conversion">Accommodating        Plain Text Jobs on PostScript
		    Printers</link> tells you what you should do to overcome this
		  problem. I recommend reading this section if you have a
		  PostScript printer.</para>
	      </listitem>
	      
	      <listitem>
		<para>PostScript is a popular output format for many programs.
		  Even some people (myself included) write PostScript code
		  directly. But PostScript printers are expensive. Section
		  <link linkend="printing-advanced-ps">Simulating PostScript on Non-PostScript Printers</link>
		  tells how you can further modify a printer's text filter to
		  accept and print PostScript data on a
		  <emphasis>non-PostScript</emphasis> printer. I recommend
		  reading this section if you do not have a PostScript
		  printer.</para>
	      </listitem>
	      
	      <listitem>
		<para>Section <link linkend="printing-advanced-convfilters">Conversion Filters</link> tells about a way you can
		  automate the conversion of specific file formats, such as
		  graphic or typesetting data, into formats your printer can
		  understand. After reading this section, you should be able
		  to set up your printers such that users can type
		  <command>lpr -t</command> to print troff data, or
		  <command>lpr -d</command> to print TeX DVI data, or
		  <command>lpr -v</command> to print raster image data, and so
		  forth. I recommend reading this section.</para>
	      </listitem>
	      
	      <listitem>
		<para>Section <link linkend="printing-advanced-of">Output   Filters</link> tells all about a not often used
		  feature of LPD: output filters. Unless you are printing
		  header pages (see <link
		    linkend="printing-advanced-header-pages">Header Pages</link>), you can probably skip that section
		  altogether.</para>
	      </listitem>
	      
	      <listitem>
		<para>Section <link linkend="printing-advanced-lpf">lpf: a Text Filter</link> describes <command>lpf</command>, a fairly complete if simple text
		  filter for line printers (and laser printers that act like
		  line printers) that comes with FreeBSD. If you need a quick
		  way to get printer accounting working for plain text, or if
		  you have a printer which emits smoke when it sees backspace
		  characters, you should definitely consider <command>lpf</command>.</para>
	      </listitem>
	      
	    </itemizedlist>
	  
	  
	  <sect3 id="printing-advanced-filters">
	    <title>How Filters Work</title>
	    
	    <para>As mentioned before, a filter is an executable program
	      started by LPD to handle the device-dependent part of
	      communicating with the printer.</para>
	    
	    <para>When LPD wants to print a file in a job, it starts a filter
	      program. It sets the filter's standard input to the file to
	      print, its standard output to the printer, and its standard
	      error to the error logging file (specified in the <literal>lf</literal> capability in
	      <filename>/etc/printcap</filename>, or
	      <filename>/dev/console</filename> by default).</para>
	    
	    <para>Which filter LPD starts and the filter's arguments depend on
	      what is listed in the <filename>/etc/printcap</filename> file
	      and what arguments the user specified for the job on the</para>
	    
	    <para><citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>
	      command line. For example, if the user typed <command>lpr
		-t</command>, LPD would start the troff filter, listed in the
	      <literal>tf</literal> capability for the destination
	      printer. If the user wanted to print plain text, it would start
	      the <literal>if</literal> filter (this is mostly
	      true:
	      see <link linkend="printing-advanced-of">Output Filters</link>
	      for details).</para>
	    
	    <para>There are three kinds of filters you can specify in
	      <filename>/etc/printcap</filename>:</para>
	    
	      <itemizedlist>
		
		<listitem>
		  <para>The <emphasis>text filter</emphasis>, confusingly
		    called the <emphasis>input filter</emphasis> in LPD
		    documentation, handles regular text printing. Think of it
		    as the default filter. LPD expects every printer to be
		    able to print plain text by default, and it is the text
		    filter's job to make sure backspaces, tabs, or other
		    special characters do not confuse the printer. If you are
		    in an environment where you have to account for printer
		    usage, the text filter must also account for pages
		    printed, usually by counting the number of lines printed
		    and comparing that to the number of lines per page the
		    printer supports. The text filter is started with the
		    following argument list:
		  
		    <cmdsynopsis>
		      <command>filter-name</command>
		      <arg>-c</arg>
		      <arg choice="plain">-w<replaceable>width</replaceable></arg>
		      <arg choice="plain">-l<replaceable>length</replaceable></arg>
		      <arg choice="plain">-i<replaceable>indent</replaceable></arg>
		      <arg choice="plain">-n <replaceable>login</replaceable></arg>
		      <arg choice="plain">-h <replaceable>host</replaceable></arg>
		      <arg choice="plain"><replaceable>acct-file</replaceable></arg>
		    </cmdsynopsis> where
		  
		    <variablelist>
		      <varlistentry><term><option>-c</option></term>
			<listitem>
			  <para>appears if the job's submitted with
			    <command>lpr -l</command></para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>width</replaceable></term>
			
			<listitem>
			  <para>is the value from the <literal>pw</literal> (page width) capability
			    specified in <filename>/etc/printcap</filename>,
			    default 132</para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>length</replaceable></term>
			
			<listitem>
			  <para>is the value from the <literal>pl</literal> (page length) capability,
			    default 66</para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>indent</replaceable></term>
			
			<listitem>
			  <para>is the amount of the indentation from
			    <command>lpr -i</command>, default 0</para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>login</replaceable></term>
			
			<listitem>
			  <para>is the account name of the user printing the
			    file</para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>host</replaceable></term>
			
			<listitem>
			  <para>is the host name from which the job was
			    submitted</para>
			</listitem>
		      </varlistentry>
		      
		      <varlistentry><term><replaceable>acct-file</replaceable></term>
			
			<listitem>
			  <para>is the name of the accounting file from the
			    <literal>af</literal>
			    capability.</para>
			</listitem>
		      </varlistentry>
		    </variablelist>
		    
		  </para>
		</listitem>
		
		<listitem>
		  <para>A <emphasis>conversion filter</emphasis> converts a
		    specific file format into one the printer can render onto
		    paper. For example, ditroff typesetting data cannot be
		    directly printed, but you can install a conversion filter
		    for ditroff files to convert the ditroff data into a form
		    the printer can digest and print. Section
		    <link linkend="printing-advanced-convfilters">Conversion Filters</link> tells all about them.
		    Conversion filters also need to do accounting, if you need
		    printer accounting. Conversion filters are started with
		    the following arguments:
		  
		    <cmdsynopsis>
		      <command>filter-name</command>
		      <arg
			choice="plain">-x<replaceable>pixel-width</replaceable></arg>
		      <arg choice="plain">-y<replaceable>pixel-height</replaceable></arg>
		      <arg choice="plain">-n <replaceable>login</replaceable></arg>
		      <arg choice="plain">-h <replaceable>host</replaceable></arg>
		      <arg choice="plain"><replaceable>acct-file</replaceable></arg>
		    </cmdsynopsis> where <replaceable>pixel-width</replaceable> is the value from the
		    <literal>px</literal> capability (default 0)
		    and <replaceable>pixel-height</replaceable> is the
		    value from the <literal>py</literal> capability
		    (default 0).</para>
		</listitem>
		
		<listitem>
		  <para>The <emphasis>output filter</emphasis> is used only if
		    there is no text filter, or if header pages are enabled.
		    In my experience, output filters are rarely used. Section
		    <link linkend="printing-advanced-of">Output
		      Filters</link> describe them. There are only two arguments
		    to an output filter:
		  
		    <cmdsynopsis>
		      <command>filter-name</command>
		      <arg choice="plain">-w<replaceable>width</replaceable></arg>

		      <arg choice="plain">-l<replaceable>length</replaceable></arg>
		    </cmdsynopsis> which are identical to the text filters
		    <option>-w</option> and <option>-l</option>
		    arguments.</para>
		</listitem>
		
	      </itemizedlist>
	    
	    <para>Filters should also <emphasis>exit</emphasis> with the
	      following exit status:</para>
	    
	      <variablelist>
		<varlistentry><term>exit 0</term>
		  <listitem>
		    <para>If the filter printed the file successfully.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>exit 1</term>
		  
		  <listitem>
		    <para>If the filter failed to print the file but wants LPD
		      to try to print the file again. LPD will restart a
		      filter if it exits with this status.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>exit 2</term>
		  
		  <listitem>
		    <para>If the filter failed to print the file and does not
		      want LPD to try again. LPD will throw out the
		      file.</para>
		    
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    <para>The text filter that comes with the FreeBSD release,
	      <filename>/usr/libexec/lpr/lpf</filename>, takes advantage of
	      the page width and length arguments to determine when to send a
	      form feed and how to account for printer usage. It uses the
	      login, host, and accounting file arguments to make the
	      accounting entries.</para>
	    
	    <para>If you are shopping for filters, see if they are
	      LPD-compatible. If they are, they must support the argument
	      lists described above. If you plan on writing filters for
	      general use, then have them support the same argument lists and
	      exit codes.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-if-conversion">
	    <title>Accommodating Plain Text Jobs on PostScript Printers</title>
	    
	    <para>If you are the only user of your computer and PostScript
	      (or other language-based) printer, and you promise to never send
	      plain text to your printer and to never use features of various
	      programs that will want to send plain text to your printer, then
	      you do not need to worry about this section at all.</para>
	    
	    <para>But, if you would like to send both PostScript and plain
	      text jobs to the printer, then you are urged to augment your
	      printer setup. To do so, we have the text filter detect if the
	      arriving job is plain text or PostScript. All PostScript jobs
	      must start with <literal>%!</literal> (for other
	      printer languages, see your printer documentation). If those are
	      the first two characters in the job, we have PostScript, and can
	      pass the rest of the job directly. If those are not the first
	      two characters in the file, then the filter will convert the
	      text into PostScript and print the result.</para>
	    
	    <para>How do we do this?</para>
	    
	    <para>If you have got a serial printer, a great way to do it is to
	      install <command>lprps</command>. <command>lprps</command> is a PostScript printer filter which
	      performs two-way communication with the printer. It updates the
	      printer's status file with verbose information from the printer,
	      so users and administrators can see exactly what the state of
	      the printer is (such as <errorname>toner low</errorname> or <errorname>paper jam</errorname>). But
	      more importantly, it includes a program called <command>psif</command> which detects whether the incoming
	      job is plain text and calls <command>textps</command>
	      (another program that comes with <command>lprps</command>) to convert it to PostScript. It
	      then uses <command>lprps</command> to send the job to
	      the printer.</para>
	    
	    <para><command>lprps</command> is part of the FreeBSD
	      ports collection (see <link linkend="ports">The Ports
		Collection</link>). You
	      can fetch, build and install it yourself, of course. After
	      installing <command>lprps</command>, just specify the
	      pathname to the <command>psif</command> program that
	      is part of <command>lprps</command>. If you
	      installed <command>lprps</command> from the ports
	      collection, use the following in the serial PostScript printer's
	      entry in <filename>/etc/printcap</filename>:</para>
	      
	      <programlisting>
:if=/usr/local/libexec/psif:</programlisting>

	    <para>You should also specify the <literal>rw</literal> capability; that tells LPD to open the
	      printer in read-write mode.</para>
	    
	    <para>If you have a parallel PostScript printer (and therefore
	      cannot use two-way communication with the printer, which
	      <command>lprps</command> needs), you can use the
	      following shell script as the text filter:</para>

		<programlisting>
#!/bin/sh
#
#  psif - Print PostScript or plain text on a PostScript printer
#  Script version; NOT the version that comes with lprps
#  Installed in /usr/local/libexec/psif
#

read first_line
first_two_chars=`expr "$first_line" : '\(..\)'`

if [ "$first_two_chars" = "%!" ]; then
    #
    #  PostScript job, print it.
    #
    echo "$first_line" &amp;&amp; cat &amp;&amp; printf "\004" &amp;&amp; exit 0
    exit 2
else
    #
    #  Plain text, convert it, then print it.
    #
    ( echo "$first_line"; cat ) | /usr/local/bin/textps &amp;&amp; printf "\004" &amp;&amp; exit 0
    exit 2
fi</programlisting>
	    
	    <para>In the above script, <command>textps</command> is a program we installed
	      separately to convert plain text to PostScript. You can use any
	      text-to-PostScript program you wish. The FreeBSD ports
	      collection (see <link linkend="ports">The Ports
		Collection</link>) includes a full featured text-to-PostScript
	      program called  <citerefentry>
		<refentrytitle>a2ps</refentrytitle></citerefentry> that you might want to investigate.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-ps">
	    <title>Simulating PostScript on Non-PostScript Printers</title>
	    
	    <para>PostScript is the <emphasis>de facto</emphasis>
	      standard for high quality typesetting and printing. PostScript
	      is, however, an <emphasis>expensive</emphasis> standard.
	      Thankfully, Alladin Enterprises has a free PostScript work-alike
	      called <application>Ghostscript</application> that runs with
	      FreeBSD. Ghostscript can read most PostScript files and can
	      render their pages onto a variety of devices, including many
	      brands of non-PostScript printers. By installing Ghostscript
	      and using a special text filter for your printer, you can make
	      your non-PostScript printer act like a real PostScript
	      printer.</para>
	    
	    <para>Ghostscript should be in the FreeBSD ports collection, if
	      you would like to install it from there. You can fetch, build,
	      and install it quite easily yourself, as well.</para>
	    
	    <para>To simulate PostScript, we have the text filter detect if it
	      is printing a PostScript file. If it is not, then the filter
	      will pass the file directly to the printer; otherwise, it will
	      use Ghostscript to first convert the file into a format the
	      printer will understand.</para>
	    
	    <para>Here is an example: the following script is a text filter
	      for Hewlett Packard DeskJet 500 printers. For other printers,
	      substitute the <option>-sDEVICE</option> argument to the</para>
	    
	    <para><citerefentry>
		<refentrytitle>gs</refentrytitle></citerefentry> (Ghostscript) command. (Type <command>gs -h</command> to get a list of devices the current installation of Ghostscript supports.)</para>

		<programlisting>
#!/bin/sh
#
#  ifhp - Print Ghostscript-simulated PostScript on a DeskJet 500
#  Installed in /usr/local/libexec/hpif

#
#  Treat LF as CR+LF:
#
printf "\033&amp;k2G" || exit 2

#
#  Read first two characters of the file
#
read first_line
first_two_chars=`expr "$first_line" : '\(..\)'`

if [ "$first_two_chars" = "%!" ]; then
    #
    #  It is PostScript; use Ghostscript to scan-convert and print it
    #
    /usr/local/bin/gs -dSAFER -dNOPAUSE -q -sDEVICE=djet500 -sOutputFile=- - \
        &amp;&amp; exit 0
else
    #
    #  Plain text or HP/PCL, so just print it directly; print a form
    #  at the end to eject the last page.
    #
    echo "$first_line" &amp;&amp; cat &amp;&amp; printf "\f" &amp;&amp; exit 0
fi

exit 2</programlisting>

	    <para>Finally, you need to notify LPD of the filter
	      via the <literal>if</literal> capability:</para>
	    
	      <programlisting>
:if=/usr/local/libexec/hpif:</programlisting>

	    <para>That is it. You can type <command>lpr plain.text</command> and <filename>lpr
		whatever.ps</filename> and both should print
	      successfully.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-convfilters">
	    <title>Conversion Filters</title>
	    
	    <para>After completing the simple setup described in <link
		linkend="printing-simple">Simple Printer Setup</link>, the
	      first thing you will probably want to do is install conversion
	      filters for your favorite file formats (besides plain ASCII
	      text).</para>
	    
	    
	    <sect4>
	      <title>Why Install Conversion Filters?</title>
	      
	      <para>Conversion filters make printing various kinds of files
		easy. As an example, suppose we do a lot of work with the TeX
		typesetting system, and we have a PostScript printer. Every
		time we generate a DVI file from TeX, we cannot print it
		directly until we convert the DVI file into PostScript. The
		command sequence goes like this:</para>
		
		<informalexample>
		  <screen>&prompt.user; <userinput>dvips seaweed-analysis.dvi</userinput>
&prompt.user; <userinput>lpr seaweed-analysis.ps</userinput></screen>
		</informalexample>

	      <para>By installing a conversion filter for DVI
		files, we can skip the hand conversion step each time by
		having LPD do it for us. Now, each time we get a DVI file, we
		are just one step away from printing it:</para>
	      
		<informalexample>
		  <screen>&prompt.user; <userinput>lpr -d seaweed-analysis.dvi</userinput></screen>
		</informalexample>

	      <para>We got LPD to do the DVI file conversion
		for us by specifying the <option>-d</option> option. Section
		<link
		  linkend="printing-lpr-options-format">Formatting and
		  Conversion Options</link> lists the conversion options.</para>
	      
	      <para>For each of the conversion options you want a printer to
		support, install a <emphasis>conversion filter</emphasis> and
		specify its pathname in <filename>/etc/printcap</filename>. A
		conversion filter is like the text filter for the simple
		printer setup (see section <link linkend="printing-textfilter">Installing the Text Filter</link>) except that instead of
		printing plain text, the filter converts the file into a
		format the printer can understand.</para>
	      
	    </sect4>
	    
	    <sect4>
	      <title>Which Conversions Filters Should I Install?</title>
	      
	      <para>You should install the conversion filters you expect to
		use. If you print a lot of DVI data, then a DVI conversion
		filter is in order. If you have got plenty of troff to print
		out, then you probably want a troff filter.</para>
	      
	      <para>The following table summarizes the filters that LPD works
		with, their capability entries for the
		<filename>/etc/printcap</filename> file, and how to invoke
		them with the <command>lpr</command> command:</para>

		<informaltable frame="none">
		  <tgroup cols="3">
		    <thead>
		      <row>
			<entry>File type</entry>
			<entry><filename>/etc/printcap</filename>
			  capability</entry>
			<entry><command>lpr</command> option</entry>
		      </row>
		    </thead>
		    <tbody>
		      <row>
			<entry>cifplot</entry>
			<entry><literal>cf</literal></entry>
			<entry><option>-c</option></entry>
		      </row>

		      <row>
			<entry>DVI</entry>
			<entry><literal>df</literal></entry>
			<entry><option>-d</option></entry>
		      </row>

		      <row>
			<entry>plot</entry>
			<entry><literal>gf</literal></entry>
			<entry><option>-g</option></entry>
		      </row>

		      <row>
			<entry>ditroff</entry>
			<entry><literal>nf</literal></entry>
			<entry><option>-n</option></entry>
		      </row>

		      <row>
			<entry>FORTRAN text</entry>
			<entry><literal>rf</literal></entry>
			<entry><option>-f</option></entry>
		      </row>

		      <row>
			<entry>troff</entry>
			<entry><literal>rf</literal></entry>
			<entry><option>-f</option></entry>
		      </row>

		      <row>
			<entry>raster</entry>
			<entry><literal>vf</literal></entry>
			<entry><option>-v</option></entry>
		      </row>

		      <row>
			<entry>plain text</entry>
			<entry><literal>if</literal></entry>
			<entry>none, <option>-p</option>, or <option>-l</option></entry>
		      </row>
		    </tbody>
		  </tgroup>
		</informaltable>
	      
	      <para>In our example, using <command>lpr -d</command> means the
		printer needs a <literal>df</literal> capability in
		its entry in <filename>/etc/printcap</filename>.</para>
	      
	      <para>Despite what others might contend, formats like FORTRAN
		text and plot are probably obsolete. At your site, you can
		give new meanings to these or any of the formatting options
		just by installing custom filters. For example, suppose you
		would like to directly print Printerleaf files (files from the
		Interleaf desktop publishing program), but will never print
		plot files. You could install a Printerleaf conversion filter
		under the <literal>gf</literal> capability and then
		educate your users that <command>lpr -g</command> mean &ldquo;print
		Printerleaf files.&rdquo;</para>
	      
	    </sect4>
	    
	    <sect4>
	      <title>Installing Conversion Filters</title>
	      
	      <para>Since conversion filters are programs you install outside
		of the base FreeBSD installation, they should probably go
		under <filename>/usr/local</filename>. The directory
		<filename>/usr/local/libexec</filename> is a popular location,
		since they are specialized programs that only LPD will run;
		regular users should not ever need to run them.</para>
	      
	      <para>To enable a conversion filter, specify its pathname under
		the appropriate capability for the destination printer in
		<filename>/etc/printcap</filename>.</para>
	      
	      <para>In our example, we will add the DVI conversion filter to
		the entry for the printer named <literal>bamboo</literal>. Here is the example
		<filename>/etc/printcap</filename> file again, with the new
		<literal>df</literal> capability for the printer
		<literal>bamboo</literal>.</para>

		<programlisting>
#
#  /etc/printcap for host rose - added df filter for bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>

	      <para>The DVI filter is a shell script named
		<filename>/usr/local/libexec/psdf</filename>. Here is that
		script:</para>

		<programlisting>
#!bin/sh
#
#  psdf - DVI to PostScript printer filter
#  Installed in /usr/local/libexec/psdf
#
# Invoked by lpd when user runs lpr -d
#
exec /usr/local/bin/dvips -f | /usr/local/libexec/lprps "$@"</programlisting>

	      <para>This script runs  <citerefentry>
		  <refentrytitle>dvips</refentrytitle></citerefentry> in filter mode (the <option>-f</option> argument) on standard input, which is the job to print. It then starts the PostScript printer filter <command>lprps</command> (see section <link linkend="printing-advanced-if-conversion">Accommodating Plain Text Jobs on PostScript
		  Printers</link>) with the arguments LPD passed to this script.
		<command>lprps</command> will use those arguments
		to account for the pages printed.</para>
	      
	    </sect4>
	    
	    <sect4>
	      <title>More Conversion Filter Examples</title>
	      
	      <para>Since there is no fixed set of steps to install
		conversion filters, let me instead provide more examples. Use
		these as guidance to making your own filters. Use them
		directly, if appropriate.</para>
	      
	      <para>This example script is a raster (well, GIF file, actually)
		conversion filter for a Hewlett Packard LaserJet III-Si
		printer:</para>

		<programlisting>
#!/bin/sh
#
#  hpvf - Convert GIF files into HP/PCL, then print
#  Installed in /usr/local/libexec/hpvf
		  
PATH=/usr/X11R6/bin:$PATH; export PATH giftopnm | ppmtopgm | pgmtopbm | pbmtolj -resolution 300 \
    &amp;&amp; exit 0 \
    || exit 2</programlisting>

	      <para>It works by converting the GIF file into a
		portable anymap, converting that into a portable graymap,
		converting that into a portable bitmap, and converting that
		into LaserJet/PCL-compatible data.</para>
	      
	      <para>Here is the <filename>/etc/printcap</filename> file with
		an entry for a printer using the above filter:</para>

		  <programlisting>
#
#  /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
        :lp=/dev/lpt0:sh:sd=/var/spool/lpd/teak:mx#0:\
        :if=/usr/local/libexec/hpif:\
        :vf=/usr/local/libexec/hpvf:</programlisting>
	      
	      <para>The following script is a conversion filter for troff data
		from the groff typesetting system for the PostScript printer
		named <literal>bamboo</literal>:</para>

		<programlisting>
#!/bin/sh
#
#  pstf - Convert groff's troff data into PS, then print.
#  Installed in /usr/local/libexec/pstf
#
exec grops | /usr/local/libexec/lprps "$@"</programlisting>
	      
	      <para>The above script makes use of <command>lprps</command> again to handle the communication
		with the printer. If the printer were on a parallel port, we
		would use this script instead:</para>

		<programlisting>
#!/bin/sh
#
#  pstf - Convert groff's troff data into PS, then print.
#  Installed in /usr/local/libexec/pstf
#
exec grops</programlisting>
	      
	      <para>That is it. Here is the entry we need to
		add to <filename>/etc/printcap</filename> to enable the
		filter:</para>
		
		<programlisting>
:tf=/usr/local/libexec/pstf:</programlisting>
	      
	      <para>Here is an example that might make old hands at FORTRAN
		blush. It is a FORTRAN-text filter for any printer that can
		directly print plain text. We will install it for the printer
		<literal>teak</literal>:</para>

		  <programlisting>
#!/bin/sh
#
# hprf - FORTRAN text filter for LaserJet 3si:
# Installed in /usr/local/libexec/hprf
#

printf "\033&amp;k2G" &amp;&amp; fpr &amp;&amp; printf "\f" &amp;&amp; exit 0
exit 2</programlisting>
	      
	      <para>And we will add this line to the
		<filename>/etc/printcap</filename> for the printer
		<literal>teak</literal> to enable this filter:</para>
	      
		<programlisting>
:rf=/usr/local/libexec/hprf:</programlisting>
	      
	      <para>Here is one final, somewhat complex example. We will add
		a DVI filter to the LaserJet printer <literal>teak</literal> introduced earlier. First, the
		easy part: updating <filename>/etc/printcap</filename> with
		the location of the DVI filter:</para>
	      
		<programlisting>
:df=/usr/local/libexec/hpdf:</programlisting>
	      
	      <para>Now, for the hard part: making the filter. For that, we
		need a DVI-to-LaserJet/PCL conversion program. The FreeBSD
		ports collection (see <link linkend="ports">The
		  Ports Collection</link>) has one: <citerefentry>
		  <refentrytitle>dvi2xx</refentrytitle></citerefentry> is the
		name of the package. Installing this package gives us the
		program we need, <citerefentry>
		  <refentrytitle>dvilj2p</refentrytitle></citerefentry>, which converts DVI into LaserJet IIp, LaserJet III, and LaserJet 2000 compatible codes.</para>
	      
	      <para><citerefentry>
		  <refentrytitle>dvilj2p</refentrytitle></citerefentry> makes
		the filter <command>hpdf</command> quite complex since
		<citerefentry>
		  <refentrytitle>dvilj2p</refentrytitle></citerefentry> cannot
		read from standard input. It wants to work with a filename.
		What is worse, the filename has to end in
		<filename>.dvi</filename> so using
		<filename>/dev/fd/0</filename> for standard input is
		problematic. We can get around that problem by linking
		(symbolically) a temporary file name (one that ends in
		<filename>.dvi</filename>) to <filename>/dev/fd/0</filename>,
		thereby forcing  <citerefentry>
		  <refentrytitle>dvilj2p</refentrytitle></citerefentry> to read from standard input.</para>
	      
	      <para>The only other fly in the ointment is the fact that we
		cannot use <filename>/tmp</filename> for the temporary link.
		Symbolic links are owned by user and group
		<username>bin</username>. The filter runs as user <username>daemon</username>. And the
		<filename>/tmp</filename> directory has the sticky bit set.
		The filter can create the link, but it will not be able clean
		up when done and remove it since the link will belong to a
		different user.</para>
	      
	      <para>Instead, the filter will make the symbolic link in the
		current working directory, which is the spooling directory
		(specified by the <literal>sd</literal> capability
		in <filename>/etc/printcap</filename>). This is a perfect
		place for filters to do their work, especially since there is
		(sometimes) more free disk space in the spooling directory
		than under <filename>/tmp</filename>.</para>
	      
	      <para>Here, finally, is the filter:</para>

		<programlisting>
#!/bin/sh
#
#  hpdf - Print DVI data on HP/PCL printer
#  Installed in /usr/local/libexec/hpdf

PATH=/usr/local/bin:$PATH; export PATH

#
#  Define a function to clean up our temporary files.  These exist
#  in the current directory, which will be the spooling directory
#  for the printer.
#
cleanup() {
   rm -f hpdf$$.dvi
}

#
#  Define a function to handle fatal errors: print the given message
#  and exit 2.  Exiting with 2 tells LPD to do not try to reprint the
#  job.
#
fatal() {
    echo "$@" 1&gt;&amp;2
    cleanup
    exit 2
}

#
#  If user removes the job, LPD will send SIGINT, so trap SIGINT
#  (and a few other signals) to clean up after ourselves.
#
trap cleanup 1 2 15 

#
#  Make sure we are not colliding with any existing files.
#
cleanup

#
#  Link the DVI input file to standard input (the file to print).
#
ln -s /dev/fd/0 hpdf$$.dvi || fatal "Cannot symlink /dev/fd/0"

#
#  Make LF = CR+LF
#
printf "\033&amp;k2G" || fatal "Cannot initialize printer"

# 
#  Convert and print.  Return value from dvilj2p does not seem to be
#  reliable, so we ignore it.
#
dvilj2p -M1 -q -e- dfhp$$.dvi

#
#  Clean up and exit
#
cleanup
exit 0</programlisting>
	      
	    </sect4>
	    
	    <sect4 id="printing-advanced-autoconv">
	      <title>Automated Conversion: An Alternative To Conversion
		Filters</title>
	      
	      <para>All these conversion filters accomplish a lot for your
		printing environment, but at the cost forcing the user to
		specify (on the  <citerefentry>
		  <refentrytitle>lpr</refentrytitle></citerefentry>
		command line) which one to use. If your users are not
		particularly computer literate, having to specify a filter
		option will become annoying. What is worse, though, is that
		an incorrectly specified filter option may run a filter on the
		wrong type of file and cause your printer to spew out hundreds
		of sheets of paper.</para>
	      
	      <para>Rather than install conversion filters at all, you might
		want to try having the text filter (since it is the default
		filter) detect the type of file it has been asked to print and
		then automatically run the right conversion filter. Tools
		such as <command>file</command> can be of help
		here. Of course, it will be hard to determine the differences
		between <emphasis>some</emphasis> file types&mdash;and, of course,
		you can still provide conversion filters just for them.</para>
	      
	      <para>The FreeBSD ports collection has a text filter that
		performs automatic conversion called  <citerefentry>
		  <refentrytitle>apsfilter</refentrytitle></citerefentry>. It can detect plain text, PostScript, and DVI files, run the proper conversions, and print.</para>
	      
	    </sect4>
	  </sect3>
	  
	  <sect3 id="printing-advanced-of">
	    <title>Output Filters</title>
	    
	    <para>The LPD spooling system supports one other type of filter
	      that we have not yet explored: an output filter. An output
	      filter is intended for printing plain text only, like the text
	      filter, but with many simplifications. If you are using an
	      output filter but no text filter, then:</para>
	      <itemizedlist>
		
		<listitem>
		  <para>LPD starts an output filter once for the entire job
		    instead of once for each file in the job.</para>
		</listitem>
		
		<listitem>
		  <para>LPD does not make any provision to identify the start
		    or the end of files within the job for the output filter.</para>
		</listitem>
		
		<listitem>
		  <para>LPD does not pass the user's login or host to the
		    filter, so it is not intended to do accounting. In fact,
		    it gets only two arguments:</para>
		    
		    <cmdsynopsis>
		      <command>filter-name</command>
		      <arg choice="plain">-w<replaceable>width</replaceable></arg>
		      <arg choice="plain">-l<replaceable>length</replaceable></arg>
		    </cmdsynopsis>

		<para>Where <replaceable>width</replaceable> is
		    from the <literal>pw</literal> capability and
		    <replaceable>length</replaceable> is from the <literal>pl</literal> capability for the printer in
		    question.</para>
		</listitem>
		
	      </itemizedlist>

	    
	    <para>Do not be seduced by an output filter's simplicity. If you
	      would like each file in a job to start on a different page an
	      output filter <emphasis>will not work</emphasis>. Use a text
	      filter (also known as an input filter); see section <link
		linkend="printing-textfilter">Installing the Text
		Filter</link>. Furthermore, an output filter is actually
	      <emphasis>more complex</emphasis> in that it has to examine the
	      byte stream being sent to it for special flag characters and
	      must send signals to itself on behalf of LPD.</para>
	    
	    <para>However, an output filter is <emphasis>necessary</emphasis>
	      if you want header pages and need to send escape sequences or
	      other initialization strings to be able to print the header
	      page. (But it is also <emphasis>futile</emphasis> if you want
	      to charge header pages to the requesting user's account, since
	      LPD does not give any user or host information to the output
	      filter.)</para>
	    
	    <para>On a single printer, LPD allows both an output filter and
	      text or other filters. In such cases, LPD will start the output
	      filter to print the header page (see section <link
		linkend="printing-advanced-header-pages">Header
		Pages</link>) only. LPD then expects the output filter to
	      <emphasis>stop itself</emphasis> by sending two bytes to the
	      filter: ASCII 031 followed by ASCII 001. When an output filter
	      sees these two bytes (031, 001), it should stop by sending
	      SIGSTOP to itself. When LPD's done running other filters, it
	      will restart the output filter by sending SIGCONT to it.</para>
	    
	    <para>If there is an output filter but <emphasis>no</emphasis>
	      text filter and LPD is working on a plain text job, LPD uses the
	      output filter to do the job. As stated before, the output
	      filter will print each file of the job in sequence with no
	      intervening form feeds or other paper advancement, and this is
	      probably <emphasis>not</emphasis> what you want. In almost all
	      cases, you need a text filter.</para>
	    
	    <para>The program <command>lpf</command>, which we
	      introduced earlier as a text filter, can also run as an output
	      filter. If you need a quick-and-dirty output filter but do not
	      want to write the byte detection and signal sending code, try
	      <command>lpf</command>. You can also wrap <command>lpf</command> in a shell script to handle any
	      initialization codes the printer might require.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-lpf">
	    <title><command>lpf</command>: a Text Filter</title>
	    
	    <para>The program <filename>/usr/libexec/lpr/lpf</filename> that
	      comes with FreeBSD binary distribution is a text filter (input
	      filter) that can indent output (job submitted with <command>lpr -i</command>), allow literal characters to pass
	      (job submitted with <command>lpr -l</command>), adjust the
	      printing position for backspaces and tabs in the job, and
	      account for pages printed. It can also act like an output
	      filter.</para>
	    
	    <para><command>lpf</command> is suitable for many
	      printing environments. And although it has no capability to
	      send initialization sequences to a printer, it is easy to write
	      a shell script to do the needed initialization and then execute
	      <command>lpf</command>.</para>
	    
	    <para>In order for <command>lpf</command> to do page
	      accounting correctly, it needs correct values filled in for the
	      <literal>pw</literal> and <literal>pl</literal> capabilities in the
	      <filename>/etc/printcap</filename> file. It uses these values
	      to determine how much text can fit on a page and how many pages
	      were in a user's job. For more information on printer
	      accounting, see <link
		linkend="printing-advanced-acct">Accounting for Printer
		Usage</link>.</para>
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-advanced-header-pages">
	  <title>Header Pages</title>
	  
	  <para>If you have <emphasis>lots</emphasis> of users, all of them
	    using various printers, then you probably want to consider
	    <emphasis>header pages</emphasis> as a necessary evil.</para>
	  
	  <para>Header pages, also known as <emphasis>banner</emphasis> or
	    <emphasis>burst pages</emphasis> identify to whom jobs belong
	    after they are printed. They are usually printed in large, bold
	    letters, perhaps with decorative borders, so that in a stack of
	    printouts they stand out from the real documents that comprise
	    users' jobs. They enable users to locate their jobs quickly. The
	    obvious drawback to a header page is that it is yet one more sheet
	    that has to be printed for every job, their ephemeral usefulness
	    lasting not more than a few minutes, ultimately finding themselves
	    in a recycling bin or rubbish heap. (Note that header pages go
	    with each job, not each file in a job, so the paper waste might
	    not be that bad.)</para>
	  
	  <para>The LPD system can provide header pages automatically for your
	    printouts <emphasis>if</emphasis> your printer can directly print
	    plain text. If you have a PostScript printer, you will need an
	    external program to generate the header page; see <link
	      linkend="printing-advanced-header-pages-ps">Header Pages
	      on    PostScript Printers</link>.</para>
	  
	  
	  <sect3 id="printing-advanced-header-pages-enabling">
	    <title>Enabling Header Pages</title>
	    
	    <para>In the <link linkend="printing-simple">Simple
		Printer        Setup</link>, we turned off header pages by
	      specifying <literal>sh</literal> (meaning &ldquo;suppress
	      header&rdquo;) in the <filename>/etc/printcap</filename> file. To
	      enable header pages for a printer, just remove the <literal>sh</literal> capability.</para>
	    
	    <para>Sounds too easy, right?</para>
	    
	    <para>You are right. You <emphasis>might</emphasis> have to
	      provide an output filter to send initialization strings to the
	      printer. Here is an example output filter for Hewlett Packard
	      PCL-compatible printers:</para>

		<programlisting>
#!/bin/sh
#
#  hpof - Output filter for Hewlett Packard PCL-compatible printers
#  Installed in /usr/local/libexec/hpof

printf "\033&amp;k2G" || exit 2 exec
/usr/libexec/lpr/lpf</programlisting>
	    
	    <para>Specify the path to the output filter in the
	      <literal>of</literal> capability. See <link
		linkend="printing-advanced-of">Output Filters</link> for more information.</para>
	    
	    <para>Here is an example <filename>/etc/printcap</filename> file
	      for the printer <literal>teak</literal> that we
	      introduced earlier; we enabled header pages and added the above
	      output filter:</para>

		<programlisting>
#
#  /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
        :lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:\
        :if=/usr/local/libexec/hpif:\
        :vf=/usr/local/libexec/hpvf:\
        :of=/usr/local/libexec/hpof:</programlisting>
	    
	    <para>Now, when users print jobs to <literal>teak</literal>, they get a header page with each
	      job. If users want to spend time searching for their printouts,
	      they can suppress header pages by submitting the job with
	      <command>lpr -h</command>; see <link
		linkend="printing-lpr-options-misc">Header Page
		Options</link> for more  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>
	      options.</para>

	    <note>
	      <para>LPD prints a form feed character after the header page.
		If your printer uses a different character or sequence of
		characters to eject a page, specify them with the <literal>ff</literal> capability in
		<filename>/etc/printcap</filename>.</para>
	    </note>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-header-pages-controlling">
	    <title>Controlling Header Pages</title>
	    
	    <para>By enabling header pages, LPD will produce a <emphasis>long
		header</emphasis>, a full page of large letters identifying
	      the user, host, and job. Here is an example (kelly printed the
	      job named outline from host rose):</para>
	    
	      <programlisting>
      k                   ll       ll
      k                    l        l
      k                    l        l
      k   k     eeee       l        l     y    y
      k  k     e    e      l        l     y    y
      k k      eeeeee      l        l     y    y
      kk k     e           l        l     y    y
      k   k    e    e      l        l     y   yy
      k    k    eeee      lll      lll     yyy y
                                               y
                                          y    y
                                           yyyy


                                   ll
                          t         l        i
                          t         l
       oooo    u    u   ttttt       l       ii     n nnn     eeee
      o    o   u    u     t         l        i     nn   n   e    e
      o    o   u    u     t         l        i     n    n   eeeeee
      o    o   u    u     t         l        i     n    n   e
      o    o   u   uu     t  t      l        i     n    n   e    e
       oooo     uuu u      tt      lll      iii    n    n    eeee









      r rrr     oooo     ssss     eeee
      rr   r   o    o   s    s   e    e
      r        o    o    ss      eeeeee
      r        o    o      ss    e
      r        o    o   s    s   e    e
      r         oooo     ssss     eeee







                                              Job:  outline
                                              Date: Sun Sep 17 11:04:58 1995</programlisting>

	    <para>LPD appends a form feed after this text so
	      the job starts on a new page (unless you have <literal>sf</literal> (suppress form feeds) in the
	      destination printer's entry in
	      <filename>/etc/printcap</filename>).</para>
	    
	    <para>If you prefer, LPD can make a <emphasis>short
		header</emphasis>; specify <literal>sb</literal>
	      (short banner) in the <filename>/etc/printcap</filename> file.
	      The header page will look like this:</para>
	    
	      <programlisting>
rose:kelly  Job: outline  Date: Sun Sep 17 11:07:51 1995</programlisting>

	    <para>Also by default, LPD prints the header page
	      first, then the job. To reverse that, specify <literal>hl</literal> (header last) in
	      <filename>/etc/printcap</filename>.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-header-pages-accounting">
	    <title>Accounting for Header Pages</title>
	    
	    <para>Using LPD's built-in header pages enforces a particular
	      paradigm when it comes to printer accounting: header pages must
	      be <emphasis>free of charge</emphasis>.</para>
	    
	    <para>Why?</para>
	    
	    <para>Because the output filter is the only external program that
	      will have control when the header page is printed that could do
	      accounting, and it is not provided with any <emphasis>user or
		host</emphasis> information or an accounting file, so it has
	      no idea whom to charge for printer use. It is also not enough
	      to just &ldquo;add one page&rdquo; to the text filter or any of the
	      conversion filters (which do have user and host information)
	      since users can suppress header pages with <command>lpr
		-h</command>. They could still be charged for header pages
	      they did not print. Basically, <command>lpr -h</command> will
	      be the preferred option of environmentally-minded users, but you
	      cannot offer any incentive to use it.</para>
	    
	    <para>It is <emphasis>still not enough</emphasis> to have each of
	      the filters generate their own header pages (thereby being able
	      to charge for them). If users wanted the option of suppressing
	      the header pages with <command>lpr -h</command>, they will still
	      get them and be charged for them since LPD does not pass any
	      knowledge of the <option>-h</option> option to any of the
	      filters.</para>
	    
	    <para>So, what are your options?</para>
	    
	    <para>You can:</para>
	      <itemizedlist>
		
		<listitem>
		  <para>Accept LPD's paradigm and make header pages free.</para>
		</listitem>
		
		<listitem>
		  <para>Install an alternative to LPD, such as LPDng or PLP.
		    Section <link linkend="printing-lpd-alternatives">Alternatives to the Standard   Spooler</link> tells
		    more about other spooling software you can substitute for
		    LPD.</para>
		</listitem>
		
		<listitem>
		  <para>Write a <emphasis>smart</emphasis> output filter.
		    Normally, an output filter is not meant to do anything
		    more than initialize a printer or do some simple character
		    conversion. It is suited for header pages and plain text
		    jobs (when there is no text (input) filter). But, if there
		    is a text filter for the plain text jobs, then LPD will
		    start the output filter only for the header pages. And
		    the output filter can parse the header page text that LPD
		    generates to determine what user and host to charge for
		    the header page. The only other problem with this method
		    is that the output filter still does not know what
		    accounting file to use (it is not passed the name of the
		    file from the <literal>af</literal>
		    capability), but if you have a well-known accounting file,
		    you can hard-code that into the output filter. To
		    facilitate the parsing step, use the <literal>sh</literal> (short header) capability in
		    <filename>/etc/printcap</filename>. Then again, all that
		    might be too much trouble, and users will certainly
		    appreciate the more generous system administrator who
		    makes header pages free.</para>
		</listitem>
		
	      </itemizedlist>

	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-header-pages-ps">
	    <title>Header Pages on PostScript Printers</title>
	    
	    <para>As described above, LPD can generate a plain text header
	      page suitable for many printers. Of course, PostScript cannot
	      directly print plain text, so the header page feature of LPD is
	      useless&mdash;or mostly so.</para>
	    
	    <para>One obvious way to get header pages is to have every
	      conversion filter and the text filter generate the header page.
	      The filters should should use the user and host arguments to
	      generate a suitable header page. The drawback of this method is
	      that users will always get a header page, even if they submit
	      jobs with <command>lpr -h</command>.</para>
	    
	    <para>Let us explore this method. The following script takes
	      three arguments (user login name, host name, and job name) and
	      makes a simple PostScript header page:</para>

	      <programlisting>
#!/bin/sh
#
#  make-ps-header - make a PostScript header page on stdout
#  Installed in /usr/local/libexec/make-ps-header
#

#
#  These are PostScript units (72 to the inch).  Modify for A4 or
#  whatever size paper you are using:
#
page_width=612
page_height=792
border=72

#
#  Check arguments
#
if [ $# -ne 3 ]; then
    echo "Usage: `basename $0` &lt;user&gt; &lt;host&gt; &lt;job&gt;" 1&gt;&amp;2
    exit 1
fi

#
#  Save these, mostly for readability in the PostScript, below.
#
user=$1
host=$2
job=$3
date=`date`

#
#  Send the PostScript code to stdout.
#
exec cat &lt;&lt;EOF
%!PS

%
%  Make sure we do not interfere with user's job that will follow
%
save

%
%  Make a thick, unpleasant border around the edge of the paper.
%
$border $border moveto
$page_width $border 2 mul sub 0 rlineto
0 $page_height $border 2 mul sub rlineto
currentscreen 3 -1 roll pop 100 3 1 roll setscreen
$border 2 mul $page_width sub 0 rlineto closepath
0.8 setgray 10 setlinewidth stroke 0 setgray

%
%  Display user's login name, nice and large and prominent
%
/Helvetica-Bold findfont 64 scalefont setfont
$page_width ($user) stringwidth pop sub 2 div $page_height 200 sub moveto
($user) show

%
%  Now show the boring particulars
%
/Helvetica findfont 14 scalefont setfont
/y 200 def
[ (Job:) (Host:) (Date:) ] {
200 y moveto show /y y 18 sub def }
forall

/Helvetica-Bold findfont 14 scalefont setfont
/y 200 def
[ ($job) ($host) ($date) ] {
        270 y moveto show /y y 18 sub def
} forall

%
% That is it
%
restore
showpage
EOF</programlisting>

	    <para>Now, each of the conversion filters and the
	      text filter can call this script to first generate the header
	      page, and then print the user's job. Here is the DVI conversion
	      filter from earlier in this document, modified to make a header
	      page:</para>

	      <programlisting>
#!/bin/sh
#
#  psdf - DVI to PostScript printer filter
#  Installed in /usr/local/libexec/psdf
#
#  Invoked by lpd when user runs lpr -d
#
		
orig_args="$@"

fail() {
    echo "$@" 1&gt;&amp;2
    exit 2
}

while getopts "x:y:n:h:" option; do
    case $option in
        x|y)  ;; # Ignore
        n)    login=$OPTARG ;;
        h)    host=$OPTARG ;;
        *)    echo "LPD started `basename $0` wrong." 1&gt;&amp;2
              exit 2
              ;;
    esac
done

[ "$login" ] || fail "No login name"
[ "$host" ] || fail "No host name"

( /usr/local/libexec/make-ps-header $login $host "DVI File"
  /usr/local/bin/dvips -f ) | eval /usr/local/libexec/lprps $orig_args</programlisting>

	    <para>Notice how the filter has to parse the
	      argument list in order to determine the user and host name. The
	      parsing for the other conversion filters is identical. The text
	      filter takes a slightly different set of arguments, though (see
	      section <link linkend="printing-advanced-filters">How      Filters Work</link>).</para>
	    
	    <para>As we have mentioned before, the above scheme, though fairly
	      simple, disables the &ldquo;suppress header page&rdquo; option (the
	      <option>-h</option> option) to <command>lpr</command>. If users wanted to save a tree (or a
	      few pennies, if you charge for header pages), they would not be
	      able to do so, since every filter's going to print a header page
	      with every job.</para>
	    
	    <para>To allow users to shut off header pages on a per-job basis,
	      you will need to use the trick introduced in section
	      <link linkend="printing-advanced-header-pages-accounting">Accounting for Header Pages</link>: write an output filter
	      that parses the LPD-generated header page and produces a
	      PostScript version. If the user submits the job with
	      <command>lpr -h</command>, then LPD will not generate a header
	      page, and neither will your output filter. Otherwise, your
	      output filter will read the text from LPD and send the
	      appropriate header page PostScript code to the printer.</para>
	    
	    <para>If you have a PostScript printer on a serial line, you can
	      make use of <command>lprps</command>, which comes
	      with an output filter, <command>psof</command>, which
	      does the above. Note that <command>psof</command>
	      does not charge for header pages.</para>
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-advanced-network-printers">
	  <title>Networked Printing</title>
	  
	  <para>FreeBSD supports networked printing: sending jobs to remote
	    printers. Networked printing generally refers to two different
	    things:</para>
	    <itemizedlist>
	      
	      <listitem>
		<para>Accessing a printer attached to a remote host. You
		  install a printer that has a conventional serial or parallel
		  interface on one host. Then, you set up LPD to enable
		  access to the printer from other hosts on the network.
		  Section <link
		    linkend="printing-advanced-network-rm">Printers
		    Installed on Remote Hosts</link> tells how to do this.</para>
	      </listitem>
	      
	      <listitem>
		<para>Accessing a printer attached directly to a network. The
		  printer has a network interface in addition (or in place of)
		  a more conventional serial or parallel interface. Such a
		  printer might work as follows:</para>
		  
		  <itemizedlist>
		    
		    <listitem>
		      <para>It might understand the LPD protocol and can even
			queue jobs from remote hosts. In this case, it acts
			just like a regular host running LPD. Follow the same
			procedure in section <link
			  linkend="printing-advanced-network-rm">Printers     Installed on Remote Hosts</link> to
			set up such a printer.</para>
		    </listitem>
		    
		    <listitem>
		      <para>It might support a data stream network connection.
			In this case, you &ldquo;attach&rdquo; the printer to one host
			on the network by making that host responsible for
			spooling jobs and sending them to the printer.
			Section <link
			  linkend="printing-advanced-network-net-if">Printers     with Networked Data Stream
			  Interfaces</link> gives some suggestions on installing
			such printers.</para>
		    </listitem>
		    
		  </itemizedlist>

	      </listitem>
	      
	    </itemizedlist>

	  
	  
	  <sect3 id="printing-advanced-network-rm">
	    <title>Printers Installed on Remote Hosts</title>
	    
	    <para>The LPD spooling system has built-in support for sending
	      jobs to other hosts also running LPD (or are compatible with
	      LPD). This feature enables you to install a printer on one host
	      and make it accessible from other hosts. It also works with
	      printers that have network interfaces that understand the LPD
	      protocol.</para>
	    
	    <para>To enable this kind of remote printing, first install a
	      printer on one host, the <emphasis>printer host</emphasis>,
	      using the simple printer setup described in <link
		linkend="printing-simple">Simple Printer Setup</link>. Do
	      any advanced setup in <link linkend="printing-advanced">Advanced Printer Setup</link> that you need. Make sure to
	      test the printer and see if it works with the features of LPD
	    you have enabled. Also ensure that the <emphasis>local
	      host</emphasis> has authorization to use the LPD service in the
	    <emphasis>remote host</emphasis> (see <link
	      linkend="printing-advanced-restricting-remote">Restricting Jobs
	      from Remote Printers</link>).</para>
	    
	    <para>If you are using a printer with a network interface that is
	      compatible with LPD, then the <emphasis>printer host</emphasis>
	      in the discussion below is the printer itself, and the
	      <emphasis>printer name</emphasis> is the name you configured for
	      the printer. See the documentation that accompanied your
	      printer and/or printer-network interface.</para>
	    
	    <para>Then, on the other hosts you want to have access to the
	      printer, make an entry in their
	      <filename>/etc/printcap</filename> files with the following:</para>
	      <orderedlist>
		
		<listitem>
		  <para>Name the entry anything you want. For simplicity,
		    though, you probably want to use the same name and aliases
		    as on the printer host.</para>
		</listitem>
		
		<listitem>
		  <para>Leave the <literal>lp</literal> capability
		    blank, explicitly (<literal>:lp=:</literal>).</para>
		</listitem>
		
		<listitem>
		  <para>Make a spooling directory and specify its location in
		    the <literal>sd</literal> capability. LPD will
		    store jobs here before they get sent to the printer host.</para>
		</listitem>
		
		<listitem>
		  <para>Place the name of the printer host in the <literal>rm</literal> capability.</para>
		</listitem>
		
		<listitem>
		  <para>Place the printer name on the <emphasis>printer
		      host</emphasis> in the <literal>rp</literal>
		    capability.</para>
		</listitem>
		
	      </orderedlist>

	    <para>That is it. You do not need to list conversion
	      filters, page dimensions, or anything else in the
	      <filename>/etc/printcap</filename> file.</para>
	    
	    <para>Here is an example. The host <hostid>rose</hostid> has two printers,
	      <literal>bamboo</literal> and <literal>rattan</literal>. We will enable users on the host
	      orchid to print to those printers. Here is the
	      <filename>/etc/printcap</filename> file for <hostid>orchid</hostid> (back from
	      section
	      <link linkend="printing-advanced-header-pages-enabling">Enabling Header Pages</link>). It already had the entry for
	      the printer <literal>teak</literal>; we have added
	      entries for the two printers on the host rose:</para>
	      
	      <programlisting>
#
#  /etc/printcap for host orchid - added (remote) printers on rose
#

#
#  teak is local; it is connected directly to orchid:
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
        :lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:\
        :if=/usr/local/libexec/ifhp:\
        :vf=/usr/local/libexec/vfhp:\
        :of=/usr/local/libexec/ofhp:

#
#  rattan is connected to rose; send jobs for rattan to rose:
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :lp=:rm=rose:rp=rattan:sd=/var/spool/lpd/rattan:

#
#  bamboo is connected to rose as well:
#
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :lp=:rm=rose:rp=bamboo:sd=/var/spool/lpd/bamboo:</programlisting>

	    <para>Then, we just need to make spooling
	      directories on <hostid>orchid</hostid>:</para>
	      
	      <informalexample>
		<screen>&prompt.root; <userinput>mkdir -p /var/spool/lpd/rattan /var/spool/lpd/bamboo</userinput>
&prompt.root; <userinput>chmod 770 /var/spool/lpd/rattan /var/spool/lpd/bamboo</userinput>
&prompt.root; <userinput>chown daemon.daemon /var/spool/lpd/rattan /var/spool/lpd/bamboo</userinput></screen>
	      </informalexample>
	    
	    <para>Now, users on <hostid>orchid</hostid> can print to
	      <literal>rattan</literal> and <literal>bamboo</literal>. If, for example, a user on orchid
	      typed
	      
	      <informalexample>
		<screen>&prompt.user; <userinput>lpr -P bamboo -d sushi-review.dvi</userinput></screen>
	      </informalexample> the LPD system on orchid would copy the job
	      to the spooling directory
	      <filename>/var/spool/lpd/bamboo</filename> and note that it was
	      a DVI job. As soon as the host rose has room in its <hostid>bamboo</hostid> spooling directory, the two LPDs
	      would transfer the file to rose. The file would wait in rose's
	      queue until it was finally printed. It would be converted from
	      DVI to PostScript (since bamboo is a PostScript printer) on
	      rose.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-network-net-if">
	    <title>Printers with Networked Data Stream Interfaces</title>
	    
	    <para>Often, when you buy a network interface card for a printer,
	      you can get two versions: one which emulates a spooler (the more
	      expensive version), or one which just lets you send data to it
	      as if you were using a serial or parallel port (the cheaper
	      version). This section tells how to use the cheaper version.
	      For the more expensive one, see the previous section <link
		linkend="printing-advanced-network-rm">Printers
		Installed on Remote Hosts</link>.</para>
	    
	    <para>The format of the <filename>/etc/printcap</filename> file
	      lets you specify what serial or parallel interface to use, and
	      (if you are using a serial interface), what baud rate, whether
	      to use flow control, delays for tabs, conversion of newlines,
	      and more. But there is no way to specify a connection to a
	      printer that is listening on a TCP/IP or other network
	      port.</para>
	    
	    <para>To send data to a networked printer, you need to develop a
	      communications program that can be called by the text and
	      conversion filters. Here is one such example: the script
	      <command>netprint</command> takes all data on
	      standard input and sends it to a network-attached printer. We
	      specify the hostname of the printer as the first argument and
	      the port number to which to connect as the second argument to
	      <command>netprint</command>. Note that this supports
	      one-way communication only (FreeBSD to printer); many network
	      printers support two-way communication, and you might want to
	      take advantage of that (to get printer status, perform
	      accounting, etc.).</para>

	      <programlisting>
#!/usr/bin/perl
#
#  netprint - Text filter for printer attached to network
#  Installed in /usr/local/libexec/netprint
#
$#ARGV eq 1 || die "Usage: $0 &lt;printer-hostname&gt; &lt;port-number&gt;";

$printer_host = $ARGV[0];
$printer_port = $ARGV[1];

require 'sys/socket.ph';

($ignore, $ignore, $protocol) = getprotobyname('tcp');
($ignore, $ignore, $ignore, $ignore, $address)
    = gethostbyname($printer_host);

$sockaddr = pack('S n a4 x8', &amp;AF_INET, $printer_port, $address);

socket(PRINTER, &amp;PF_INET, &amp;SOCK_STREAM, $protocol)
    || die "Can't create TCP/IP stream socket: $!";
connect(PRINTER, $sockaddr) || die "Can't contact $printer_host: $!";
while (&lt;STDIN&gt;) { print PRINTER; }
exit 0;</programlisting>
	    
	    <para>We can then use this script in various
	      filters. Suppose we had a Diablo 750-N line printer connected
	      to the network. The printer accepts data to print on port
	      number 5100. The host name of the printer is scrivener. Here
	      is the text filter for the printer:</para>

	      <programlisting>
#!/bin/sh
#
#  diablo-if-net - Text filter for Diablo printer `scrivener' listening
#  on port 5100.   Installed in /usr/local/libexec/diablo-if-net # exec
/usr/libexec/lpr/lpf "$@" | /usr/local/libexec/netprint scrivener 5100</programlisting>
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-advanced-restricting">
	  <title>Restricting Printer Usage</title>
	  
	  <para>This section gives information on restricting printer usage.
	    The LPD system lets you control who can access a printer, both
	    locally or remotely, whether they can print multiple copies, how
	    large their jobs can be, and how large the printer queues can
	    get.</para>
	  
	  
	  <sect3 id="printing-advanced-restricting-copies">
	    <title>Restricting Multiple Copies</title>
	    
	    <para>The LPD system makes it easy for users to print multiple
	      copies of a file. Users can print jobs with <command>lpr
		-#5</command> (for example) and get five copies of each file
	      in the job. Whether this is a good thing is up to you.</para>
	    
	    <para>If you feel multiple copies cause unnecessary wear and tear
	      on your printers, you can disable the <option>-#</option> option
	      to  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry> by
	      adding the <literal>sc</literal> capability to the
	      <filename>/etc/printcap</filename> file. When users submit jobs
	      with the <option>-#</option> option, they will see:</para>
	      
	      <informalexample>
		<screen>lpr: multiple copies are not allowed</screen>
	      </informalexample>
	    
	    <para>Note that if you have set up access to a printer remotely
	      (see section <link linkend="printing-advanced-network-rm">Printers Installed on Remote      Hosts</link>), you need
	      the <literal>sc</literal> capability on the remote
	      <filename>/etc/printcap</filename> files as well, or else users
	      will still be able to submit multiple-copy jobs by using another
	      host.</para>
	    
	    <para>Here is an example. This is the
	      <filename>/etc/printcap</filename> file for the host <hostid>rose</hostid>. The
	      printer <literal>rattan</literal> is quite hearty, so
	      we will allow multiple copies, but the laser printer <literal>bamboo</literal>'s a bit more delicate, so we will
	      disable multiple copies by adding the <literal>sc</literal> capability:</para>

	      <programlisting>
#
#  /etc/printcap for host rose - restrict multiple copies on bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:sc:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>
	    
	    <para>Now, we also need to add the <literal>sc</literal> capability on the host <hostid>orchid</hostid>'s
	      <filename>/etc/printcap</filename> (and while we are at it, let
	      us disable multiple copies for the printer <literal>teak</literal>):</para>

	      <programlisting>
#
#  /etc/printcap for host orchid - no multiple copies for local
#  printer teak or remote printer bamboo
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
        :lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:sc:\
        :if=/usr/local/libexec/ifhp:\
        :vf=/usr/local/libexec/vfhp:\
        :of=/usr/local/libexec/ofhp:

rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :lp=:rm=rose:rp=rattan:sd=/var/spool/lpd/rattan:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :lp=:rm=rose:rp=bamboo:sd=/var/spool/lpd/bamboo:sc:</programlisting>
	    
	    <para>By using the <literal>sc</literal>
	      capability, we prevent the use of <command>lpr -#</command>, but
	      that still does not prevent users from running  <citerefentry>
		<refentrytitle>lpr</refentrytitle></citerefentry>
	      multiple times, or from submitting the same file multiple times
	      in one job like this:</para>
	      
	      <informalexample>
		<screen>&prompt.user; <userinput>lpr forsale.sign forsale.sign forsale.sign forsale.sign forsale.sign</userinput></screen>
	      </informalexample>

	    <para>There are many ways to prevent this abuse
	      (including ignoring it) which you are free to explore.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-restricting-access">
	    <title>Restricting Access To Printers</title>
	    
	    <para>You can control who can print to what printers by using the
	      UNIX group mechanism and the <literal>rg</literal>
	      capability in <filename>/etc/printcap</filename>. Just place
	      the users you want to have access to a printer in a certain
	      group, and then name that group in the <literal>rg</literal> capability.</para>
	    
	    <para>Users outside the group (including root) will be greeted
	      with
	      
	      <errorname>
		lpr: Not a member of the restricted group
	      </errorname>

	      if they try to print to the controlled
	      printer.</para>
	    
	    <para>As with the <literal>sc</literal> (suppress
	      multiple copies) capability, you need to specify <literal>rg</literal> on remote hosts that also have access
	      to your printers, if you feel it is appropriate (see section
	      <link linkend="printing-advanced-network-rm">Printers Installed on Remote Hosts</link>).</para>
	    
	    <para>For example, we will let anyone access the printer
	      <literal>rattan</literal>, but only those in group
	      <literal>artists</literal> can use <literal>bamboo</literal>. Here is the familiar
	      <filename>/etc/printcap</filename> for host <hostid>rose</hostid>:</para>

	      <programlisting>
#
#  /etc/printcap for host rose - restricted group for bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:

bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>

	    <para>Let us leave the other example
	      <filename>/etc/printcap</filename> file (for the host <hostid>orchid</hostid>)
	      alone. Of course, anyone on <hostid>orchid</hostid> can print to
	      <literal>bamboo</literal>. It might be the case that we only
	      allow certain logins on <hostid>orchid</hostid> anyway, and want them to have
	      access to the printer. Or not.</para>

	    <note>
	      <para>There can be only one restricted group per printer.</para>
	    </note>
	  </sect3>
	  
	  <sect3 id="printing-advanced-restricting-sizes">
	    <title>Controlling Sizes of Jobs Submitted</title>
	    
	    <para>If you have many users accessing the printers, you probably
	      need to put an upper limit on the sizes of the files users can
	      submit to print. After all, there is only so much free space on
	      the filesystem that houses the spooling directories, and you
	      also need to make sure there is room for the jobs of other
	      users.</para>
	    
	    <para>LPD enables you to limit the maximum byte size a file in a
	      job can be with the <literal>mx</literal> capability.
	      The units are in BUFSIZ blocks, which are 1024 bytes. If you
	      put a zero for this capability, there will be no limit on file
	      size.</para>

	    <note>
	      <para>The limit applies to <emphasis>files</emphasis> in a job,
		and <emphasis>not</emphasis> the total job size.</para>
	    </note>
	    
	    <para>LPD will not refuse a file that is larger than the limit you
	      place on a printer. Instead, it will queue as much of the file
	      up to the limit, which will then get printed. The rest will be
	      discarded. Whether this is correct behavior is up for
	      debate.</para>
	    
	    <para>Let us add limits to our example printers
	      <literal>rattan</literal> and <literal>bamboo</literal>. Since those artists' PostScript
	      files tend to be large, we will limit them to five megabytes.
	      We will put no limit on the plain text line printer:</para>

	      <programlisting>
#
#  /etc/printcap for host rose
#

#
#  No limit on job size:
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
        :sh:sd=/var/spool/lpd/rattan:\
        :lp=/dev/lpt0:\
        :if=/usr/local/libexec/if-simple:

#
#  Limit of five megabytes:
#
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:mx#5000:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>

	    <para>Again, the limits apply to the local users
	      only. If you have set up access to your printers remotely,
	      remote users will not get those limits. You will need to
	      specify the <literal>mx</literal> capability in the
	      remote <filename>/etc/printcap</filename> files as well. See
	      section <link
		linkend="printing-advanced-network-rm">Printers
		Installed      on Remote Hosts</link> for more information on
	      remote printing.</para>
	    
	    <para>There is another specialized way to limit job sizes from
	      remote printers; see section <link
		linkend="printing-advanced-restricting-remote">Restricting Jobs from Remote Printers</link>.</para>
	    
	  </sect3>
	  
	  <sect3 id="printing-advanced-restricting-remote">
	    <title>Restricting Jobs from Remote Printers</title>
	    
	    <para>The LPD spooling system provides several ways to restrict
	      print jobs submitted from remote hosts:</para>
	    
	    
	      <variablelist>
		<varlistentry><term>Host restrictions</term>
		  <listitem>
		    <para>You can control from which remote hosts a local LPD
		      accepts requests with the files
		      <filename>/etc/hosts.equiv</filename> and
		      <filename>/etc/hosts.lpd</filename>. LPD checks to see
		      if an incoming request is from a host listed in either
		      one of these files. If not, LPD refuses the
		      request.</para>
		    
		    <para>The format of these files is simple: one host name
		      per line. Note that the file
		      <filename>/etc/hosts.equiv</filename> is also used by
		      the
		      <citerefentry><refentrytitle>ruserok</refentrytitle><manvolnum>3</manvolnum></citerefentry> protocol, and affects programs like  <citerefentry>
			<refentrytitle>rsh</refentrytitle></citerefentry> and
		      <citerefentry>
			<refentrytitle>rcp</refentrytitle></citerefentry>, so be careful.</para>
		    
		    <para>For example, here is the
		      <filename>/etc/hosts.lpd</filename> file on the host
		    <hostid>rose</hostid>:</para>

		      <programlisting>
orchid
violet
madrigal.fishbaum.de</programlisting>
		    
		    <para>This means <hostid>rose</hostid> will accept requests
		    from the hosts <hostid>orchid</hostid>,
		    <hostid>violet</hostid>, and <hostid role="fqdn">madrigal.fishbaum.de</hostid>.
		    If any other host tries to access <hostid>rose</hostid>'s LPD, LPD will
		      refuse them.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>Size restrictions</term>
		  
		  <listitem>
		    <para>You can control how much free space there needs to
		      remain on the filesystem where a spooling directory
		      resides. Make a file called
		      <filename>minfree</filename> in the spooling directory
		      for the local printer. Insert in that file a number
		      representing how many disk blocks (512 bytes) of free
		      space there has to be for a remote job to be
		      accepted.</para>
		    
		    <para>This lets you insure that remote users will not fill
		      your filesystem. You can also use it to give a certain
		      priority to local users: they will be able to queue jobs
		      long after the free disk space has fallen below the
		      amount specified in the <filename>minfree</filename>
		      file.</para>
		    
		    <para>For example, let us add a
		      <filename>minfree</filename> file for the printer
		      <hostid>bamboo</hostid>. We examine
		      <filename>/etc/printcap</filename> to find the spooling
		      directory for this printer; here is
		    <hostid>bamboo</hostid>'s entry:</para>
		  
		      <programlisting>
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:mx#5000:\
        :lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:mx#5000:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>

		  <para>The spooling directory is the given
		      in the <literal>sd</literal> capability. We
		      will make three megabytes (which is 6144 disk blocks)
		      the amount of free disk space that must exist on the
		      filesystem for LPD to accept remote jobs:</para>
		  
		      <informalexample>
			<screen>&prompt.root; <userinput>echo 6144 &gt; /var/spool/lpd/bamboo/minfree</userinput></screen>
		      </informalexample>
		    
		  </listitem>
		</varlistentry>
		
		<varlistentry><term>User restrictions</term>
		  
		  <listitem>
		    <para>You can control which remote users can print to
		      local printers by specifying the <literal>rs</literal> capability in
		      <filename>/etc/printcap</filename>. When <literal>rs</literal> appears in the entry for a
		      locally-attached printer, LPD will accept jobs from
		      remote hosts <emphasis>if</emphasis> the user submitting
		      the job also has an account of the same login name on
		      the local host. Otherwise, LPD refuses the job.</para>
		    
		    <para>This capability is particularly useful in an
		      environment where there are (for example) different
		      departments sharing a network, and some users transcend
		      departmental boundaries. By giving them accounts on
		      your systems, they can use your printers from their own
		      departmental systems. If you would rather allow them to
		      use <emphasis>only</emphasis> your printers and not your
		      compute resources, you can give them &ldquo;token&rdquo; accounts,
		      with no home directory and a useless shell like
		      <filename>/usr/bin/false</filename>.</para>
		    
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    
	  </sect3>
	</sect2>
	
	<sect2 id="printing-advanced-acct">
	  <title>Accounting for Printer Usage</title>
	  
	  <para>So, you need to charge for printouts. And why not? Paper
	    and ink cost money. And then there are maintenance
	    costs&mdash;printers are loaded with moving parts and tend to break
	    down. You have examined your printers, usage patterns, and
	    maintenance fees and have come up with a per-page (or per-foot,
	    per-meter, or per-whatever) cost. Now, how do you actually start
	    accounting for printouts?</para>
	  
	  <para>Well, the bad news is the LPD spooling system does not provide
	    much help in this department. Accounting is highly dependent on
	    the kind of printer in use, the formats being printed, and
	    <emphasis>your</emphasis> requirements in charging for printer
	    usage.</para>
	  
	  <para>To implement accounting, you have to modify a printer's text
	    filter (to charge for plain text jobs) and the conversion filters
	    (to charge for other file formats), to count pages or query the
	    printer for pages printed. You cannot get away with using the
	    simple output filter, since it cannot do accounting. See section
	    <link
	      linkend="printing-advanced-filter-intro">Filters</link>.</para>
	  
	  <para>Generally, there are two ways to do accounting:</para>
	    <itemizedlist>
	      
	      <listitem>
		<para><emphasis>Periodic accounting</emphasis> is the more
		  common way, possibly because it is easier. Whenever someone
		  prints a job, the filter logs the user, host, and number of
		  pages to an accounting file. Every month, semester, year,
		  or whatever time period you prefer, you collect the
		  accounting files for the various printers, tally up the
		  pages printed by users, and charge for usage. Then you
		  truncate all the logging files, starting with a clean slate
		  for the next period.</para>
	      </listitem>
	      
	      <listitem>
		<para><emphasis>Timely accounting</emphasis> is less common,
		  probably because it is more difficult. This method has the
		  filters charge users for printouts as soon as they use the
		  printers. Like disk quotas, the accounting is immediate.
		  You can prevent users from printing when their account goes
		  in the red, and might provide a way for users to check and
		  adjust their &ldquo;print quotas.&rdquo; But this method requires some
		  database code to track users and their quotas.</para>
	      </listitem>
	      
	    </itemizedlist>

	  
	  <para>The LPD spooling system supports both methods easily: since
	    you have to provide the filters (well, most of the time), you also
	    have to provide the accounting code. But there is a bright side:
	    you have enormous flexibility in your accounting methods. For
	    example, you choose whether to use periodic or timely accounting.
	    You choose what information to log: user names, host names, job
	    types, pages printed, square footage of paper used, how long the
	    job took to print, and so forth. And you do so by modifying the
	    filters to save this information.</para>
	  
	  
	  <sect3>
	    <title>Quick and Dirty Printer Accounting</title>
	    
	    <para>FreeBSD comes with two programs that can get you set up
	      with simple periodic accounting right away. They are the text
	      filter <command>lpf</command>, described in section
	      <link linkend="printing-advanced-lpf">lpf: a Text
		Filter</link>, and <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>, a
	      program to gather and total entries from printer accounting
	      files.</para>
	    
	    <para>As mentioned in the section on filters (<link
		linkend="printing-advanced-filters">Filters</link>), LPD
	      starts the text and the conversion filters with the name of the
	      accounting file to use on the filter command line. The filters
	      can use this argument to know where to write an accounting file
	      entry. The name of this file comes from the <literal>af</literal> capability in
	      <filename>/etc/printcap</filename>, and if not specified as an
	      absolute path, is relative to the spooling directory.</para>
	    
	    <para>LPD starts <command>lpf</command> with page width
	      and length arguments (from the <literal>pw</literal>
	      and <literal>pl</literal> capabilities). <command>lpf</command> uses these arguments to determine how
	      much paper will be used. After sending the file to the printer,
	      it then writes an accounting entry in the accounting file. The
	      entries look like this:</para>

	      <programlisting>
2.00 rose:andy
3.00 rose:kelly
3.00 orchid:mary
5.00 orchid:mary
2.00 orchid:zhang</programlisting>
	    
	    <para>You should use a separate accounting file for
	      each printer, as <command>lpf</command> has no file
	      locking logic built into it, and two <command>lpf</command>s might corrupt each other's entries if
	      they were to write to the same file at the same time. A easy way
	      to insure a separate accounting file for each printer is to use
	      <literal>af=acct</literal> in
	      <filename>/etc/printcap</filename>. Then, each accounting file
	      will be in the spooling directory for a printer, in a file named
	      <filename>acct</filename>.</para>
	    
	    <para>When you are ready to charge users for printouts, run
	      the <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>
	      program. Just change to the spooling directory for the printer
	      you want to collect on and type  <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>. You
	      will get a dollar-centric summary like the following:</para>
	    
	      <informalexample>
		<screen>  Login               pages/feet   runs    price
orchid:kelly                5.00    1   $  0.10
orchid:mary                31.00    3   $  0.62
orchid:zhang                9.00    1   $  0.18
rose:andy                   2.00    1   $  0.04
rose:kelly                177.00  104   $  3.54
rose:mary                  87.00   32   $  1.74
rose:root                  26.00   12   $  0.52

total                     337.00  154   $  6.74</screen>
	      </informalexample>

	    <para>These are the arguments  <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>
	      expects:</para>
	    
	      <variablelist>
		<varlistentry><term><option>-P<replaceable>printer</replaceable></option></term>
		  <listitem>
		    <para>Which <replaceable>printer</replaceable> to
		      summarize. This option works only if there is an
		      absolute path in the <literal>af</literal>
		      capability in <filename>/etc/printcap</filename>.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-c</option></term>
		  
		  <listitem>
		    <para>Sort the output by cost instead of alphabetically by
		      user name.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-m</option></term>
		  
		  <listitem>
		    <para>Ignore host name in the accounting files. With this
		    option, user <username>smith</username> on host <hostid>alpha</hostid> is the same user <username>smith</username>
		    on host <hostid>gamma</hostid>. Without, they are different
		      users.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-p<replaceable>price</replaceable></option></term>
		  
		  <listitem>
		    <para>Compute charges with <replaceable>price</replaceable> dollars per page or per foot
		      instead of the price from the <literal>pc</literal> capability in
		      <filename>/etc/printcap</filename>, or two cents (the
		      default). You can specify <replaceable>price</replaceable> as a floating point
		      number.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-r</option></term>
		  
		  <listitem>
		    <para>Reverse the sort order.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><option>-s</option></term>
		  
		  <listitem>
		    <para>Make an accounting summary file and truncate the
		      accounting file.</para>
		  </listitem>
		</varlistentry>
		
		<varlistentry><term><replaceable>name</replaceable> <replaceable>&hellip;</replaceable></term>
		  
		  <listitem>
		    <para>Print accounting information for the given user
		      <replaceable>names</replaceable> only.</para>
		    
		  </listitem>
		</varlistentry>
	      </variablelist>
	    
	    <para>In the default summary that  <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>
	      produces, you see the number of pages printed by each user from
	      various hosts. If, at your site, host does not matter (because
	      users can use any host), run <command>pac -m</command>, to
	      produce the following summary:</para>
	    
	      <informalexample>
		<screen>  Login               pages/feet   runs    price
andy                        2.00    1   $  0.04
kelly                     182.00  105   $  3.64
mary                      118.00   35   $  2.36
root                       26.00   12   $  0.52
zhang                       9.00    1   $  0.18

total                     337.00  154   $  6.74</screen>
	      </informalexample>

	    <para>To compute the dollar amount due,
	      <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry> uses
	      the <literal>pc</literal> capability in the
	      <filename>/etc/printcap</filename> file (default of 200, or 2
	      cents per page). Specify, in hundredths of cents, the price per
	      page or per foot you want to charge for printouts in this
	      capability. You can override this value when you run
	      <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry> with
	      the <option>-p</option> option. The units for the
	      <option>-p</option> option are in dollars, though, not
	      hundredths of cents. For example,
	      
	      <informalexample>
		<screen>&prompt.root; <userinput>pac -p1.50</userinput></screen>
	      </informalexample>

	      makes each page cost one dollar and fifty
	      cents. You can really rake in the profits by using this
	      option.</para>
	    
	    <para>Finally, running <command>pac -s</command> will save the
	      summary information in a summary accounting file, which is named
	      the same as the printer's accounting file, but with
	      <literal>_sum</literal> appended to the name. It then truncates
	      the accounting file. When you run  <citerefentry>
		<refentrytitle>pac</refentrytitle></citerefentry>
	      again, it rereads the summary file to get starting totals, then
	      adds information from the regular accounting file.</para>
	    
	  </sect3>
	  
	  <sect3>
	    <title>How Can You Count Pages Printed?</title>
	    
	    <para>In order to perform even remotely accurate accounting, you
	      need to be able to determine how much paper a job uses. This is
	      the essential problem of printer accounting.</para>
	    
	    <para>For plain text jobs, the problem's not that hard to solve:
	      you count how many lines are in a job and compare it to how many
	      lines per page your printer supports. Do not forget to take
	      into account backspaces in the file which overprint lines, or
	      long logical lines that wrap onto one or more additional
	      physical lines.</para>
	    
	    <para>The text filter <command>lpf</command>
	      (introduced in <link linkend="printing-advanced-lpf">lpf:
		a Text Filter</link>) takes into account these things when it does
	      accounting. If you are writing a text filter which needs to do
	      accounting, you might want to examine <command>lpf</command>'s source code.</para>
	    
	    <para>How do you handle other file formats, though?</para>
	    
	    <para>Well, for DVI-to-LaserJet or DVI-to-PostScript conversion,
	      you can have your filter parse the diagnostic output of <citerefentry>
		<refentrytitle>dvilj</refentrytitle></citerefentry> or
	      <citerefentry>
		<refentrytitle>dvips</refentrytitle></citerefentry> and look to see how many pages were converted. You might be able to do similar things with other file formats and conversion programs.</para>
	    
	    <para>But these methods suffer from the fact that the printer may
	      not actually print all those pages. For example, it could jam,
	      run out of toner, or explode&mdash;and the user would still get
	      charged.</para>
	    
	    <para>So, what can you do?</para>
	    
	    <para>There is only one <emphasis>sure</emphasis> way to do
	      <emphasis>accurate</emphasis> accounting. Get a printer that
	      can tell you how much paper it uses, and attach it via a serial
	      line or a network connection. Nearly all PostScript printers
	      support this notion. Other makes and models do as well
	      (networked Imagen laser printers, for example). Modify the
	      filters for these printers to get the page usage after they
	      print each job and have them log accounting information based on
	      that value <emphasis>only</emphasis>. There is no line counting
	      nor error-prone file examination required.</para>
	    
	    <para>Of course, you can always be generous and make all printouts
	      free.</para>
	    
	  </sect3>
	</sect2>
      </sect1>
      
      <sect1 id="printing-lpd-alternatives">
	<title>Alternatives to the Standard Spooler</title>
	
	<para>If you have been reading straight through this manual, by now
	  you have learned just about everything there is to know about the
	  LPD spooling system that comes with FreeBSD. You can probably
	  appreciate many of its shortcomings, which naturally leads to the
	  question: &ldquo;What other spooling systems are out there (and work with
	  FreeBSD)?&rdquo;</para>
	
	<para>Unfortunately, I have located only <emphasis>two</emphasis>
	  alternatives&mdash;and they are almost identical to each other! They
	  are:</para>
	
	  <variablelist>
	    <varlistentry><term>PLP, the Portable Line Printer Spooler
		System</term>
	      <listitem>
		<para>PLP was based on software developed by Patrick Powell
		  and then maintained by an Internet-wide group of developers.
		  The main site for the software is at  <ulink
		    URL="ftp://ftp.iona.ie/pub/plp">ftp://ftp.iona.ie/pub/plp</ulink>. There is also a <ulink URL="http://www.iona.ie:8000/www/hyplan/jmason/plp.html">web page</ulink>.</para>
		
		<para>It is quite similar to the BSD LPD spooler, but boasts a
		  host of features, including:</para>
		  <itemizedlist>
		    
		    <listitem>
		      <para>Better network support, including built-in support
			for networked printers, NIS-maintained printcaps, and
			NFS-mounted spooling directories</para>
		    </listitem>
		    
		    <listitem>
		      <para>Sophisticated queue management, allowing multiple
			printers on a queue, transfer of jobs between queues,
			and queue redirection</para>
		    </listitem>
		    
		    <listitem>
		      <para>Remote printer control functions</para>
		    </listitem>
		    
		    <listitem>
		      <para>Prioritization of jobs</para>
		    </listitem>
		    
		    <listitem>
		      <para>Expansive security and access options</para>
		    </listitem>
		    
		  </itemizedlist>

	      </listitem>
	    </varlistentry>
	    
	    <varlistentry><term>LPRng</term>
	      
	      <listitem>
		<para>LPRng, which purportedly means &ldquo;LPR: the Next
		  Generation&rdquo; is a complete rewrite of PLP. Patrick Powell
		  and Justin Mason (the principal maintainer of PLP)
		  collaborated to make LPRng. The main site for LPRng is
		  <ulink
		    URL="ftp://dickory.sdsu.edu/pub/LPRng">ftp://dickory.sdsu.edu/pub/LPRng</ulink>.</para>
		
	      </listitem>
	    </varlistentry>
	  </variablelist>
	
      </sect1>
      
      <sect1>
	<title>Acknowledgments</title>
	
	<para>I would like to thank the following people who have assisted in
	  the development of this document:</para>
	
	
	  <variablelist>
	    <varlistentry><term>Daniel Eischen
		<email>deischen@iworks.interworks.org</email></term>
	      <listitem>
		<para>For providing a plethora of HP filter programs for
		  perusal.</para>
	      </listitem>
	    </varlistentry>
	    
	    <varlistentry><term>&a.jehamby;</term>
	      
	      <listitem>
		<para>For the Ghostscript-to-HP filter.</para>
	      </listitem>
	    </varlistentry>
	    
	    <varlistentry><term>My wife, Mary Kelly
		<email>urquhart@argyre.colorado.edu</email></term>
	      
	      <listitem>
		<para>For allowing me to spend more time with FreeBSD than
		  with her.</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>
	  
      </sect1>
    </chapter>

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