path: root/en_US.ISO8859-1/books/handbook/printing/chapter.sgml

<!--
     The FreeBSD Documentation Project

     $FreeBSD$
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<chapter id="printing">
  <chapterinfo>
    <authorgroup>
      <author>
	<firstname>Sean</firstname>
	<surname>Kelly</surname>
	<contrib>Contributed by </contrib>
      </author>
      <!-- 30 Sept 1995 -->
    </authorgroup>
    <authorgroup>
      <author>
	<firstname>Jim</firstname>
	<surname>Mock</surname>
	<contrib>Restructured and updated by </contrib>
	<!-- Mar 2000 -->
      </author>
    </authorgroup>
  </chapterinfo>

  <title>Printing</title>

  <sect1 id="printing-synopsis">
    <title>Synopsis</title>
    <indexterm><primary>LPD spooling system</primary></indexterm>
    <indexterm><primary>printing</primary></indexterm>

    <para>FreeBSD can be used to print to a wide variety of printers, from the
      oldest impact printer to the latest laser printers, and everything in
      between, allowing you to produce high quality printed output from the
      applications you run.</para>

    <para>FreeBSD can also be configured to act as a print server on a
      network; in this capacity FreeBSD can receive print jobs from a variety
      of other computers, including other FreeBSD computers, &windows; and &macos;
      hosts.  FreeBSD will ensure that one job at a time is printed, and can
      keep statistics on which users and machines are doing the most printing,
      produce <quote>banner</quote> pages showing who's printout is who's, and
      more.</para>

    <para>After reading this chapter, you will know:</para>

    <itemizedlist>
      <listitem>
	<para>How to configure the FreeBSD print spooler.</para>
      </listitem>

      <listitem>
	<para>How to install print filters, to handle special print jobs
	  differently, including converting incoming documents to print
	  formats that your printers understand.</para>
      </listitem>

      <listitem>
	<para>How to enable header, or banner pages on your printout.</para>
      </listitem>

      <listitem>
	<para>How to print to printers connected to other computers.</para>
      </listitem>

      <listitem>
	<para>How to print to printers connected directly to the
	  network.</para>
      </listitem>

      <listitem>
	<para>How to control printer restrictions, including limiting the size
	  of print jobs, and preventing certain users from printing.</para>
      </listitem>

      <listitem>
	<para>How to keep printer statistics, and account for printer
	  usage.</para>
      </listitem>

      <listitem>
	<para>How to troubleshoot printing problems.</para>
      </listitem>
    </itemizedlist>

    <para>Before reading this chapter, you should:</para>

    <itemizedlist>
      <listitem>
	<para>Know how to configure and install a new kernel 
	  (<xref linkend="kernelconfig">).</para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1 id="printing-intro-spooler">
    <title>Introduction</title>

    <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 <application>LPD</application> spooling system.
      It is the standard printer control system in FreeBSD.  This
      chapter introduces the <application>LPD</application> spooling
      system, often simply called <application>LPD</application>, and
      will guide you through its configuration.</para>

    <para>If you are already familiar with 
      <application>LPD</application> or another printer spooling
      system, you may wish to skip to section <link
      linkend="printing-intro-setup">Setting up the spooling
      system</link>.</para>

    <para><application>LPD</application> 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>

      <indexterm><primary>print jobs</primary></indexterm>
      <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 a 
	  <application>LPD</application> 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
      (<filename>/etc/printcap</filename>), and by providing the special
      filter programs, you can enable the <application>LPD</application>
      system to do all or some
      subset of the above for a great variety of printer hardware.</para>

    <sect2 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><application>LPD</application> prints jobs in the background;
	    you do not have to wait
	    for data to be copied to the printer.</para>
	</listitem>

	<indexterm><primary>&tex;</primary></indexterm>
	<listitem>
	  <para><application>LPD</application> 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>
    </sect2>
  </sect1>

  <sect1 id="printing-intro-setup">
    <title>Basic Setup</title>

    <para>To use printers with the <application>LPD</application> spooling
      system, you will need to
      set up both your printer hardware and the 
      <application>LPD</application> 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 
	  <application>LPD</application> 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>

    <sect2 id="printing-simple">
      <title>Simple Printer Setup</title>

      <para>This section tells how to configure printer hardware and the
	<application>LPD</application> 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 set up the 
	    <application>LPD</application> 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 Interfaces</link>.</para>

      <para>Although this section is called <quote>Simple Printer
	Setup</quote>, it is actually fairly complex.  Getting the printer
	to work with your computer and the <application>LPD</application>
	spooler is the hardest
	part.  The advanced options like header pages and accounting are
	fairly easy once you get the printer working.</para>

      <sect3 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>

	<sect4 id="printing-ports">
	  <title>Ports and Cables</title>

	  <para>Printers sold for use on PC's today generally come
	    with one or more of the following three interfaces:</para>

	  <itemizedlist>
	    <indexterm>
        <primary>printers</primary>
        <secondary>serial</secondary>
      </indexterm>
	    <listitem>
	      <para><emphasis>Serial</emphasis> interfaces, also known
		as RS232C or RS232D, or COM ports, 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.  Most PC serial ports have a maximum
	        transmission rate of 115200&nbsp;bps, which makes printing
	        large graphic print jobs with them impractical.</para>
	    </listitem>

	    <indexterm>
        <primary>printers</primary>
        <secondary>parallel</secondary>
      </indexterm>
	    <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
		and are faster than RS232 serial.
		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>

	      <indexterm>
	        <primary>centronics</primary>
		<see>parallel printers</see>
	      </indexterm>
	      <para>Parallel interfaces are sometimes known as
		<quote>Centronics</quote> interfaces, named after the
		connector type on the printer.</para>
	    </listitem>

	    <indexterm>
        <primary>printers</primary>
        <secondary>USB</secondary>
	</indexterm>
	    <listitem>
	      <para>USB interfaces, named for the Universal Serial
	        Bus, can run at even faster speeds than parallel or
	        RS232 serial interfaces.  Cables are simple and cheap.
	        USB is superior to RS232 Serial and to Parallel for
	        printing, but it is not as well supported under &unix;
	        systems.  A way to avoid this problem is to purchase a
	        printer that has both a USB interface and a Parallel
	        interface, as many printers do.</para>
	    </listitem>
	  </itemizedlist>

	  <para>In general, Parallel interfaces usually offer just
	    one-way communication (computer to printer) while serial
	    and USB gives you two-way. Newer parallel ports (EPP and
	    ECP) and printers
	    can communicate in both directions under FreeBSD when a
	    IEEE1284 compliant cable is used.</para>

	  <indexterm><primary>PostScript</primary></indexterm>

	  <para>Two-way communication to the printer over a parallel
	    port is generally done in one of two ways.  The first method
	    uses a custom built printer driver for FreeBSD that speaks
	    the proprietary language used by the printer.  This is
	    common with inkjet printers and can be used for reporting
	    ink levels and other status information.  The second
	    method is used when the printer supports
	    &postscript;.</para>

	  <para>&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>
	</sect4>
	  
	<sect4 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/ppc0</filename> to
	    FreeBSD; the second is <filename>/dev/ppc1</filename>, and so
	    on.  The printer device name uses the same scheme:
	    <filename>/dev/lpt0</filename> for the printer on the first
	    parallel ports etc.</para>
	</sect4>

	<sect4 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 <quote>proper serial
	    cable</quote> 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
		<quote>DTE-to-DCE</quote> cable.</para>
	    </listitem>

	    <indexterm><primary>null-modem cable</primary></indexterm>
	    <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
		<quote>DTE-to-DTE</quote> 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>

	  <indexterm><primary>baud rate</primary></indexterm>
	  <indexterm><primary>parity</primary></indexterm>
	  <indexterm><primary>flow control protocol</primary></indexterm>
	  <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
	    <literal>bps</literal> (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
	    <quote>in-band</quote> or <quote>software</quote>) flow control.
	    Remember these settings for the software configuration that
	    follows.</para>
	</sect4>
      </sect3>

      <sect3 id="printing-software">
	<title>Software Setup</title>

	<para>This section describes the software setup necessary to print
	  with the <application>LPD</application> 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 <application>LPD</application> for the printer by 
	      modifying the file
	      <filename>/etc/printcap</filename>.  You will find out how
	      to do this later in this chapter.</para>
	  </step>
	</procedure>

	<sect4 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>

	  <screen>&prompt.root; <userinput>grep sio<replaceable>N</replaceable> /var/run/dmesg.boot</userinput></screen>

	  <para>Where <replaceable>N</replaceable> is the number of the
	    serial port, starting from zero.  If you see output similar to
	    the following:</para>

	  <screen>sio2 at port 0x3e8-0x3ef irq 5 on isa
sio2: type 16550A</screen>

	  <para>then the kernel supports the port.</para>

	  <para>To find out if the kernel supports a parallel interface,
	    type:</para>

	  <screen>&prompt.root; <userinput>grep ppc<replaceable>N</replaceable> /var/run/dmesg.boot</userinput></screen>

	  <para>Where <replaceable>N</replaceable> is the number of the
	    parallel port, starting from zero.  If you see output similar
	    to the following:</para>
	    
	    <screen>ppc0: &lt;Parallel port&gt; at port 0x378-0x37f irq 7 on isa0
ppc0: SMC-like chipset (ECP/EPP/PS2/NIBBLE) in COMPATIBLE mode
ppc0: FIFO with 16/16/8 bytes threshold</screen>
	    
	    <para>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>
      </sect3>

      <sect3 id="printing-dev-ports">
	<title>Adding <filename>/dev</filename> Entries for the
	  Ports</title>

	<note><para>FreeBSD&nbsp;5.0 includes the <literal>devfs</literal>
	  filesystem which automatically creates device nodes as
	  needed.  If you are running a version of FreeBSD with
	  <literal>devfs</literal> enabled then you can safely skip
	  this section.</para></note>

	<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 <username>root</username> with the &man.su.1; command.
	       Enter the <username>root</username> password when prompted.</para>
	  </step>

	  <step>
	    <para>Change to the <filename>/dev</filename>
	      directory:</para>

	    <screen>&prompt.root; <userinput>cd /dev</userinput></screen>
	  </step>

	  <step>
	    <para>Type:</para>

	    <screen>&prompt.root; <userinput>./MAKEDEV <replaceable>port</replaceable></userinput></screen>

	    <para>Where <replaceable>port</replaceable> is the device
	      entry for the port you want to make.  Use
	      <literal>lpt0</literal> for the printer on the first parallel port,
	      <literal>lpt1</literal> for the printer on the second port, 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>

	    <screen>&prompt.root; <userinput>ls -l <replaceable>port</replaceable></userinput></screen>

	    <para>to make sure the device entry got created.</para>
	  </step>
	</procedure>

	<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.  The generic printer
	    device driver (&man.lpt.4;) on FreeBSD&nbsp;4.X and 5.X
	    uses the &man.ppbus.4; system, which controls the port
	    chipset with the &man.ppc.4; driver.</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 usually somewhat faster
	    but uses up a precious IRQ line.  Some newer HP printers
	    are claimed not to work correctly in interrupt mode,
	    apparently due to some (not yet exactly understood) timing
	    problem.  These printers need polled mode.  You should use
	    whichever one works.  Some printers will work in both
	    modes, but are painfully slow in interrupt mode.</para>

	  <para>You can set the communications mode in two ways: by
	    configuring the kernel or by using the &man.lptcontrol.8;
	    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
		an <literal>ppc0</literal> entry.  If you are setting up
		the second parallel port, use <literal>ppc1</literal>
		instead.  Use <literal>ppc2</literal> for the third port,
		and so on.</para>

	      <itemizedlist>
		<listitem>
		  <para>If you want interrupt-driven mode, for FreeBSD&nbsp;4.X add the
		    <literal>irq</literal> specifier:</para>

		  <programlisting>device ppc0 at isa? irq <replaceable>N</replaceable></programlisting>

		  <para>Where <replaceable>N</replaceable> is the IRQ
		    number for your computer's parallel port.</para>

		  <para>For FreeBSD&nbsp;5.X, edit the following line:</para>

		  <programlisting>hint.ppc.0.irq="<replaceable>N</replaceable>"</programlisting>

		  <para>in the <filename>/boot/device.hints</filename> file
		    and replace <replaceable>N</replaceable> with the right
		    IRQ number.  The kernel configuration file must
		    also contain the &man.ppc.4; driver:</para>

		  <screen>device ppc</screen>

		</listitem>

		<listitem>
		  <para>If you want polled mode, do not add the
		    <literal>irq</literal> specifier:</para>

		  <para>For FreeBSD&nbsp;4.X, use the following line in
		    your kernel configuration file:</para>

		  <programlisting>device ppc0 at isa?</programlisting>

		  <para>For FreeBSD&nbsp;5.X, simply remove in your
		    <filename>/boot/device.hints</filename> file, the
		    following line:</para>

		  <programlisting>hint.ppc.0.irq="<replaceable>N</replaceable>"</programlisting>

		  <para>In some cases, this is not enough to put the
		    port in polled mode under FreeBSD&nbsp;5.X.  Most of
		    time it comes from &man.acpi.4; driver, this latter
		    is able to probe and attach devices, and therefore,
		    control the access mode to the printer port.  You
		    should check your &man.acpi.4; configuration to
		    correct this problem.</para>
		</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>
	    &man.lptcontrol.8;:</para>

	  <procedure>
	    <step>
	      <para>Type:</para>

	      <screen>&prompt.root; <userinput>lptcontrol -i -d /dev/lpt<replaceable>N</replaceable></userinput></screen>

	      <para>to set interrupt-driven mode for
		<literal>lpt<replaceable>N</replaceable></literal>.</para>
	    </step>

	    <step>
	      <para>Type:</para>

	      <screen>&prompt.root; <userinput>lptcontrol -p -d /dev/lpt<replaceable>N</replaceable></userinput></screen>

	      <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 &man.lptcontrol.8; 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  &man.lptest.1; is perfect: it generates all 96
	    printable ASCII characters in 96 lines.</para>

	  <indexterm><primary>PostScript</primary></indexterm>
	  <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>

	  <para>The above &postscript; code can be placed into a file and
	    used as shown in the examples appearing in the following
	    sections.</para>

	  <indexterm><primary>PCL</primary></indexterm>
	  <note>
	    <para>When this document refers to a printer language, it is
	      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>

	    <indexterm>
        <primary>printers</primary>
        <secondary>parallel</secondary>
      </indexterm>
	    <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 <username>root</username> with  &man.su.1;.</para>
	      </step>

	      <step>
		<para>Send data to the printer.</para>

		<itemizedlist>
		  <listitem>
		    <para>If the printer can print plain text, then use
		      &man.lptest.1;.  Type:</para>

		    <screen>&prompt.root; <userinput>lptest &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>

		    <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>

		    <screen>&prompt.root; <userinput>cat &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>

		    <para>Then, line by line, type the program
		      <emphasis>carefully</emphasis> as you cannot edit a
		      line once you have pressed <literal>RETURN</literal>
		      or <literal>ENTER</literal>.  When you have finished
		      entering the program, press
		      <literal>CONTROL+D</literal>, or whatever your end
		      of file key is.</para>

		    <para>Alternatively, you can put the program in a file
		      and type:</para>

		    <screen>&prompt.root; <userinput>cat <replaceable>file</replaceable> &gt; /dev/lpt<replaceable>N</replaceable></userinput></screen>

		    <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>

	    <indexterm>
        <primary>printers</primary>
        <secondary>serial</secondary>
      </indexterm>
	    <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 <username>root</username> with &man.su.1;.</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>

		<indexterm><primary>bits-per-second</primary></indexterm>
		<indexterm><primary>serial port</primary></indexterm>
		<indexterm><primary>parity</primary></indexterm>
		<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&nbsp;bps with
		  no parity:</para>

		<programlisting>printer:dv=/dev/ttyd2:br#19200:pa=none</programlisting>
	      </step>

	      <step>
		<para>Connect to the printer with &man.tip.1;.
		  Type:</para>

		<screen>&prompt.root; <userinput>tip printer</userinput></screen>

		<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
		      &man.lptest.1;.  Type:</para>

		    <screen>&prompt.user; <userinput>$lptest</userinput></screen>
		  </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 <literal>CONTROL+D</literal>.</para>

		    <para>Alternatively, you can put the program in a file
		      and type:</para>

		    <screen>&prompt.user; <userinput>&gt;<replaceable>file</replaceable></userinput></screen>

		    <para>Where <replaceable>file</replaceable> is the
		      name of the file containing the program.  After
		      &man.tip.1; 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 <application>LPD</application> to control access
	  to your printer.</para>

	<para>You configure <application>LPD</application> by editing the file
	  <filename>/etc/printcap</filename>.  The 
	  <application>LPD</application> spooling system
	  reads this file each time the spooler is used, so updates to the
	  file take immediate effect.</para>

	<indexterm>
    <primary>printers</primary>
    <secondary>capabilities</secondary>
  </indexterm>
	<para>The format of the &man.printcap.5; 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 &man.cgetent.3;.</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 the 
	      <link linkend="printing-naming">Naming the Printer</link>
	      section for more information on naming.</para>
	  </step>

	  <indexterm><primary>header pages</primary></indexterm>
	  <step>
	    <para>Turn off header pages (which are on by default) by
	      inserting the <literal>sh</literal> capability; see the
	      <link linkend="printing-no-header-pages">Suppressing Header
	      Pages</link> section for more information.</para>
	  </step>

	  <step>
	    <para>Make a spooling directory, and specify its location with
	      the <literal>sd</literal> capability; see the <link
	      linkend="printing-spooldir">Making the Spooling
	      Directory</link> section for more information.</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 the <link
	      linkend="printing-device">Identifying the Printer
	      Device</link> for more information.  Also, if the printer is
	      on a serial port, set up the communication parameters with
	      the <literal>ms#</literal> capability which is discussed in the <link
	      linkend="printing-commparam">Configuring Spooler
	      Communications Parameters</link> section.</para>
	  </step>

	  <step>
	    <para>Install a plain text input filter; see the <link
	    linkend="printing-textfilter">Installing the Text
	    Filter</link> section for details.</para>
	  </step>

	  <step>
	    <para>Test the setup by printing something with the
	      &man.lpr.1; command.  More details are available in the
	      <link linkend="printing-trying">Trying It Out</link> and
	      <link
	      linkend="printing-troubleshooting">Troubleshooting</link>
	      sections.</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 <application>LPD</application> 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.  The section entitled <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 of 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 <application>LPD</application> 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>
	  <indexterm>
      <primary>printing</primary>
      <secondary>header pages</secondary>
    </indexterm>

	  <para>The <application>LPD</application> 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 an 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>
	  <indexterm><primary>printer spool</primary></indexterm>
	  <indexterm><primary>print jobs</primary></indexterm>

	  <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 &man.mkdir.1;.</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>

	  <screen>&prompt.root; <userinput>mkdir /var/spool/<replaceable>printer-name</replaceable></userinput></screen>

	  <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 
	    <application>LPD</application>.  We
	    will do this for our two example printers
	    <literal>rattan</literal> and
	    <literal>bamboo</literal>:</para>

	  <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>

	  <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>

	    <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>
	  </note>

	  <para>Finally, you need to tell <application>LPD</application>
	    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 the <link linkend="printing-dev-ports">Adding
	    <filename>/dev</filename> Entries for the Ports</link>
	    section, we identified which entry in the
	    <filename>/dev</filename> directory FreeBSD will use to
	    communicate with the printer.  Now, we tell 
	    <application>LPD</application> 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
	    <literal>rattan</literal> is on the first parallel port, and
	    <literal>bamboo</literal> 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,
	    <application>LPD</application> 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 entitled, <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>
	  <indexterm>
      <primary>printers</primary>
      <secondary>serial</secondary>
    </indexterm>

	  <para>For printers on serial ports, <application>LPD</application>
	    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, 38400, 57600, or 115200 bits-per-second.</para>
	      </listitem>
	    </varlistentry>

	    <varlistentry>
	      <term><literal>ms#<replaceable>stty-mode</replaceable></literal></term>

	      <listitem>
		<para>Sets the options for the terminal device after
		  opening the device.  &man.stty.1; explains the
		  available options.</para>
	      </listitem>
	    </varlistentry>
	  </variablelist>

	  <para>When <application>LPD</application> opens the device
	    specified by the <literal>lp</literal> capability, it sets
	    the characteristics of the device to those specified with
	    the <literal>ms#</literal> capability.  Of particular
	    interest will be the <literal>parenb</literal>,
	    <literal>parodd</literal>, <literal>cs5</literal>,
	    <literal>cs6</literal>, <literal>cs7</literal>,
	    <literal>cs8</literal>, <literal>cstopb</literal>,
	    <literal>crtscts</literal>, and <literal>ixon</literal>
	    modes, which are explained in the &man.stty.1;
	    manual page.</para>

	  <para>Let us add to our example printer on the sixth serial
	    port.  We will set the bps rate to 38400.  For the mode,
	    we will set no parity with <literal>-parenb</literal>,
	    8-bit characters with <literal>cs8</literal>,
	    no modem control with <literal>clocal</literal> and
	    hardware flow control with <literal>crtscts</literal>:</para>

	  <programlisting>bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
        :sh:sd=/var/spool/lpd/bamboo:\
        :lp=/dev/ttyd5:ms#-parenb cs8 clocal crtscts:</programlisting>
	</sect4>

	<sect4 id="printing-textfilter">
	  <title>Installing the Text Filter</title>
	  <indexterm>
	    <primary>printing</primary>
	    <secondary>filters</secondary>
	  </indexterm>

	  <para>We are now ready to tell <application>LPD</application>
	    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 <application>LPD</application> runs when it 
	    has a job to print.  When <application>LPD</application>
	    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
	    the <link linkend="printing-advanced-filters">Filters</link>
	    section.</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 entitled <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>

	  <screen>&prompt.root; <userinput>chmod 555 /usr/local/libexec/if-simple</userinput></screen>

	  <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:ms#-parenb cs8 clocal crtscts:\
        :if=/usr/local/libexec/if-simple:</programlisting>

	  <note>
	    <para>A copy of the <filename>if-simple</filename> script
	      can be found in the <filename
	      role="directory">/usr/share/examples/printing</filename>
	      directory.</para>
	  </note>
	</sect4>

	<sect4>
	  <title>Turn on <application>LPD</application></title>

	  <para>&man.lpd.8; is run from <filename>/etc/rc</filename>,
	    controlled by the <literal>lpd_enable</literal> variable.  This
	    variable defaults to <literal>NO</literal>.  If you have not done
	    so already, add the line:</para>

	  <programlisting>lpd_enable="YES"</programlisting>

	  <para>to <filename>/etc/rc.conf</filename>, and then either restart
	    your machine, or just run &man.lpd.8;.</para>

	  <screen>&prompt.root; <userinput>lpd</userinput></screen>
	</sect4>
	
	<sect4 id="printing-trying">
	  <title>Trying It Out</title>

	  <para>You have reached the end of the simple 
	    <application>LPD</application> 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 <application>LPD</application> system, you 
	    use the command &man.lpr.1;,
	    which submits a job for printing.</para>

	  <para>You can combine &man.lpr.1; with the &man.lptest.1;
	    program, introduced in section <link
	    linkend="printing-testing">Checking Printer
	    Communications</link> to generate some test text.</para>

	  <para><emphasis>To test the simple <application>LPD</application>
	      setup:</emphasis></para>

	  <para>Type:</para>

	  <screen>&prompt.root; <userinput>lptest 20 5 | lpr -P<replaceable>printer-name</replaceable></userinput></screen>
	  
	  <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 &man.lpr.1; 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 &man.lptest.1;.  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 &man.lptest.1;, 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
	    &man.lptest.1; 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 <link
	    linkend="printing-troubleshooting">Troubleshooting</link>
	    section.</para>
	</sect4>
      </sect3>
    </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>
      <indexterm>
	<primary>printing</primary>
	<secondary>filters</secondary>
      </indexterm>
      
      <para>Although <application>LPD</application> 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 <quote>under the hood</quote>
            when <application>LPD</application> 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><application>LPD</application> 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.  You should read 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.  You should read
            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 
	    <application>LPD</application>:
            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>
      
      <note>
	<para>A copy of the various scripts described below can be
	  found in the <filename
	  role="directory">/usr/share/examples/printing</filename>
	  directory.</para>
      </note>

      <sect3 id="printing-advanced-filters">
        <title>How Filters Work</title>

        <para>As mentioned before, a filter is an executable program started
          by <application>LPD</application> to handle the device-dependent part of
	  communicating with the printer.</para>
            
        <para>When <application>LPD</application> 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>
            
        <indexterm>
          <primary><command>troff</command></primary>
        </indexterm>
        <para>Which filter <application>LPD</application> 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      
            &man.lpr.1; command line.  For example, if the user typed
          <command>lpr -t</command>, <application>LPD</application> 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 
	      <application>LPD</application> documentation, handles
              regular text printing.  Think of it as the default filter.  
	      <application>LPD</application>
              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 is 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>

	  <indexterm>
      <primary>printing</primary>
      <secondary>filters</secondary>
    </indexterm>          
          <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 
		<application>LPD</application> to
                try to print the file again.  <application>LPD</application>
		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
                <application>LPD</application> to try again.  
		<application>LPD</application> 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>
        <indexterm><primary>print jobs</primary></indexterm>

        <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>

        <indexterm>
          <primary>printers</primary>
          <secondary>serial</secondary>
        </indexterm>
        <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 <application>LPD</application> 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
#

IFS="" read -r 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
          <literal>a2ps</literal> that you might want to investigate.</para>
      </sect3>
          
      <sect3 id="printing-advanced-ps">
        <title>Simulating &postscript; on Non &postscript; Printers</title>
        <indexterm>
          <primary>PostScript</primary>
          <secondary>emulating</secondary>
        </indexterm>
        <indexterm>
          <primary>Ghostscript</primary></indexterm>
        <para>&postscript; is the <emphasis>de facto</emphasis> standard for
          high quality typesetting and printing.  &postscript; is, however, an
          <emphasis>expensive</emphasis> standard. Thankfully, Aladdin
          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 is 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
          <command>gs</command> (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/ifhp

#
#  Treat LF as CR+LF (to avoid the "staircase effect" on HP/PCL
#  printers):
#
printf "\033&amp;k2G" || exit 2

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

if [ "$first_two_chars" = "%!" ]; then
    #
    #  It is PostScript; use Ghostscript to scan-convert and print it.
    #
    /usr/local/bin/gs -dSAFER -dNOPAUSE -q -sDEVICE=djet500 \
      -sOutputFile=- - &amp;&amp; exit 0
else
    #
    #  Plain text or HP/PCL, so just print it directly; print a form feed
    #  at the end to eject the last page.
    #
    echo "$first_line" &amp;&amp; cat &amp;&amp; printf "\033&amp;l0H" &amp;&amp; 
exit 0
fi

exit 2</programlisting>

        <para>Finally, you need to notify <application>LPD</application> of 
	  the filter via the <literal>if</literal> capability:</para>
            
        <programlisting>:if=/usr/local/libexec/ifhp:</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>
          <indexterm>
            <primary>&tex;</primary>
            <secondary>printing dvi files</secondary>
          </indexterm>
          
          <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>
                
          <screen>&prompt.user; <userinput>dvips seaweed-analysis.dvi</userinput>
&prompt.user; <userinput>lpr seaweed-analysis.ps</userinput></screen>
                
          <para>By installing a conversion filter for DVI files, we can skip
            the hand conversion step each time by having 
	    <application>LPD</application> do it for us.
            Now, each time we get a DVI file, we are just one step away from
            printing it:</para>
              
          <screen>&prompt.user; <userinput>lpr -d seaweed-analysis.dvi</userinput></screen>
                
          <para>We got <application>LPD</application> 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 
	    <application>LPD</application> 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>tf</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>
              
          <indexterm><primary>FORTRAN</primary></indexterm>
          <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 <quote>print Printerleaf
            files.</quote></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 
	    <application>LPD</application> 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:ms#-parenb cs8 clocal crtscts: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 <command>dvips</command> 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 
	    <application>LPD</application>
            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 "\033&amp;l0H" &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: <command>dvi2xx</command> is the name of the package.
            Installing this package gives us the program we need,
            <command>dvilj2p</command>, which converts DVI into LaserJet IIp,
            LaserJet III, and LaserJet 2000 compatible codes.</para>
              
          <para><command>dvilj2p</command> makes the filter
            <command>hpdf</command> quite complex since
            <command>dvilj2p</command> 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
            <command>dvilj2p</command> 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 &man.lpr.1; 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>
              
          <indexterm><primary>apsfilter</primary></indexterm>
          <indexterm>
            <primary>printing</primary>
            <secondary>filters</secondary>
            <tertiary>apsfilter</tertiary>
          </indexterm>
          <para>The FreeBSD Ports Collection has a text filter that performs
            automatic conversion called <command>apsfilter</command>.  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 <application>LPD</application> 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><application>LPD</application> starts an output filter once
	      for the entire job instead
              of once for each file in the job.</para>
          </listitem>
          
          <listitem>
            <para><application>LPD</application> 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><application>LPD</application> 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 <application>LPD</application>.</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 
	  <application>LPD</application> does not give any
          user or host information to the output filter.)</para>
            
        <para>On a single printer, <application>LPD</application>
	  allows both an output filter and text or other filters.  In
	  such cases, <application>LPD</application> will start the
	  output filter
          to print the header page (see section <link
            linkend="printing-advanced-header-pages">Header Pages</link>)
          only.  <application>LPD</application> 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 <literal>SIGSTOP</literal>
	  to itself.  When 
	  <application>LPD</application>'s
          done running other filters, it will restart the output filter by
          sending <literal>SIGCONT</literal> to it.</para>
            
        <para>If there is an output filter but <emphasis>no</emphasis> text
          filter and <application>LPD</application> is working on a plain
	  text job, <application>LPD</application> 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>
            
        <indexterm><primary>page accounting</primary></indexterm>
        <indexterm>
          <primary>accounting</primary>
          <secondary>printer</secondary>
        </indexterm>
        <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>
          
      <indexterm>
        <primary>banner pages</primary>
	<see>header pages</see>
      </indexterm>
      <indexterm><primary>header pages</primary></indexterm>
      <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 <application>LPD</application> 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> section, we turned off header pages by specifying
          <literal>sh</literal> (meaning <quote>suppress header</quote>) 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 the <link
            linkend="printing-advanced-of">Output Filters</link> section 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 the <link
            linkend="printing-lpr-options-misc">Header Page Options</link> section for
          more &man.lpr.1; options.</para>

        <note>
          <para><application>LPD</application> 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, <application>LPD</application> 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 <hostid>rose</hostid>):</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><application>LPD</application> 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, <application>LPD</application> 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, <application>LPD</application> 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 <application>LPD</application>'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
          <quote>add one page</quote> 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 <application>LPD</application>
	  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 <application>LPD</application>'s paradigm and make
	      header pages free.</para>
          </listitem>
          
          <listitem>
            <para>Install an alternative to <application>LPD</application>,
	      such as 
		<application>LPRng</application>. Section
              <link linkend="printing-lpd-alternatives">Alternatives to the
                Standard Spooler</link> tells more about other spooling
              software you can substitute for <application>LPD</application>.
	    </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 <application>LPD</application> will start
	      the output filter only for
              the header pages.  And the output filter can parse the header
              page text that <application>LPD</application> 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, <application>LPD</application> 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 
	  <application>LPD</application> 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 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 <quote>suppress header page</quote> 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 
	  <application>LPD</application> will
          not generate a header page, and neither will your output filter.
          Otherwise, your output filter will read the text from 
	  <application>LPD</application> 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>
      
      <indexterm>
        <primary>printers</primary>
        <secondary>network</secondary>
      </indexterm>
      <indexterm><primary>network printing</primary></indexterm>
      <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 <application>LPD</application> 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 <application>LPD</application>
		protocol and can even queue
                jobs from remote hosts.  In this case, it acts just like a
                regular host running <application>LPD</application>.  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 <quote>attach</quote> 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 <application>LPD</application> spooling system has built-in
	  support for sending jobs to
          other hosts also running <application>LPD</application> (or are 
	  compatible with <application>LPD</application>).  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 
	  <application>LPD</application> 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 the <link linkend="printing-simple">Simple
            Printer Setup</link> section.  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 <application>LPD</application> you have enabled.  
	  Also ensure that the
          <emphasis>local host</emphasis> has authorization to use the 
	  <application>LPD</application>
          service in the <emphasis>remote host</emphasis> (see <link
            linkend="printing-advanced-restricting-remote">Restricting Jobs
            from Remote Printers</link>).</para>
            
        <indexterm>
          <primary>printers</primary>
          <secondary>network</secondary>
        </indexterm>
        <indexterm><primary>network printing</primary></indexterm>
        <para>If you are using a printer with a network interface that is
          compatible with <application>LPD</application>, 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>

        <tip>
          <para>If you are using a Hewlett Packard Laserjet then the printer
            name <literal>text</literal> will automatically perform the LF to
            CRLF conversion for you, so you will not require the
            <filename>hpif</filename> script.</para>
        </tip>
            
        <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.  <application>LPD</application>
	      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 <hostid>orchid</hostid> 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 <hostid>rose</hostid>:</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>
              
        <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>
              
        <para>Now, users on <hostid>orchid</hostid> can print to
          <literal>rattan</literal> and <literal>bamboo</literal>.  If, for
          example, a user on <hostid>orchid</hostid> typed
              
          <screen>&prompt.user; <userinput>lpr -P bamboo -d sushi-review.dvi</userinput></screen>

          the <application>LPD</application> system on <hostid>orchid</hostid>
	  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 <hostid>rose</hostid> has room in its
          <literal>bamboo</literal> spooling directory, the two 
	  <application>LPDs</application> would transfer the
          file to <hostid>rose</hostid>.  The file would wait in <hostid>rose</hostid>'s
          queue until it was finally printed.  It would be converted from DVI to
          &postscript; (since <literal>bamboo</literal> is a &postscript; printer) on
          <hostid>rose</hostid>.</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>
      
      <indexterm>
        <primary>printers</primary>
        <secondary>restricting access to</secondary>
      </indexterm>
      <para>This section gives information on restricting printer usage. The
        <application>LPD</application> 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 <application>LPD</application> 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
            &man.lpr.1; 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>
              
        <screen>lpr: multiple copies are not allowed</screen>


        <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> is 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:ms#-parenb cs8 clocal crtscts: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 &man.lpr.1;
          multiple times, or from submitting the same file multiple times in
          one job like this:</para>
              
        <screen>&prompt.user; <userinput>lpr forsale.sign forsale.sign forsale.sign forsale.sign forsale.sign</userinput></screen>
              
        <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 <username>root</username>)
	  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:ms#-parenb cs8 clocal crtscts: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>

        <indexterm><primary>print jobs</primary></indexterm>
        <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>
            
        <indexterm>
          <primary>print jobs</primary>
          <secondary>controlling</secondary>
        </indexterm>
        <para><application>LPD</application> 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
          <literal>BUFSIZ</literal> blocks, which are 1024 bytes.  If you put
	  a zero for this
          capability, there will be no limit on file size; however, if no
          <literal>mx</literal> capability is specified, then a default limit
          of 1000 blocks will be used.</para>

        <note>
          <para>The limit applies to <emphasis>files</emphasis> in a job, and
            <emphasis>not</emphasis> the total job size.</para>
        </note>

        <para><application>LPD</application> 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:mx#0: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:ms#-parenb cs8 clocal crtscts: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 <application>LPD</application> 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 
		<application>LPD</application> accepts requests with the files
                <filename>/etc/hosts.equiv</filename> and
                <filename>/etc/hosts.lpd</filename>.
		<application>LPD</application> checks to see if an
                incoming request is from a host listed in either one of these
                files.  If not, <application>LPD</application> 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
                  &man.ruserok.3; protocol, and affects programs like
                  &man.rsh.1; and &man.rcp.1;, 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
                <application>LPD</application>, the job will be refused.</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 <literal>bamboo</literal>.  We examine
                <filename>/etc/printcap</filename> to find the spooling
                directory for this printer; here is <literal>bamboo</literal>'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:ms#-parenb cs8 clocal crtscts:rw:mx#5000:\
        :if=/usr/local/libexec/psif:\
        :df=/usr/local/libexec/psdf:</programlisting>

              <para>The spooling directory is 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
                <application>LPD</application> to accept remote jobs:</para>
                  
              <screen>&prompt.root; <userinput>echo 6144 &gt; /var/spool/lpd/bamboo/minfree
              </userinput></screen>
            </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, <application>LPD</application> 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, <application>LPD</application> 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 computer resources, you can give them
                <quote>token</quote> 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>
          
      <indexterm>
        <primary>accounting</primary>
        <secondary>printer</secondary>
      </indexterm>
      <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 <application>LPD</application> 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
            <quote>print quotas.</quote> But this method requires some database
            code to track users and their quotas.</para>
        </listitem>
      </itemizedlist>
      
      <para>The <application>LPD</application> 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
            &man.pac.8;, 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>), 
	  <application>LPD</application> 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><application>LPD</application> 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.  An 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
            &man.pac.8; program.  Just change to the spooling directory for
          the printer you want to collect on and type <literal>pac</literal>.
          You will get a dollar-centric summary like the following:</para>
            
        <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>
              
        <para>These are the arguments &man.pac.8; 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 &man.pac.8; 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>
              
        <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>
              

        <para>To compute the dollar amount due,
            &man.pac.8; 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 &man.pac.8; with the
          <option>-p</option> option.  The units for the <option>-p</option>
          option are in dollars, though, not hundredths of cents.  For
          example,
              
          <screen>&prompt.root; <userinput>pac -p1.50</userinput></screen>
              
          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 &man.pac.8; 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 is 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
          <command>dvilj</command> or <command>dvips</command> 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-using">
    <title>Using Printers</title>
    
    <indexterm>
      <primary>printers</primary>
      <secondary>usage</secondary>
   </indexterm>
    <para>This section tells you how to use printers you have set up with
      FreeBSD.  Here is an overview of the user-level commands:</para>

    <variablelist>
      <varlistentry>
	<term>&man.lpr.1;</term>

	<listitem>
	  <para>Print jobs</para>
	</listitem>
      </varlistentry>
      
      <varlistentry>
	<term>&man.lpq.1;</term>

	<listitem>
	  <para>Check printer queues</para>
	</listitem>
      </varlistentry>
      
      <varlistentry>
	<term>&man.lprm.1;</term>

	<listitem>
	  <para>Remove jobs from a printer's queue</para>
	</listitem>
      </varlistentry>
    </variablelist>
    
    <para>There is also an administrative command, &man.lpc.8;, described in
      the section <link linkend="printing-lpc">Administering the 
	<application>LPD</application>
	Spooler</link>, used to control printers and their queues.</para>

    <para>All three of the commands &man.lpr.1;, &man.lprm.1;, and &man.lpq.1;
      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>
      
      <screen>&prompt.user; <userinput>lpr <replaceable>filename</replaceable> <replaceable>...</replaceable></userinput></screen>
	    
      <indexterm><primary>printing</primary></indexterm>
      <para>This prints each of the listed files to the default printer.  If
	you list no files, &man.lpr.1; reads data to
	print from standard input.  For example, this command prints some
	important system files:</para>

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

      <para>This example prints a long listing of the current directory to the
	printer named <literal>rattan</literal>:</para>
	    
      <screen>&prompt.user; <userinput>ls -l | lpr -P rattan</userinput></screen>
	    
      <para>Because no files were listed for the
	  &man.lpr.1; 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 &man.lpr.1; 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>
      
      <indexterm><primary>print jobs</primary></indexterm>
      <para>When you print with &man.lpr.1;, the data you wish to print is put
	together in a package called a <quote>print job</quote>, which is sent
	to the <application>LPD</application> 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 &man.lpq.1;.
	For a specific printer, use the <option>-P</option> option.  For
	example, the command

	<screen>&prompt.user; <userinput>lpq -P bamboo</userinput></screen>

	shows the queue for the printer named <literal>bamboo</literal>.  Here
	is an example of the output of the <command>lpq</command>
	command:</para>
	    
      <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>
	    
      <para>This shows three jobs in the queue for <literal>bamboo</literal>.
	The first job, submitted by user kelly, got assigned <quote>job
	number</quote> 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
	  &man.lpr.1; command line are treated as part of a single job.  It
	is the currently active job (note the word <literal>active</literal>
	under the <quote>Rank</quote> column), which means the printer should
	be currently printing that job.  The second job consists of data
	passed as the standard input to the &man.lpr.1; command.  The third
	  job came from user <username>mary</username>; it is a much larger
	  job. The pathname of the file she is trying to print is too long to
	  fit, so the &man.lpq.1; command just shows three dots.</para>

      <para>The very first line of the output from &man.lpq.1; is also useful:
	it tells what the printer is currently doing (or at least what 
	<application>LPD</application> thinks the printer is doing).</para>

      <para>The &man.lpq.1; command also support a <option>-l</option> option
	to generate a detailed long listing.  Here is an example of
	<command>lpq -l</command>:</para>
	    
      <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>
    </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 &man.lprm.1; command.  Often, you can
	even use &man.lprm.1; 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
	  &man.lpq.1; to find the job number.  Then type:</para>
	  
      <screen>&prompt.user; <userinput>lprm <replaceable>job-number</replaceable></userinput></screen>
	    
      <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 <literal>bamboo</literal>:</para>
	    
      <screen>&prompt.user; <userinput>lprm -P bamboo 10</userinput></screen>
      
      <para>The &man.lprm.1; 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,
		    &man.lprm.1; 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>
	  
      <screen>&prompt.user; <userinput>lprm -P rattan -</userinput></screen>
	  
      <note>
	<para>If you are working in a networked environment, &man.lprm.1; 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>
	      
	<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>
      </note>
    </sect2>
    
    <sect2 id="printing-lpr-options">
      <title>Beyond Plain Text: Printing Options</title>
      
      <para>The &man.lpr.1; 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 &man.lpr.1; 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
	    &man.pr.1; utility.</para>
	    
        <indexterm><primary>&tex;</primary></indexterm>
	<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>
	      
	<screen>&prompt.user; <userinput>lpr -P bamboo -d fish-report.dvi</userinput></screen>
	      
	<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 &man.pr.1; before printing.  See
		  &man.pr.1; for more information.</para>
	    </listitem>
	  </varlistentry>
	  
	  <varlistentry>
	    <term><option>-T <replaceable>title</replaceable></option></term>
	    
	    <listitem>
	      <para>Use <replaceable>title</replaceable> on the
		  &man.pr.1; 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 &man.ls.1; manual page on the default printer:</para>
	    
	<screen>&prompt.user; <userinput>zcat /usr/share/man/man1/ls.1.gz | troff -t -man | lpr -t</userinput></screen>
	      
	<para>The &man.zcat.1; command uncompresses the source of the
	  &man.ls.1; manual page and passes it to the &man.troff.1;
	  command, which formats that source and makes GNU troff
	  output and passes it to &man.lpr.1;, which submits the job
	  to the <application>LPD</application> spooler.  Because we 
	  used the <option>-t</option>
	  option to &man.lpr.1;, 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 &man.lpr.1; tell 
	  <application>LPD</application> 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>
		      
	      <screen>&prompt.user; <userinput>lpr -#3 parser.c parser.h</userinput></screen>
	    </listitem>
	  </varlistentry>
	  
	  <varlistentry>
	    <term>-m</term>
	    
	    <listitem>
	      <para>Send mail after completing the print job.  With this
		option, the <application>LPD</application> 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 
		<application>LPD</application>
		will not have to copy each and every byte of your job to the
		spooling directory.</para>
		    
	      <para>There is a drawback, though: since 
		<application>LPD</application> 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, 
		  <application>LPD</application> 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 &man.lpr.1; 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>Administering Printers</title>
      
      <para>As an administrator for your printers, you have had to install,
	set up, and test them.  Using the &man.lpc.8; command, you
	can interact with your printers in yet more ways. With &man.lpc.8;,
	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
	<username>root</username>) 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 <username>root</username> privileges
	to use the &man.lpc.8; command.  Ordinary users can use the &man.lpc.8;
	command to get printer status and to restart a hung printer only.</para>

      <para>Here is a summary of the &man.lpc.8; commands.  Most of the
	commands take 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 is 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 <application>LPD</application>, 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 is running, it
	      will continue to print any jobs remaining in the queue.  The
	      superuser (<username>root</username>) 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
	      <username>root</username>.  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
		    &man.lpq.1; 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 
	      <application>LPD</application>, 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>&man.lpc.8; accepts the above commands on the command line.  If
	you do not enter any commands, &man.lpc.8; 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-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 
      <application>LPD</application>
      spooling system that comes with FreeBSD.  You can probably appreciate
      many of its shortcomings, which naturally leads to the question:
      <quote>What other spooling systems are out there (and work with
      FreeBSD)?</quote></para>

    <variablelist>
      <varlistentry>
	<term>LPRng</term>

 	<indexterm><primary>LPRng</primary></indexterm>	  
	<listitem>
	  <para><application>LPRng</application>, which purportedly means
	    <quote>LPR: the Next
	    Generation</quote> is a complete rewrite of PLP.  Patrick Powell
	    and Justin Mason (the principal maintainer of PLP) collaborated to
	    make <application>LPRng</application>.  The main site for 
	    <application>LPRng</application> is <ulink
	      url="http://www.lprng.org/"></ulink>.</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term>CUPS</term>

 	<indexterm><primary>CUPS</primary></indexterm>	  
	<listitem>
	  <para><application>CUPS</application>, the Common UNIX Printing
	    System, provides a portable printing layer for &unix;-based
	    operating systems.  It has been developed by Easy Software
	    Products to promote a standard printing solution for all &unix;
	    vendors and users.</para>

	  <para><application>CUPS</application> uses the Internet Printing
	    Protocol (<acronym>IPP</acronym>) as the basis for managing
	    print jobs and queues.  The Line Printer Daemon
	    (<acronym>LPD</acronym>) Server Message Block
	    (<acronym>SMB</acronym>), and AppSocket (a.k.a. JetDirect)
	    protocols are also supported with reduced functionality.  CUPS
	    adds network printer browsing and PostScript Printer Description
	    (<acronym>PPD</acronym>) based printing options to support
	    real-world printing under &unix;.</para>

	  <para>The main site for <application>CUPS</application> is <ulink
	    url="http://www.cups.org/"></ulink>.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </sect1>

  <sect1 id="printing-troubleshooting">
    <title>Troubleshooting</title>

    <para>After performing the simple test with &man.lptest.1;, 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 <quote>staircase effect.</quote></term>

	<listitem>
	  <para>You got the following on paper:</para>

	  <programlisting>!"#$%&amp;'()*+,-./01234
                "#$%&amp;'()*+,-./012345
                                 #$%&amp;'()*+,-./0123456</programlisting>

	  <indexterm><primary>MS-DOS</primary></indexterm>
 	  <indexterm><primary>OS/2</primary></indexterm>
 	  <indexterm><primary>ASCII</primary></indexterm>
	  <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;, &os2;, 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, use the <literal>ms#</literal> capability and
		set the <literal>onlcr</literal> mode
		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>

	      <indexterm><primary>PCL</primary></indexterm>
	      <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.  Ejects the page when done.

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 <hostid>orchid</hostid>.  It has a single printer
		attached to its first parallel port, a Hewlett Packard
		LaserJet 3Si named <literal>teak</literal>.  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 <quote>opposite</quote> 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 <literal>ixon</literal> mode
		in the <literal>ms#</literal> capability.</para>
	    </listitem>

	    <listitem>
	      <para>If the printer supports carrier flow control, specify
		the <literal>crtscts</literal> mode in the 
		<literal>ms#</literal> capability.
		Make sure the cable connecting the printer to the computer
		is correctly wired for carrier flow control.</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 setting in the
	    <literal>ms#</literal> capability; 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,
	    <application>LPD</application> uses 
	    <filename>/dev/console</filename> as a default.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </sect1>
</chapter>

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