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<chapter id="printing">
<title>Printing</title>
<para><emphasis>Contributed by &a.kelly;, 30 September 1995.
Restructured and updated by &a.jim;, March 2000.</emphasis></para>
<sect1>
<title>Synopsis</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 LPD spooling system. It is the standard printer
control system in FreeBSD. This chapter introduces the LPD spooling
system, often simply called LPD, and will guide you through it's
configuration.</para>
<para>If you are already familiar with LPD or another printer spooling
system, you may wish to skip to section <link
linkend="printing-intro-setup">Setting up the spooling
system</link>.</para>
</sect1>
<sect1 id="printing-intro-spooler">
<title>Introduction</title>
<para>LPD controls everything about a host's printers. It is
responsible for a number of things:</para>
<itemizedlist>
<listitem>
<para>It controls access to attached printers and printers
attached to other hosts on the network.</para>
</listitem>
<listitem>
<para>It enables users to submit files to be printed; these
submissions are known as <emphasis>jobs</emphasis>.</para>
</listitem>
<listitem>
<para>It prevents multiple users from accessing a printer at the
same time by maintaining a <emphasis>queue</emphasis> for each
printer.</para>
</listitem>
<listitem>
<para>It can print <emphasis>header pages</emphasis> (also known
as <emphasis>banner</emphasis> or <emphasis>burst</emphasis>
pages) so users can easily find jobs they have printed in a
stack of printouts.</para>
</listitem>
<listitem>
<para>It takes care of communications parameters for printers
connected on serial ports.</para>
</listitem>
<listitem>
<para>It can send jobs over the network to another LPD spooler on
another host.</para>
</listitem>
<listitem>
<para>It can run special filters to format jobs to be printed for
various printer languages or printer capabilities.</para>
</listitem>
<listitem>
<para>It can account for printer usage.</para>
</listitem>
</itemizedlist>
<para>Through a configuration file
(<filename>/etc/printcap</filename>), and by providing the special
filter programs, you can enable the LPD system to do all or some
subset of the above for a great variety of printer hardware.</para>
<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>LPD prints jobs in the background; you do not have to wait
for data to be copied to the printer.</para>
</listitem>
<listitem>
<para>LPD can conveniently run a job to be printed through
filters to add date/time headers or convert a special file
format (such as a TeX DVI file) into a format the printer will
understand. You will not have to do these steps
manually.</para>
</listitem>
<listitem>
<para>Many free and commercial programs that provide a print
feature usually expect to talk to the spooler on your system.
By setting up the spooling system, you will more easily
support other software you may later add or already
have.</para>
</listitem>
</itemizedlist>
</sect2>
</sect1>
<sect1 id="printing-intro-setup">
<title>Basic Setup</title>
<para>To use printers with the LPD spooling system, you will need to
set up both your printer hardware and the LPD software. This
document describes two levels of setup:</para>
<itemizedlist>
<listitem>
<para>See section <link linkend="printing-simple">Simple Printer
Setup</link> to learn how to connect a printer, tell LPD how to
communicate with it, and print plain text files to the
printer.</para>
</listitem>
<listitem>
<para>See section <link linkend="printing-advanced">Advanced
Printer Setup</link> to find out how to print a variety of
special file formats, to print header pages, to print across a
network, to control access to printers, and to do printer
accounting.</para>
</listitem>
</itemizedlist>
<sect2 id="printing-simple">
<title>Simple Printer Setup</title>
<para>This section tells how to configure printer hardware and the
LPD software to use the printer. It teaches the basics:</para>
<itemizedlist>
<listitem>
<para>Section <link linkend="printing-hardware">Hardware
Setup</link> gives some hints on connecting the printer to a
port on your computer.</para>
</listitem>
<listitem>
<para>Section <link linkend="printing-software">Software
Setup</link> shows how to setup the LPD spooler configuration
file (<filename>/etc/printcap</filename>).</para>
</listitem>
</itemizedlist>
<para>If you are setting up a printer that uses a network protocol
to accept data to print instead of a serial or parallel interface,
see <link linkend="printing-advanced-network-net-if">Printers With
Networked Data Stream Interaces</link>.</para>
<para>Although this section is called <quote>Simple Printer
Setup</quote>, it is actually fairly complex. Getting the printer
to work with your computer and the LPD spooler is the hardest
part. The advanced options like header pages and accounting are
fairly easy once you get the printer working.</para>
<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>Nearly all printers you can get for a PC today support one
or both of the following interfaces:</para>
<itemizedlist>
<listitem>
<para><emphasis>Serial</emphasis> interfaces use a serial
port on your computer to send data to the printer. Serial
interfaces are common in the computer industry and cables
are readily available and also easy to construct. Serial
interfaces sometimes need special cables and might require
you to configure somewhat complex communications
options.</para>
</listitem>
<listitem>
<para><emphasis>Parallel</emphasis> interfaces use a
parallel port on your computer to send data to the
printer. Parallel interfaces are common in the PC market.
Cables are readily available but more difficult to
construct by hand. There are usually no communications
options with parallel interfaces, making their
configuration exceedingly simple.</para>
<para>Parallel interfaces are sometimes known as
<quote>Centronics</quote> interfaces, named after the
connector type on the printer.</para>
</listitem>
</itemizedlist>
<para>In general, serial interfaces are slower than parallel
interfaces. Parallel interfaces usually offer just one-way
communication (computer to printer) while serial gives you
two-way. Many newer parallel ports can also receive data from
the printer, but only few printers need to send data back to
the computer. And FreeBSD does not support two-way parallel
communication yet.</para>
<para>Usually, the only time you need two-way communication with
the printer is if the printer speaks PostScript. PostScript
printers can be very verbose. In fact, PostScript jobs are
actually programs sent to the printer; they need not produce
paper at all and may return results directly to the computer.
PostScript also uses two-way communication to tell the
computer about problems, such as errors in the PostScript
program or paper jams. Your users may be appreciative of such
information. Furthermore, the best way to do effective
accounting with a PostScript printer requires two-way
communication: you ask the printer for its page count (how
many pages it has printed in its lifetime), then send the
user's job, then ask again for its page count. Subtract the
two values and you know how much paper to charge the
user.</para>
</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/lpt0</filename> to
FreeBSD; the second is <filename>/dev/lpt1</filename>, and so
on.</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>
<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>
<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 LPD spooling system in FreeBSD.</para>
<para>Here is an outline of the steps involved:</para>
<procedure>
<step>
<para>Configure your kernel, if necessary, for the port you
are using for the printer; section <link
linkend="printing-kernel">Kernel Configuration</link> tells
you what you need to do.</para>
</step>
<step>
<para>Set the communications mode for the parallel port, if
you are using a parallel port; section <link
linkend="printing-parallel-port-mode">Setting the
Communication Mode for the Parallel Port</link> gives
details.</para>
</step>
<step>
<para>Test if the operating system can send data to the printer.
Section <link linkend="printing-testing">Checking Printer
Communications</link> gives some suggestions on how to do
this.</para>
</step>
<step>
<para>Set up LPD for the printer by modifying the file
<filename>/etc/printcap</filename>. 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>dmesg | grep sio<replaceable>N</replaceable></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 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>dmesg | grep lpt<replaceable>N</replaceable></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 <screen>lpt0 at 0x378-0x37f on isa</screen>
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>
<para>Even though the kernel may support communication along a
serial or parallel port, you will still need a software
interface through which programs running on the system can
send and receive data. That is what entries in the
<filename>/dev</filename> directory are for.</para>
<para><emphasis>To add a <filename>/dev</filename> entry for a
port:</emphasis></para>
<procedure>
<step>
<para>Become root with the &man.su.1; command. Enter the
root password when prompted.</para>
</step>
<step>
<para>Change to the <filename>/dev</filename>
directory:</para>
<screen>&prompt.root; cd <filename>/dev</filename></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 first parallel port,
<literal>lpt1</literal> for the second, and so on; use
<literal>ttyd0</literal> for the first serial port,
<literal>ttyd1</literal> for the second, and so on.</para>
</step>
<step>
<para>Type:</para>
<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.</para>
<itemizedlist>
<listitem>
<para>The <emphasis>interrupt-driven</emphasis> method is
the default with the GENERIC kernel. With this method,
the operating system uses an IRQ line to determine when
the printer is ready for data.</para>
</listitem>
<listitem>
<para>The <emphasis>polled</emphasis> method directs the
operating system to repeatedly ask the printer if it is
ready for more data. When it responds ready, the kernel
sends more data.</para>
</listitem>
</itemizedlist>
<para>The interrupt-driven method is somewhat faster but uses up
a precious IRQ line. You should use whichever one
works.</para>
<para>You can set the communications mode in two ways: by
configuring the kernel or by using the &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 or add
an <literal>lpt0</literal> entry. If you are setting up
the second parallel port, use <literal>lpt1</literal>
instead. Use <literal>lpt2</literal> for the third port,
and so on.</para>
<itemizedlist>
<listitem>
<para>If you want interrupt-driven mode, add the
<literal>irq</literal> specifier:</para>
<programlisting>
device lpt0 at isa? port? tty irq <replaceable>N</replaceable> vector lptintr</programlisting>
<para>Where <replaceable>N</replaceable> is the IRQ
number for your computer's parallel port.</para>
</listitem>
<listitem>
<para>If you want polled mode, do not add the
<literal>irq</literal> specifier:</para>
<programlisting>
device lpt0 at isa? port? tty vector lptintr</programlisting>
</listitem>
</itemizedlist>
</step>
<step>
<para>Save the file. Then configure, build, and install the
kernel, then reboot. See <link
linkend="kernelconfig">kernel configuration</link> for
more details.</para>
</step>
</procedure>
<para><emphasis>To set the communications mode with</emphasis>
&man.lptcontrol.8;:</para>
<procedure>
<step>
<para>Type:</para>
<screen>&prompt.root; <userinput>lptcontrol -i -u <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 -u <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>
<para>For a PostScript (or other language-based) printer, we
will need a more sophisticated test. A small PostScript
program, such as the following, will suffice:</para>
<programlisting>
%!PS
100 100 moveto 300 300 lineto stroke
310 310 moveto /Helvetica findfont 12 scalefont setfont
(Is this thing working?) show
showpage</programlisting>
<note>
<para>When this document refers to a printer language, 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>
<para>This section tells you how to check if FreeBSD can
communicate with a printer connected to a parallel
port.</para>
<para><emphasis>To test a printer on a parallel
port:</emphasis></para>
<procedure>
<step>
<para>Become root with &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 > /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 > /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> > /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>
<para>This section tells you how to check if FreeBSD can
communicate with a printer on a serial port.</para>
<para><emphasis>To test a printer on a serial
port:</emphasis></para>
<procedure>
<step>
<para>Become root with &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>
<para>Where <replaceable>port</replaceable> is the device
entry for the serial port (<literal>ttyd0</literal>,
<literal>ttyd1</literal>, etc.),
<replaceable>bps-rate</replaceable> is the
bits-per-second rate at which the printer communicates,
and <replaceable>parity</replaceable> is the parity
required by the printer (either <literal>even</literal>,
<literal>odd</literal>, <literal>none</literal>, or
<literal>zero</literal>).</para>
<para>Here is a sample entry for a printer connected via
a serial line to the third serial port at 19200 bps with
no parity:</para>
<programlisting>
printer:dv=/dev/ttyd2:br#19200:pa=none</programlisting>
</step>
<step>
<para>Connect to the printer with &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>~</prompt><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>~</prompt><userinput>><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 LPD to control access to your printer.</para>
<para>You configure LPD by editing the file
<filename>/etc/printcap</filename>. The LPD spooling system
reads this file each time the spooler is used, so updates to the
file take immediate effect.</para>
<para>The format of the &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>
<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>fs</literal>, <literal>fc</literal>,
<literal>xs</literal>, and <literal>xc</literal>
capabilities; 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 LPD to do their printing usually make the same assumption.
If you are installing such a printer and want to be able to
print jobs in the printer language <emphasis>and</emphasis>
print plain text jobs, you are strongly urged to add an
additional step to the simple setup outlined above: install an
automatic plain-text-to-PostScript (or other printer language)
conversion program. 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 aliases
for the printer.</para>
<para>At least one of the printers specified in the
<filename>/etc/printcap</filename> should have the alias
<literal>lp</literal>. This is the default printer's name.
If users do not have the <envar>PRINTER</envar> environment
variable nor specify a printer name on the command line of any
of the LPD commands, then <literal>lp</literal> will be the
default printer they get to use.</para>
<para>Also, it is common practice to make the last alias for a
printer be a full description of the printer, including make
and model.</para>
<para>Once you have picked a name and some common aliases, put
them in the <filename>/etc/printcap</filename> file. The name
of the printer should start in the leftmost column. Separate
each alias with a vertical bar and put a colon after the last
alias.</para>
<para>In the following example, we start with a skeletal
<filename>/etc/printcap</filename> that defines two printers
(a Diablo 630 line printer and a Panasonic KX-P4455 PostScript
laser printer):</para>
<programlisting>
#
# /etc/printcap for host rose
#
rattan|line|diablo|lp|Diablo 630 Line Printer:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:</programlisting>
<para>In this example, the first printer is named
<literal>rattan</literal> and has as aliases
<literal>line</literal>, <literal>diablo</literal>,
<literal>lp</literal>, and <literal>Diablo 630 Line
Printer</literal>. Since it has the alias
<literal>lp</literal>, it is also the default printer. The
second is named <literal>bamboo</literal>, and has as aliases
<literal>ps</literal>, <literal>PS</literal>,
<literal>S</literal>, <literal>panasonic</literal>, and
<literal>Panasonic KX-P4455 PostScript v51.4</literal>.</para>
</sect4>
<sect4 id="printing-no-header-pages">
<title>Suppressing Header Pages</title>
<para>The LPD spooling system will by default print a
<emphasis>header page</emphasis> for each job. The header
page contains the user name who requested the job, the host
from which the job came, and the name of the job, in nice
large letters. Unfortunately, all this extra text gets in the
way of debugging the simple printer setup, so we will suppress
header pages.</para>
<para>To suppress header pages, add the <literal>sh</literal>
capability to the entry for the printer in
<filename>/etc/printcap</filename>. Here is 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>
<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 LPD. 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 LPD about these directories
using the <filename>/etc/printcap</filename> file. You
specify the pathname of the spooling directory with the
<literal>sd</literal> capability:</para>
<programlisting>
#
# /etc/printcap for host rose - added spooling directories
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:</programlisting>
<para>Note that the name of the printer starts in the first
column but all other entries describing the printer should be
indented with a tab and each line escaped with a
backslash.</para>
<para>If you do not specify a spooling directory with
<literal>sd</literal>, the spooling system will use
<filename>/var/spool/lpd</filename> as a default.</para>
</sect4>
<sect4 id="printing-device">
<title>Identifying the Printer Device</title>
<para>In 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 LPD that
information. When the spooling system has a job to print, it
will open the specified device on behalf of the filter program
(which is responsible for passing data to the printer).</para>
<para>List the <filename>/dev</filename> entry pathname in the
<filename>/etc/printcap</filename> file using the
<literal>lp</literal> capability.</para>
<para>In our running example, let us assume that
<hostid>rattan</hostid> is on the first parallel port, and
<hostid>bamboo</hostid> is on a sixth serial port; here are
the additions to <filename>/etc/printcap</filename>:</para>
<programlisting>
#
# /etc/printcap for host rose - identified what devices to use
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:\
:lp=/dev/ttyd5:</programlisting>
<para>If you do not specify the <literal>lp</literal> capability
for a printer in your <filename>/etc/printcap</filename> file,
LPD uses <filename>/dev/lp</filename> as a default.
<filename>/dev/lp</filename> currently does not exist in
FreeBSD.</para>
<para>If the printer you are installing is connected to a
parallel port, skip to the section 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>
<para>For printers on serial ports, LPD can set up the bps rate,
parity, and other serial communication parameters on behalf of
the filter program that sends data to the printer. This is
advantageous since:</para>
<itemizedlist>
<listitem>
<para>It lets you try different communication parameters by
simply editing the <filename>/etc/printcap</filename>
file; you do not have to recompile the filter
program.</para>
</listitem>
<listitem>
<para>It enables the spooling system to use the same filter
program for multiple printers which may have different
serial communication settings.</para>
</listitem>
</itemizedlist>
<para>The following <filename>/etc/printcap</filename>
capabilities control serial communication parameters of the
device listed in the <literal>lp</literal> capability:</para>
<variablelist>
<varlistentry>
<term><literal>br#<replaceable>bps-rate</replaceable></literal></term>
<listitem>
<para>Sets the communications speed of the device to
<replaceable>bps-rate</replaceable>, where
<replaceable>bps-rate</replaceable> can be 50, 75, 110,
134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600,
19200, or 38400 bits-per-second.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fc#<replaceable>clear-bits</replaceable></literal></term>
<listitem>
<para>Clears the flag bits
<replaceable>clear-bits</replaceable> in the
<replaceable>sgttyb</replaceable> structure after
opening the device.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fs#<replaceable>set-bits</replaceable></literal></term>
<listitem>
<para>Sets the flag bits
<replaceable>set-bits</replaceable> in the
<replaceable>sgttyb</replaceable> structure.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>xc#<replaceable>clear-bits</replaceable></literal></term>
<listitem>
<para>Clears local mode bits
<replaceable>clear-bits</replaceable> after opening the
device.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>xs#<replaceable>set-bits</replaceable></literal></term>
<listitem>
<para>Sets local mode bits
<replaceable>set-bits</replaceable>.</para>
</listitem>
</varlistentry>
</variablelist>
<para>For more information on the bits for the
<literal>fc</literal>, <literal>fs</literal>,
<literal>xc</literal>, and <literal>xs</literal> capabilities,
see the file
<filename>/usr/include/sys/ioctl_compat.h</filename>.</para>
<para>When LPD opens the device specified by the
<literal>lp</literal> capability, it reads the flag bits in
the <literal>sgttyb</literal> structure; it clears any bits in
the <literal>fc</literal> capability, then sets bits in the
<literal>fs</literal> capability, then applies the resultant
setting. It does the same for the local mode bits as
well.</para>
<para>Let us add to our example printer on the sixth serial
port. We will set the bps rate to 38400. For the flag bits,
we will set the <literal>TANDEM</literal>,
<literal>ANYP</literal>, <literal>LITOUT</literal>,
<literal>FLUSHO</literal>, and <literal>PASS8</literal> flags.
For the local mode bits, we will set the
<literal>LITOUT</literal> and <literal>PASS8</literal>
flags:</para>
<programlisting>
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:\
:lp=/dev/ttyd5:fs#0x82000c1:xs#0x820:</programlisting>
</sect4>
<sect4 id="printing-textfilter">
<title>Installing the Text Filter</title>
<para>We are now ready to tell LPD what text filter to use to
send jobs to the printer. A <emphasis>text filter</emphasis>,
also known as an <emphasis>input filter</emphasis>, is a
program that LPD runs when it has a job to print. When LPD
runs the text filter for a printer, it sets the filter's
standard input to the job to print, and its standard output to
the printer device specified with the <literal>lp</literal>
capability. The filter is expected to read the job from
standard input, perform any necessary translation for the
printer, and write the results to standard output, which will
get printed. For more information on the text filter, see
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 && 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:fs#0x82000e1:xs#0x820:\
:if=/usr/local/libexec/if-simple:</programlisting>
</sect4>
<sect4>
<title>Turn on LPD</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 LPD setup.
Unfortunately, congratulations are not quite yet in order,
since we still have to test the setup and correct any
problems. To test the setup, try printing something. To
print with the LPD system, you use the command &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 LPD 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>
!"#$%&'()*+,-./01234
"#$%&'()*+,-./012345
#$%&'()*+,-./0123456
$%&'()*+,-./01234567
%&'()*+,-./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>
<para>Although LPD handles network protocols, queuing, access control,
and other aspects of printing, most of the <emphasis>real</emphasis>
work happens in the <emphasis>filters</emphasis>. Filters are
programs that communicate with the printer and handle its device
dependencies and special requirements. In the simple printer setup,
we installed a plain text filter—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 LPD uses filters. This knowledge could help you anticipate
and debug problems you might encounter as you install more and
more filters on each of your printers.</para>
</listitem>
<listitem>
<para>LPD expects every printer to be able to print plain text by
default. This presents a problem for PostScript (or other
language-based printers) which cannot directly print plain text.
Section <link
linkend="printing-advanced-if-conversion">Accommodating
Plain Text Jobs on PostScript Printers</link> tells you what you
should do to overcome this problem. I recommend reading this
section if you have a PostScript printer.</para>
</listitem>
<listitem>
<para>PostScript is a popular output format for many programs. Even
some people (myself included) write PostScript code directly. But
PostScript printers are expensive. Section <link
linkend="printing-advanced-ps">Simulating PostScript on
Non-PostScript Printers</link> tells how you can further modify
a printer's text filter to accept and print PostScript data on a
<emphasis>non-PostScript</emphasis> printer. I recommend reading
this section if you do not have a PostScript printer.</para>
</listitem>
<listitem>
<para>Section <link
linkend="printing-advanced-convfilters">Conversion
Filters</link> tells about a way you can automate the conversion
of specific file formats, such as graphic or typesetting data,
into formats your printer can understand. After reading this
section, you should be able to set up your printers such that
users can type <command>lpr -t</command> to print troff data, or
<command>lpr -d</command> to print TeX DVI data, or <command>lpr
-v</command> to print raster image data, and so forth. I
recommend reading this section.</para>
</listitem>
<listitem>
<para>Section <link linkend="printing-advanced-of">Output
Filters</link> tells all about a not often used feature of LPD:
output filters. Unless you are printing header pages (see <link
linkend="printing-advanced-header-pages">Header Pages</link>),
you can probably skip that section altogether.</para>
</listitem>
<listitem>
<para>Section <link linkend="printing-advanced-lpf">lpf: a Text
Filter</link> describes <command>lpf</command>, a fairly
complete if simple text filter for line printers (and laser
printers that act like line printers) that comes with FreeBSD. If
you need a quick way to get printer accounting working for plain
text, or if you have a printer which emits smoke when it sees
backspace characters, you should definitely consider
<command>lpf</command>.</para>
</listitem>
</itemizedlist>
<sect3 id="printing-advanced-filters">
<title>How Filters Work</title>
<para>As mentioned before, a filter is an executable program started
by LPD to handle the device-dependent part of communicating with the
printer.</para>
<para>When LPD wants to print a file in a job, it starts a filter
program. It sets the filter's standard input to the file to print,
its standard output to the printer, and its standard error to the
error logging file (specified in the <literal>lf</literal>
capability in <filename>/etc/printcap</filename>, or
<filename>/dev/console</filename> by default).</para>
<para>Which filter LPD starts and the filter's arguments depend on
what is listed in the <filename>/etc/printcap</filename> file and
what arguments the user specified for the job on the
&man.lpr.1; command line. For example, if the user typed
<command>lpr -t</command>, LPD would start the troff filter, listed
in the <literal>tf</literal> capability for the destination printer.
If the user wanted to print plain text, it would start the
<literal>if</literal> filter (this is mostly true: see <link
linkend="printing-advanced-of">Output Filters</link> for
details).</para>
<para>There are three kinds of filters you can specify in
<filename>/etc/printcap</filename>:</para>
<itemizedlist>
<listitem>
<para>The <emphasis>text filter</emphasis>, confusingly called the
<emphasis>input filter</emphasis> in LPD documentation, handles
regular text printing. Think of it as the default filter. LPD
expects every printer to be able to print plain text by default,
and it is the text filter's job to make sure backspaces, tabs,
or other special characters do not confuse the printer. If you
are in an environment where you have to account for printer
usage, the text filter must also account for pages printed,
usually by counting the number of lines printed and comparing
that to the number of lines per page the printer supports. The
text filter is started with the following argument list:
<cmdsynopsis>
<command>filter-name</command>
<arg>-c</arg>
<arg choice="plain">-w<replaceable>width</replaceable></arg>
<arg choice="plain">-l<replaceable>length</replaceable></arg>
<arg choice="plain">-i<replaceable>indent</replaceable></arg>
<arg choice="plain">-n <replaceable>login</replaceable></arg>
<arg choice="plain">-h <replaceable>host</replaceable></arg>
<arg choice="plain"><replaceable>acct-file</replaceable></arg>
</cmdsynopsis>
where
<variablelist>
<varlistentry>
<term><option>-c</option></term>
<listitem>
<para>appears if the job's submitted with <command>lpr
-l</command></para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>width</replaceable></term>
<listitem>
<para>is the value from the <literal>pw</literal> (page
width) capability specified in
<filename>/etc/printcap</filename>, default 132</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>length</replaceable></term>
<listitem>
<para>is the value from the <literal>pl</literal> (page
length) capability, default 66</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>indent</replaceable></term>
<listitem>
<para>is the amount of the indentation from <command>lpr
-i</command>, default 0</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>login</replaceable></term>
<listitem>
<para>is the account name of the user printing the
file</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>host</replaceable></term>
<listitem>
<para>is the host name from which the job was
submitted</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>acct-file</replaceable></term>
<listitem>
<para>is the name of the accounting file from the
<literal>af</literal> capability.</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
<listitem>
<para>A <emphasis>conversion filter</emphasis> converts a specific
file format into one the printer can render onto paper. For
example, ditroff typesetting data cannot be directly printed,
but you can install a conversion filter for ditroff files to
convert the ditroff data into a form the printer can digest and
print. Section <link
linkend="printing-advanced-convfilters">Conversion
Filters</link> tells all about them. Conversion filters also
need to do accounting, if you need printer accounting.
Conversion filters are started with the following arguments:
<cmdsynopsis>
<command>filter-name</command>
<arg
choice="plain">-x<replaceable>pixel-width</replaceable></arg>
<arg choice="plain">-y<replaceable>pixel-height</replaceable></arg>
<arg choice="plain">-n <replaceable>login</replaceable></arg>
<arg choice="plain">-h <replaceable>host</replaceable></arg>
<arg choice="plain"><replaceable>acct-file</replaceable></arg>
</cmdsynopsis>
where <replaceable>pixel-width</replaceable> is the value
from the <literal>px</literal> capability (default 0) and
<replaceable>pixel-height</replaceable> is the value from the
<literal>py</literal> capability (default 0).</para>
</listitem>
<listitem>
<para>The <emphasis>output filter</emphasis> is used only if there
is no text filter, or if header pages are enabled. In my
experience, output filters are rarely used. Section <link
linkend="printing-advanced-of">Output Filters</link> describe
them. There are only two arguments to an output filter:
<cmdsynopsis>
<command>filter-name</command>
<arg choice="plain">-w<replaceable>width</replaceable></arg>
<arg choice="plain">-l<replaceable>length</replaceable></arg>
</cmdsynopsis>
which are identical to the text filters <option>-w</option> and
<option>-l</option> arguments.</para>
</listitem>
</itemizedlist>
<para>Filters should also <emphasis>exit</emphasis> with the
following exit status:</para>
<variablelist>
<varlistentry>
<term>exit 0</term>
<listitem>
<para>If the filter printed the file successfully.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>exit 1</term>
<listitem>
<para>If the filter failed to print the file but wants LPD to
try to print the file again. LPD will restart a filter if it
exits with this status.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>exit 2</term>
<listitem>
<para>If the filter failed to print the file and does not want
LPD to try again. LPD will throw out the file.</para>
</listitem>
</varlistentry>
</variablelist>
<para>The text filter that comes with the FreeBSD release,
<filename>/usr/libexec/lpr/lpf</filename>, takes advantage of the
page width and length arguments to determine when to send a form
feed and how to account for printer usage. It uses the login, host,
and accounting file arguments to make the accounting entries.</para>
<para>If you are shopping for filters, see if they are LPD-compatible.
If they are, they must support the argument lists described above.
If you plan on writing filters for general use, then have them
support the same argument lists and exit codes.</para>
</sect3>
<sect3 id="printing-advanced-if-conversion">
<title>Accommodating Plain Text Jobs on PostScript Printers</title>
<para>If you are the only user of your computer and PostScript (or
other language-based) printer, and you promise to never send plain
text to your printer and to never use features of various programs
that will want to send plain text to your printer, then you do not
need to worry about this section at all.</para>
<para>But, if you would like to send both PostScript and plain text
jobs to the printer, then you are urged to augment your printer
setup. To do so, we have the text filter detect if the arriving job
is plain text or PostScript. All PostScript jobs must start with
<literal>%!</literal> (for other printer languages, see your printer
documentation). If those are the first two characters in the job,
we have PostScript, and can pass the rest of the job directly. If
those are not the first two characters in the file, then the filter
will convert the text into PostScript and print the result.</para>
<para>How do we do this?</para>
<para>If you have got a serial printer, a great way to do it is to
install <command>lprps</command>. <command>lprps</command> is a
PostScript printer filter which performs two-way communication with
the printer. It updates the printer's status file with verbose
information from the printer, so users and administrators can see
exactly what the state of the printer is (such as <errorname>toner
low</errorname> or <errorname>paper jam</errorname>). But more
importantly, it includes a program called <command>psif</command>
which detects whether the incoming job is plain text and calls
<command>textps</command> (another program that comes with
<command>lprps</command>) to convert it to PostScript. It then uses
<command>lprps</command> to send the job to the printer.</para>
<para><command>lprps</command> is part of the FreeBSD ports collection
(see <link linkend="ports">The Ports Collection</link>). You can
fetch, build and install it yourself, of course. After installing
<command>lprps</command>, just specify the pathname to the
<command>psif</command> program that is part of
<command>lprps</command>. If you installed <command>lprps</command>
from the ports collection, use the following in the serial
PostScript printer's entry in
<filename>/etc/printcap</filename>:</para>
<programlisting>
:if=/usr/local/libexec/psif:</programlisting>
<para>You should also specify the <literal>rw</literal> capability;
that tells LPD to open the printer in read-write mode.</para>
<para>If you have a parallel PostScript printer (and therefore cannot
use two-way communication with the printer, which
<command>lprps</command> needs), you can use the following shell
script as the text filter:</para>
<programlisting>
#!/bin/sh
#
# psif - Print PostScript or plain text on a PostScript printer
# Script version; NOT the version that comes with lprps
# Installed in /usr/local/libexec/psif
#
read first_line
first_two_chars=`expr "$first_line" : '\(..\)'`
if [ "$first_two_chars" = "%!" ]; then
#
# PostScript job, print it.
#
echo "$first_line" && cat && printf "\004" && exit 0
exit 2
else
#
# Plain text, convert it, then print it.
#
( echo "$first_line"; cat ) | /usr/local/bin/textps && printf "\004" && 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>
<para>PostScript is the <emphasis>de facto</emphasis> standard for
high quality typesetting and printing. PostScript is, however, an
<emphasis>expensive</emphasis> standard. Thankfully, Alladin
Enterprises has a free PostScript work-alike called
<application>Ghostscript</application> that runs with FreeBSD.
Ghostscript can read most PostScript files and can render their
pages onto a variety of devices, including many brands of
non-PostScript printers. By installing Ghostscript and using a
special text filter for your printer, you can make your
non-PostScript printer act like a real PostScript printer.</para>
<para>Ghostscript should be in the FreeBSD ports collection, if you
would like to install it from there. You can fetch, build, and
install it quite easily yourself, as well.</para>
<para>To simulate PostScript, we have the text filter detect if it is
printing a PostScript file. If it is not, then the filter will pass
the file directly to the printer; otherwise, it will use Ghostscript
to first convert the file into a format the printer will
understand.</para>
<para>Here is an example: the following script is a text filter
for Hewlett Packard DeskJet 500 printers. For other printers,
substitute the <option>-sDEVICE</option> argument to the
<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/hpif
#
# Treat LF as CR+LF:
#
printf "\033&k2G" || exit 2
#
# Read first two characters of the file
#
read first_line
first_two_chars=`expr "$first_line" : '\(..\)'`
if [ "$first_two_chars" = "%!" ]; then
#
# It is PostScript; use Ghostscript to scan-convert and print it.
#
# Note that PostScript files are actually interpreted programs,
# and those programs are allowed to write to stdout, which will
# mess up the printed output. So, we redirect stdout to stderr
# and then make descriptor 3 go to stdout, and have Ghostscript
# write its output there. Exercise for the clever reader:
# capture the stderr output from Ghostscript and mail it back to
# the user originating the print job.
#
exec 3>&1 1>&2
/usr/local/bin/gs -dSAFER -dNOPAUSE -q -sDEVICE=djet500 \
-sOutputFile=/dev/fd/3 - && exit 0
#
/usr/local/bin/gs -dSAFER -dNOPAUSE -q -sDEVICE=djet500 -sOutputFile=- - \
&& exit 0
else
#
# Plain text or HP/PCL, so just print it directly; print a form
# at the end to eject the last page.
#
echo $first_line && cat && printf "\033&l0H" &&
exit 0
fi
exit 2</programlisting>
<para>Finally, you need to notify LPD of the filter via the
<literal>if</literal> capability:</para>
<programlisting>
:if=/usr/local/libexec/hpif:</programlisting>
<para>That is it. You can type <command>lpr plain.text</command> and
<filename>lpr whatever.ps</filename> and both should print
successfully.</para>
</sect3>
<sect3 id="printing-advanced-convfilters">
<title>Conversion Filters</title>
<para>After completing the simple setup described in <link
linkend="printing-simple">Simple Printer Setup</link>, the first
thing you will probably want to do is install conversion filters for
your favorite file formats (besides plain ASCII text).</para>
<sect4>
<title>Why Install Conversion Filters?</title>
<para>Conversion filters make printing various kinds of files easy.
As an example, suppose we do a lot of work with the TeX
typesetting system, and we have a PostScript printer. Every time
we generate a DVI file from TeX, we cannot print it directly until
we convert the DVI file into PostScript. The command sequence
goes like this:</para>
<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 LPD 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 LPD to do the DVI file conversion for us by specifying
the <option>-d</option> option. Section <link
linkend="printing-lpr-options-format">Formatting and Conversion
Options</link> lists the conversion options.</para>
<para>For each of the conversion options you want a printer to
support, install a <emphasis>conversion filter</emphasis> and
specify its pathname in <filename>/etc/printcap</filename>. A
conversion filter is like the text filter for the simple printer
setup (see section <link linkend="printing-textfilter">Installing
the Text Filter</link>) except that instead of printing plain
text, the filter converts the file into a format the printer can
understand.</para>
</sect4>
<sect4>
<title>Which Conversions Filters Should I Install?</title>
<para>You should install the conversion filters you expect to use.
If you print a lot of DVI data, then a DVI conversion filter is in
order. If you have got plenty of troff to print out, then you
probably want a troff filter.</para>
<para>The following table summarizes the filters that LPD works
with, their capability entries for the
<filename>/etc/printcap</filename> file, and how to invoke them
with the <command>lpr</command> command:</para>
<informaltable frame="none">
<tgroup cols="3">
<thead>
<row>
<entry>File type</entry>
<entry><filename>/etc/printcap</filename> capability</entry>
<entry><command>lpr</command> option</entry>
</row>
</thead>
<tbody>
<row>
<entry>cifplot</entry>
<entry><literal>cf</literal></entry>
<entry><option>-c</option></entry>
</row>
<row>
<entry>DVI</entry>
<entry><literal>df</literal></entry>
<entry><option>-d</option></entry>
</row>
<row>
<entry>plot</entry>
<entry><literal>gf</literal></entry>
<entry><option>-g</option></entry>
</row>
<row>
<entry>ditroff</entry>
<entry><literal>nf</literal></entry>
<entry><option>-n</option></entry>
</row>
<row>
<entry>FORTRAN text</entry>
<entry><literal>rf</literal></entry>
<entry><option>-f</option></entry>
</row>
<row>
<entry>troff</entry>
<entry><literal>rf</literal></entry>
<entry><option>-f</option></entry>
</row>
<row>
<entry>raster</entry>
<entry><literal>vf</literal></entry>
<entry><option>-v</option></entry>
</row>
<row>
<entry>plain text</entry>
<entry><literal>if</literal></entry>
<entry>none, <option>-p</option>, or
<option>-l</option></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>In our example, using <command>lpr -d</command> means the
printer needs a <literal>df</literal> capability in its entry in
<filename>/etc/printcap</filename>.</para>
<para>Despite what others might contend, formats like FORTRAN text
and plot are probably obsolete. At your site, you can give new
meanings to these or any of the formatting options just by
installing custom filters. For example, suppose you would like to
directly print Printerleaf files (files from the Interleaf desktop
publishing program), but will never print plot files. You could
install a Printerleaf conversion filter under the
<literal>gf</literal> capability and then educate your users that
<command>lpr -g</command> mean <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 LPD will run;
regular users should not ever need to run them.</para>
<para>To enable a conversion filter, specify its pathname under the
appropriate capability for the destination printer in
<filename>/etc/printcap</filename>.</para>
<para>In our example, we will add the DVI conversion filter to the
entry for the printer named <literal>bamboo</literal>. Here is
the example <filename>/etc/printcap</filename> file again, with
the new <literal>df</literal> capability for the printer
<literal>bamboo</literal>.</para>
<programlisting>
#
# /etc/printcap for host rose - added df filter for bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:\
:if=/usr/local/libexec/if-simple:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:\
:lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:</programlisting>
<para>The DVI filter is a shell script named
<filename>/usr/local/libexec/psdf</filename>. Here is that
script:</para>
<programlisting>
#!bin/sh
#
# psdf - DVI to PostScript printer filter
# Installed in /usr/local/libexec/psdf
#
# Invoked by lpd when user runs lpr -d
#
exec /usr/local/bin/dvips -f | /usr/local/libexec/lprps "$@"</programlisting>
<para>This script runs <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 LPD
passed to this script. <command>lprps</command> will use those
arguments to account for the pages printed.</para>
</sect4>
<sect4>
<title>More Conversion Filter Examples</title>
<para>Since there is no fixed set of steps to install conversion
filters, let me instead provide more examples. Use these as
guidance to making your own filters. Use them directly, if
appropriate.</para>
<para>This example script is a raster (well, GIF file, actually)
conversion filter for a Hewlett Packard LaserJet III-Si
printer:</para>
<programlisting>
#!/bin/sh
#
# hpvf - Convert GIF files into HP/PCL, then print
# Installed in /usr/local/libexec/hpvf
PATH=/usr/X11R6/bin:$PATH; export PATH
giftopnm | ppmtopgm | pgmtopbm | pbmtolj -resolution 300 \
&& exit 0 \
|| exit 2</programlisting>
<para>It works by converting the GIF file into a portable anymap,
converting that into a portable graymap, converting that into a
portable bitmap, and converting that into LaserJet/PCL-compatible
data.</para>
<para>Here is the <filename>/etc/printcap</filename> file with an
entry for a printer using the above filter:</para>
<programlisting>
#
# /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sh:sd=/var/spool/lpd/teak:mx#0:\
:if=/usr/local/libexec/hpif:\
:vf=/usr/local/libexec/hpvf:</programlisting>
<para>The following script is a conversion filter for troff data
from the groff typesetting system for the PostScript printer named
<literal>bamboo</literal>:</para>
<programlisting>
#!/bin/sh
#
# pstf - Convert groff's troff data into PS, then print.
# Installed in /usr/local/libexec/pstf
#
exec grops | /usr/local/libexec/lprps "$@"</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&k2G" && fpr && printf "\033&l0H" &&
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$$.dvi
}
#
# Define a function to handle fatal errors: print the given message
# and exit 2. Exiting with 2 tells LPD to do not try to reprint the
# job.
#
fatal() {
echo "$@" 1>&2
cleanup
exit 2
}
#
# If user removes the job, LPD will send SIGINT, so trap SIGINT
# (and a few other signals) to clean up after ourselves.
#
trap cleanup 1 2 15
#
# Make sure we are not colliding with any existing files.
#
cleanup
#
# Link the DVI input file to standard input (the file to print).
#
ln -s /dev/fd/0 hpdf$$.dvi || fatal "Cannot symlink /dev/fd/0"
#
# Make LF = CR+LF
#
printf "\033&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—and, of course, you can
still provide conversion filters just for them.</para>
<para>The FreeBSD ports collection has a text filter that performs
automatic conversion called <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 LPD spooling system supports one other type of filter that
we have not yet explored: an output filter. An output filter is
intended for printing plain text only, like the text filter, but
with many simplifications. If you are using an output filter but no
text filter, then:</para>
<itemizedlist>
<listitem>
<para>LPD starts an output filter once for the entire job instead
of once for each file in the job.</para>
</listitem>
<listitem>
<para>LPD does not make any provision to identify the start or the
end of files within the job for the output filter.</para>
</listitem>
<listitem>
<para>LPD does not pass the user's login or host to the filter, so
it is not intended to do accounting. In fact, it gets only two
arguments:</para>
<cmdsynopsis>
<command>filter-name</command>
<arg choice="plain">-w<replaceable>width</replaceable></arg>
<arg choice="plain">-l<replaceable>length</replaceable></arg>
</cmdsynopsis>
<para>Where <replaceable>width</replaceable> is from the
<literal>pw</literal> capability and
<replaceable>length</replaceable> is from the
<literal>pl</literal> capability for the printer in
question.</para>
</listitem>
</itemizedlist>
<para>Do not be seduced by an output filter's simplicity. If you
would like each file in a job to start on a different page an output
filter <emphasis>will not work</emphasis>. Use a text filter (also
known as an input filter); see section <link
linkend="printing-textfilter">Installing the Text Filter</link>.
Furthermore, an output filter is actually <emphasis>more
complex</emphasis> in that it has to examine the byte stream being
sent to it for special flag characters and must send signals to
itself on behalf of LPD.</para>
<para>However, an output filter is <emphasis>necessary</emphasis> if
you want header pages and need to send escape sequences or other
initialization strings to be able to print the header page. (But it
is also <emphasis>futile</emphasis> if you want to charge header
pages to the requesting user's account, since LPD does not give any
user or host information to the output filter.)</para>
<para>On a single printer, LPD allows both an output filter and text
or other filters. In such cases, LPD will start the output filter
to print the header page (see section <link
linkend="printing-advanced-header-pages">Header Pages</link>)
only. LPD then expects the output filter to <emphasis>stop
itself</emphasis> by sending two bytes to the filter: ASCII 031
followed by ASCII 001. When an output filter sees these two bytes
(031, 001), it should stop by sending SIGSTOP to itself. When LPD's
done running other filters, it will restart the output filter by
sending SIGCONT to it.</para>
<para>If there is an output filter but <emphasis>no</emphasis> text
filter and LPD is working on a plain text job, LPD uses the output
filter to do the job. As stated before, the output filter will
print each file of the job in sequence with no intervening form
feeds or other paper advancement, and this is probably
<emphasis>not</emphasis> what you want. In almost all cases, you
need a text filter.</para>
<para>The program <command>lpf</command>, which we introduced earlier
as a text filter, can also run as an output filter. If you need a
quick-and-dirty output filter but do not want to write the byte
detection and signal sending code, try <command>lpf</command>. You
can also wrap <command>lpf</command> in a shell script to handle any
initialization codes the printer might require.</para>
</sect3>
<sect3 id="printing-advanced-lpf">
<title><command>lpf</command>: a Text Filter</title>
<para>The program <filename>/usr/libexec/lpr/lpf</filename> that comes
with FreeBSD binary distribution is a text filter (input filter)
that can indent output (job submitted with <command>lpr
-i</command>), allow literal characters to pass (job submitted
with <command>lpr -l</command>), adjust the printing position for
backspaces and tabs in the job, and account for pages printed. It
can also act like an output filter.</para>
<para><command>lpf</command> is suitable for many printing
environments. And although it has no capability to send
initialization sequences to a printer, it is easy to write a shell
script to do the needed initialization and then execute
<command>lpf</command>.</para>
<para>In order for <command>lpf</command> to do page accounting
correctly, it needs correct values filled in for the
<literal>pw</literal> and <literal>pl</literal> capabilities in the
<filename>/etc/printcap</filename> file. It uses these values to
determine how much text can fit on a page and how many pages were in
a user's job. For more information on printer accounting, see <link
linkend="printing-advanced-acct">Accounting for Printer
Usage</link>.</para>
</sect3>
</sect2>
<sect2 id="printing-advanced-header-pages">
<title>Header Pages</title>
<para>If you have <emphasis>lots</emphasis> of users, all of them using
various printers, then you probably want to consider <emphasis>header
pages</emphasis> as a necessary evil.</para>
<para>Header pages, also known as <emphasis>banner</emphasis> or
<emphasis>burst pages</emphasis> identify to whom jobs belong after
they are printed. They are usually printed in large, bold letters,
perhaps with decorative borders, so that in a stack of printouts they
stand out from the real documents that comprise users' jobs. They
enable users to locate their jobs quickly. The obvious drawback to a
header page is that it is yet one more sheet that has to be printed
for every job, their ephemeral usefulness lasting not more than a few
minutes, ultimately finding themselves in a recycling bin or rubbish
heap. (Note that header pages go with each job, not each file in a
job, so the paper waste might not be that bad.)</para>
<para>The LPD system can provide header pages automatically for your
printouts <emphasis>if</emphasis> your printer can directly print
plain text. If you have a PostScript printer, you will need an
external program to generate the header page; see <link
linkend="printing-advanced-header-pages-ps">Header Pages on
PostScript Printers</link>.</para>
<sect3 id="printing-advanced-header-pages-enabling">
<title>Enabling Header Pages</title>
<para>In the <link linkend="printing-simple">Simple Printer
Setup</link>, we turned off header pages by specifying
<literal>sh</literal> (meaning <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&k2G" || exit 2
exec /usr/libexec/lpr/lpf</programlisting>
<para>Specify the path to the output filter in the
<literal>of</literal> capability. See <link
linkend="printing-advanced-of">Output Filters</link> for more
information.</para>
<para>Here is an example <filename>/etc/printcap</filename> file for
the printer <literal>teak</literal> that we introduced earlier; we
enabled header pages and added the above output filter:</para>
<programlisting>
#
# /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:\
:if=/usr/local/libexec/hpif:\
:vf=/usr/local/libexec/hpvf:\
:of=/usr/local/libexec/hpof:</programlisting>
<para>Now, when users print jobs to <literal>teak</literal>, they get
a header page with each job. If users want to spend time searching
for their printouts, they can suppress header pages by submitting
the job with <command>lpr -h</command>; see <link
linkend="printing-lpr-options-misc">Header Page Options</link> for
more &man.lpr.1; options.</para>
<note>
<para>LPD prints a form feed character after the header page. If
your printer uses a different character or sequence of characters
to eject a page, specify them with the <literal>ff</literal>
capability in <filename>/etc/printcap</filename>.</para>
</note>
</sect3>
<sect3 id="printing-advanced-header-pages-controlling">
<title>Controlling Header Pages</title>
<para>By enabling header pages, LPD will produce a <emphasis>long
header</emphasis>, a full page of large letters identifying the
user, host, and job. Here is an example (kelly printed the job
named outline from host rose):</para>
<programlisting>
k ll ll
k l l
k l l
k k eeee l l y y
k k e e l l y y
k k eeeeee l l y y
kk k e l l y y
k k e e l l y yy
k k eeee lll lll yyy y
y
y y
yyyy
ll
t l i
t l
oooo u u ttttt l ii n nnn eeee
o o u u t l i nn n e e
o o u u t l i n n eeeeee
o o u u t l i n n e
o o u uu t t l i n n e e
oooo uuu u tt lll iii n n eeee
r rrr oooo ssss eeee
rr r o o s s e e
r o o ss eeeeee
r o o ss e
r o o s s e e
r oooo ssss eeee
Job: outline
Date: Sun Sep 17 11:04:58 1995</programlisting>
<para>LPD appends a form feed after this text so the job starts on a
new page (unless you have <literal>sf</literal> (suppress form
feeds) in the destination printer's entry in
<filename>/etc/printcap</filename>).</para>
<para>If you prefer, LPD can make a <emphasis>short header</emphasis>;
specify <literal>sb</literal> (short banner) in the
<filename>/etc/printcap</filename> file. The header page will look
like this:</para>
<programlisting>
rose:kelly Job: outline Date: Sun Sep 17 11:07:51 1995</programlisting>
<para>Also by default, LPD prints the header page first, then the job.
To reverse that, specify <literal>hl</literal> (header last) in
<filename>/etc/printcap</filename>.</para>
</sect3>
<sect3 id="printing-advanced-header-pages-accounting">
<title>Accounting for Header Pages</title>
<para>Using LPD's built-in header pages enforces a particular paradigm
when it comes to printer accounting: header pages must be
<emphasis>free of charge</emphasis>.</para>
<para>Why?</para>
<para>Because the output filter is the only external program that will
have control when the header page is printed that could do
accounting, and it is not provided with any <emphasis>user or
host</emphasis> information or an accounting file, so it has no
idea whom to charge for printer use. It is also not enough to just
<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 LPD does not pass any knowledge
of the <option>-h</option> option to any of the filters.</para>
<para>So, what are your options?</para>
<para>You can:</para>
<itemizedlist>
<listitem>
<para>Accept LPD's paradigm and make header pages free.</para>
</listitem>
<listitem>
<para>Install an alternative to LPD, such as LPRng or PLP. Section
<link linkend="printing-lpd-alternatives">Alternatives to the
Standard Spooler</link> tells more about other spooling
software you can substitute for LPD.</para>
</listitem>
<listitem>
<para>Write a <emphasis>smart</emphasis> output filter. Normally,
an output filter is not meant to do anything more than
initialize a printer or do some simple character conversion. It
is suited for header pages and plain text jobs (when there is no
text (input) filter). But, if there is a text filter for the
plain text jobs, then LPD will start the output filter only for
the header pages. And the output filter can parse the header
page text that LPD generates to determine what user and host to
charge for the header page. The only other problem with this
method is that the output filter still does not know what
accounting file to use (it is not passed the name of the file
from the <literal>af</literal> capability), but if you have a
well-known accounting file, you can hard-code that into the
output filter. To facilitate the parsing step, use the
<literal>sh</literal> (short header) capability in
<filename>/etc/printcap</filename>. Then again, all that might
be too much trouble, and users will certainly appreciate the
more generous system administrator who makes header pages
free.</para>
</listitem>
</itemizedlist>
</sect3>
<sect3 id="printing-advanced-header-pages-ps">
<title>Header Pages on PostScript Printers</title>
<para>As described above, LPD can generate a plain text header page
suitable for many printers. Of course, PostScript cannot directly
print plain text, so the header page feature of LPD is
useless—or mostly so.</para>
<para>One obvious way to get header pages is to have every conversion
filter and the text filter generate the header page. The filters
should should use the user and host arguments to generate a suitable
header page. The drawback of this method is that users will always
get a header page, even if they submit jobs with <command>lpr
-h</command>.</para>
<para>Let us explore this method. The following script takes three
arguments (user login name, host name, and job name) and makes a
simple PostScript header page:</para>
<programlisting>
#!/bin/sh
#
# make-ps-header - make a PostScript header page on stdout
# Installed in /usr/local/libexec/make-ps-header
#
#
# These are PostScript units (72 to the inch). Modify for A4 or
# whatever size paper you are using:
#
page_width=612
page_height=792
border=72
#
# Check arguments
#
if [ $# -ne 3 ]; then
echo "Usage: `basename $0` <user> <host> <job>" 1>&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 <<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>&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 $0` wrong." 1>&2
exit 2
;;
esac
done
[ "$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 LPD will
not generate a header page, and neither will your output filter.
Otherwise, your output filter will read the text from LPD and send
the appropriate header page PostScript code to the printer.</para>
<para>If you have a PostScript printer on a serial line, you can make
use of <command>lprps</command>, which comes with an output filter,
<command>psof</command>, which does the above. Note that
<command>psof</command> does not charge for header pages.</para>
</sect3>
</sect2>
<sect2 id="printing-advanced-network-printers">
<title>Networked Printing</title>
<para>FreeBSD supports networked printing: sending jobs to remote
printers. Networked printing generally refers to two different
things:</para>
<itemizedlist>
<listitem>
<para>Accessing a printer attached to a remote host. You install a
printer that has a conventional serial or parallel interface on
one host. Then, you set up LPD to enable access to the printer
from other hosts on the network. Section <link
linkend="printing-advanced-network-rm">Printers Installed on
Remote Hosts</link> tells how to do this.</para>
</listitem>
<listitem>
<para>Accessing a printer attached directly to a network. The
printer has a network interface in addition (or in place of) a
more conventional serial or parallel interface. Such a printer
might work as follows:</para>
<itemizedlist>
<listitem>
<para>It might understand the LPD protocol and can even queue
jobs from remote hosts. In this case, it acts just like a
regular host running LPD. Follow the same procedure in
section <link linkend="printing-advanced-network-rm">Printers
Installed on Remote Hosts</link> to set up such a
printer.</para>
</listitem>
<listitem>
<para>It might support a data stream network connection. In this
case, you <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 LPD spooling system has built-in support for sending jobs to
other hosts also running LPD (or are compatible with LPD). This
feature enables you to install a printer on one host and make it
accessible from other hosts. It also works with printers that have
network interfaces that understand the LPD protocol.</para>
<para>To enable this kind of remote printing, first install a printer
on one host, the <emphasis>printer host</emphasis>, using the simple
printer setup described in <link linkend="printing-simple">Simple
Printer Setup</link>. Do any advanced setup in <link
linkend="printing-advanced">Advanced Printer Setup</link> that you
need. Make sure to test the printer and see if it works with the
features of LPD you have enabled. Also ensure that the
<emphasis>local host</emphasis> has authorization to use the LPD
service in the <emphasis>remote host</emphasis> (see <link
linkend="printing-advanced-restricting-remote">Restricting Jobs
from Remote Printers</link>).</para>
<para>If you are using a printer with a network interface that is
compatible with LPD, then the <emphasis>printer host</emphasis> in
the discussion below is the printer itself, and the
<emphasis>printer name</emphasis> is the name you configured for the
printer. See the documentation that accompanied your printer and/or
printer-network interface.</para>
<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. LPD will store jobs here
before they get sent to the printer host.</para>
</listitem>
<listitem>
<para>Place the name of the printer host in the
<literal>rm</literal> capability.</para>
</listitem>
<listitem>
<para>Place the printer name on the <emphasis>printer
host</emphasis> in the <literal>rp</literal>
capability.</para>
</listitem>
</orderedlist>
<para>That is it. You do not need to list conversion filters, page
dimensions, or anything else in the
<filename>/etc/printcap</filename> file.</para>
<para>Here is an example. The host <hostid>rose</hostid> has two
printers, <literal>bamboo</literal> and <literal>rattan</literal>.
We will enable users on the host orchid to print to those printers.
Here is the <filename>/etc/printcap</filename> file for
<hostid>orchid</hostid> (back from section <link
linkend="printing-advanced-header-pages-enabling">Enabling Header
Pages</link>). It already had the entry for the printer
<literal>teak</literal>; we have added entries for the two printers
on the host rose:</para>
<programlisting>
#
# /etc/printcap for host orchid - added (remote) printers on rose
#
#
# teak is local; it is connected directly to orchid:
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:\
:if=/usr/local/libexec/ifhp:\
:vf=/usr/local/libexec/vfhp:\
:of=/usr/local/libexec/ofhp:
#
# rattan is connected to rose; send jobs for rattan to rose:
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:lp=:rm=rose:rp=rattan:sd=/var/spool/lpd/rattan:
#
# bamboo is connected to rose as well:
#
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:lp=:rm=rose:rp=bamboo:sd=/var/spool/lpd/bamboo:</programlisting>
<para>Then, we just need to make spooling directories on
<hostid>orchid</hostid>:</para>
<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 orchid typed
<screen>&prompt.user; <userinput>lpr -P bamboo -d sushi-review.dvi</userinput></screen>
the LPD system on orchid would copy the job to the spooling
directory <filename>/var/spool/lpd/bamboo</filename> and note that
it was a DVI job. As soon as the host rose has room in its
<hostid>bamboo</hostid> spooling directory, the two LPDs would
transfer the file to rose. The file would wait in rose's queue
until it was finally printed. It would be converted from DVI to
PostScript (since bamboo is a PostScript printer) on rose.</para>
</sect3>
<sect3 id="printing-advanced-network-net-if">
<title>Printers with Networked Data Stream Interfaces</title>
<para>Often, when you buy a network interface card for a printer, you
can get two versions: one which emulates a spooler (the more
expensive version), or one which just lets you send data to it as if
you were using a serial or parallel port (the cheaper version).
This section tells how to use the cheaper version. For the more
expensive one, see the previous section <link
linkend="printing-advanced-network-rm">Printers Installed on
Remote Hosts</link>.</para>
<para>The format of the <filename>/etc/printcap</filename> file lets
you specify what serial or parallel interface to use, and (if you
are using a serial interface), what baud rate, whether to use flow
control, delays for tabs, conversion of newlines, and more. But
there is no way to specify a connection to a printer that is
listening on a TCP/IP or other network port.</para>
<para>To send data to a networked printer, you need to develop a
communications program that can be called by the text and conversion
filters. Here is one such example: the script
<command>netprint</command> takes all data on standard input and
sends it to a network-attached printer. We specify the hostname of
the printer as the first argument and the port number to which to
connect as the second argument to <command>netprint</command>. Note
that this supports one-way communication only (FreeBSD to printer);
many network printers support two-way communication, and you might
want to take advantage of that (to get printer status, perform
accounting, etc.).</para>
<programlisting>
#!/usr/bin/perl
#
# netprint - Text filter for printer attached to network
# Installed in /usr/local/libexec/netprint
#
$#ARGV eq 1 || die "Usage: $0 <printer-hostname> <port-number>";
$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', &AF_INET, $printer_port, $address);
socket(PRINTER, &PF_INET, &SOCK_STREAM, $protocol)
|| die "Can't create TCP/IP stream socket: $!";
connect(PRINTER, $sockaddr) || die "Can't contact $printer_host: $!";
while (<STDIN>) { print PRINTER; }
exit 0;</programlisting>
<para>We can then use this script in various filters. Suppose we had
a Diablo 750-N line printer connected to the network. The printer
accepts data to print on port number 5100. The host name of the
printer is scrivener. Here is the text filter for the
printer:</para>
<programlisting>
#!/bin/sh
#
# diablo-if-net - Text filter for Diablo printer `scrivener' listening
# on port 5100. Installed in /usr/local/libexec/diablo-if-net
#
exec /usr/libexec/lpr/lpf "$@" | /usr/local/libexec/netprint scrivener 5100</programlisting>
</sect3>
</sect2>
<sect2 id="printing-advanced-restricting">
<title>Restricting Printer Usage</title>
<para>This section gives information on restricting printer usage. The
LPD system lets you control who can access a printer, both locally or
remotely, whether they can print multiple copies, how large their jobs
can be, and how large the printer queues can get.</para>
<sect3 id="printing-advanced-restricting-copies">
<title>Restricting Multiple Copies</title>
<para>The LPD system makes it easy for users to print multiple copies
of a file. Users can print jobs with <command>lpr -#5</command>
(for example) and get five copies of each file in the job. Whether
this is a good thing is up to you.</para>
<para>If you feel multiple copies cause unnecessary wear and tear on
your printers, you can disable the <option>-#</option> option to
&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>'s a bit more delicate, so we will
disable multiple copies by adding the <literal>sc</literal>
capability:</para>
<programlisting>
#
# /etc/printcap for host rose - restrict multiple copies on bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:\
:if=/usr/local/libexec/if-simple:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:sc:\
:lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:</programlisting>
<para>Now, we also need to add the <literal>sc</literal> capability on
the host <hostid>orchid</hostid>'s
<filename>/etc/printcap</filename> (and while we are at it, let us
disable multiple copies for the printer
<literal>teak</literal>):</para>
<programlisting>
#
# /etc/printcap for host orchid - no multiple copies for local
# printer teak or remote printer bamboo
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sd=/var/spool/lpd/teak:mx#0:sc:\
:if=/usr/local/libexec/ifhp:\
:vf=/usr/local/libexec/vfhp:\
:of=/usr/local/libexec/ofhp:
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:lp=:rm=rose:rp=rattan:sd=/var/spool/lpd/rattan:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:lp=:rm=rose:rp=bamboo:sd=/var/spool/lpd/bamboo:sc:</programlisting>
<para>By using the <literal>sc</literal> capability, we prevent the
use of <command>lpr -#</command>, but that still does not prevent
users from running &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 root) will be greeted with
<errorname>lpr: Not a member of the restricted group</errorname>
if they try to print to the controlled printer.</para>
<para>As with the <literal>sc</literal> (suppress multiple copies)
capability, you need to specify <literal>rg</literal> on remote
hosts that also have access to your printers, if you feel it is
appropriate (see section <link
linkend="printing-advanced-network-rm">Printers Installed on
Remote Hosts</link>).</para>
<para>For example, we will let anyone access the printer
<literal>rattan</literal>, but only those in group
<literal>artists</literal> can use <literal>bamboo</literal>. Here
is the familiar <filename>/etc/printcap</filename> for host
<hostid>rose</hostid>:</para>
<programlisting>
#
# /etc/printcap for host rose - restricted group for bamboo
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:\
:if=/usr/local/libexec/if-simple:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:\
:lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:</programlisting>
<para>Let us leave the other example
<filename>/etc/printcap</filename> file (for the host
<hostid>orchid</hostid>) alone. Of course, anyone on
<hostid>orchid</hostid> can print to <literal>bamboo</literal>. It
might be the case that we only allow certain logins on
<hostid>orchid</hostid> anyway, and want them to have access to the
printer. Or not.</para>
<note>
<para>There can be only one restricted group per printer.</para>
</note>
</sect3>
<sect3 id="printing-advanced-restricting-sizes">
<title>Controlling Sizes of Jobs Submitted</title>
<para>If you have many users accessing the printers, you probably need
to put an upper limit on the sizes of the files users can submit to
print. After all, there is only so much free space on the
filesystem that houses the spooling directories, and you also need
to make sure there is room for the jobs of other users.</para>
<para>LPD enables you to limit the maximum byte size a file in a job
can be with the <literal>mx</literal> capability. The units are in
BUFSIZ blocks, which are 1024 bytes. If you put a zero for this
capability, there will be no limit on file size; 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>LPD will not refuse a file that is larger than the limit you
place on a printer. Instead, it will queue as much of the file up
to the limit, which will then get printed. The rest will be
discarded. Whether this is correct behavior is up for
debate.</para>
<para>Let us add limits to our example printers
<literal>rattan</literal> and <literal>bamboo</literal>. Since
those artists' PostScript files tend to be large, we will limit them
to five megabytes. We will put no limit on the plain text line
printer:</para>
<programlisting>
#
# /etc/printcap for host rose
#
#
# No limit on job size:
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh: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:fs#0x82000e1:xs#0x820:rw:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:</programlisting>
<para>Again, the limits apply to the local users only. If you have
set up access to your printers remotely, remote users will not get
those limits. You will need to specify the <literal>mx</literal>
capability in the remote <filename>/etc/printcap</filename> files as
well. See section <link
linkend="printing-advanced-network-rm">Printers Installed on
Remote Hosts</link> for more information on remote
printing.</para>
<para>There is another specialized way to limit job sizes from remote
printers; see section <link
linkend="printing-advanced-restricting-remote">Restricting Jobs
from Remote Printers</link>.</para>
</sect3>
<sect3 id="printing-advanced-restricting-remote">
<title>Restricting Jobs from Remote Printers</title>
<para>The LPD spooling system provides several ways to restrict print
jobs submitted from remote hosts:</para>
<variablelist>
<varlistentry>
<term>Host restrictions</term>
<listitem>
<para>You can control from which remote hosts a local LPD
accepts requests with the files
<filename>/etc/hosts.equiv</filename> and
<filename>/etc/hosts.lpd</filename>. LPD checks to see if an
incoming request is from a host listed in either one of these
files. If not, LPD refuses the request.</para>
<para>The format of these files is simple: one host name per
line. Note that the file
<filename>/etc/hosts.equiv</filename> is also used by the
&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 LPD, LPD
will refuse them.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Size restrictions</term>
<listitem>
<para>You can control how much free space there needs to remain
on the filesystem where a spooling directory resides. Make a
file called <filename>minfree</filename> in the spooling
directory for the local printer. Insert in that file a number
representing how many disk blocks (512 bytes) of free space
there has to be for a remote job to be accepted.</para>
<para>This lets you insure that remote users will not fill your
filesystem. You can also use it to give a certain priority to
local users: they will be able to queue jobs long after the
free disk space has fallen below the amount specified in the
<filename>minfree</filename> file.</para>
<para>For example, let us add a <filename>minfree</filename>
file for the printer <hostid>bamboo</hostid>. We examine
<filename>/etc/printcap</filename> to find the spooling
directory for this printer; here is <hostid>bamboo</hostid>'s
entry:</para>
<programlisting>
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:mx#5000:\
:lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:mx#5000:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:</programlisting>
<para>The spooling directory is the given in the
<literal>sd</literal> capability. We will make three
megabytes (which is 6144 disk blocks) the amount of free disk
space that must exist on the filesystem for LPD to accept
remote jobs:</para>
<screen>&prompt.root; <userinput>echo 6144 > /var/spool/lpd/bam
boo/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, LPD will accept jobs from remote
hosts <emphasis>if</emphasis> the user submitting the job also
has an account of the same login name on the local host.
Otherwise, LPD refuses the job.</para>
<para>This capability is particularly useful in an environment
where there are (for example) different departments sharing a
network, and some users transcend departmental boundaries. By
giving them accounts on your systems, they can use your
printers from their own departmental systems. If you would
rather allow them to use <emphasis>only</emphasis> your
printers and not your compute resources, you can give them
<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>
<para>So, you need to charge for printouts. And why not? Paper and ink
cost money. And then there are maintenance costs—printers are
loaded with moving parts and tend to break down. You have examined
your printers, usage patterns, and maintenance fees and have come up
with a per-page (or per-foot, per-meter, or per-whatever) cost. Now,
how do you actually start accounting for printouts?</para>
<para>Well, the bad news is the LPD spooling system does not provide
much help in this department. Accounting is highly dependent on the
kind of printer in use, the formats being printed, and
<emphasis>your</emphasis> requirements in charging for printer
usage.</para>
<para>To implement accounting, you have to modify a printer's text
filter (to charge for plain text jobs) and the conversion filters (to
charge for other file formats), to count pages or query the printer
for pages printed. You cannot get away with using the simple output
filter, since it cannot do accounting. See section <link
linkend="printing-advanced-filter-intro">Filters</link>.</para>
<para>Generally, there are two ways to do accounting:</para>
<itemizedlist>
<listitem>
<para><emphasis>Periodic accounting</emphasis> is the more common
way, possibly because it is easier. Whenever someone prints a
job, the filter logs the user, host, and number of pages to an
accounting file. Every month, semester, year, or whatever time
period you prefer, you collect the accounting files for the
various printers, tally up the pages printed by users, and charge
for usage. Then you truncate all the logging files, starting with
a clean slate for the next period.</para>
</listitem>
<listitem>
<para><emphasis>Timely accounting</emphasis> is less common,
probably because it is more difficult. This method has the
filters charge users for printouts as soon as they use the
printers. Like disk quotas, the accounting is immediate. You can
prevent users from printing when their account goes in the red,
and might provide a way for users to check and adjust their
<quote>print quotas.</quote> But this method requires some database
code to track users and their quotas.</para>
</listitem>
</itemizedlist>
<para>The LPD spooling system supports both methods easily: since you
have to provide the filters (well, most of the time), you also have to
provide the accounting code. But there is a bright side: you have
enormous flexibility in your accounting methods. For example, you
choose whether to use periodic or timely accounting. You choose what
information to log: user names, host names, job types, pages printed,
square footage of paper used, how long the job took to print, and so
forth. And you do so by modifying the filters to save this
information.</para>
<sect3>
<title>Quick and Dirty Printer Accounting</title>
<para>FreeBSD comes with two programs that can get you set up with
simple periodic accounting right away. They are the text filter
<command>lpf</command>, described in section <link
linkend="printing-advanced-lpf">lpf: a Text Filter</link>, and
&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>), LPD starts
the text and the conversion filters with the name of the accounting
file to use on the filter command line. The filters can use this
argument to know where to write an accounting file entry. The name
of this file comes from the <literal>af</literal> capability in
<filename>/etc/printcap</filename>, and if not specified as an
absolute path, is relative to the spooling directory.</para>
<para>LPD starts <command>lpf</command> with page width and length
arguments (from the <literal>pw</literal> and <literal>pl</literal>
capabilities). <command>lpf</command> uses these arguments to
determine how much paper will be used. After sending the file to
the printer, it then writes an accounting entry in the accounting
file. The entries look like this:</para>
<programlisting>
2.00 rose:andy
3.00 rose:kelly
3.00 orchid:mary
5.00 orchid:mary
2.00 orchid:zhang</programlisting>
<para>You should use a separate accounting file for each printer, as
<command>lpf</command> has no file locking logic built into it, and
two <command>lpf</command>s might corrupt each other's entries if
they were to write to the same file at the same time. A easy way to
insure a separate accounting file for each printer is to use
<literal>af=acct</literal> in <filename>/etc/printcap</filename>.
Then, each accounting file will be in the spooling directory for a
printer, in a file named <filename>acct</filename>.</para>
<para>When you are ready to charge users for printouts, run the
&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>…</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's not that hard to solve: you
count how many lines are in a job and compare it to how many lines
per page your printer supports. Do not forget to take into account
backspaces in the file which overprint lines, or long logical lines
that wrap onto one or more additional physical lines.</para>
<para>The text filter <command>lpf</command> (introduced in <link
linkend="printing-advanced-lpf">lpf: a Text Filter</link>) takes
into account these things when it does accounting. If you are
writing a text filter which needs to do accounting, you might want
to examine <command>lpf</command>'s source code.</para>
<para>How do you handle other file formats, though?</para>
<para>Well, for DVI-to-LaserJet or DVI-to-PostScript conversion, you
can have your filter parse the diagnostic output of
<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—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>
<para>This section tells you how to use printers you have setup with
FreeBSD. Here is an overview of the user-level commands:</para>
<variablelist>
<varlistentry>
<term>&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">Administrating the LPD
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>
<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>
<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 LPD spooling system. Each printer has a queue of jobs, and
your job waits in that queue along with other jobs from yourself and
from other users. The printer prints those jobs in a first-come,
first-served order.</para>
<para>To display the queue for the default printer, type &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 <hostid>bamboo</hostid>. 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 files she's 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 LPD
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 <hostid>bamboo</hostid>:</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>
<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</para>
<para>&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 LPD spooler.
Because we used the <option>-t</option> option to</para>
<para>&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 LPD to handle the job
specially:</para>
<variablelist>
<varlistentry>
<term>-# <replaceable>copies</replaceable></term>
<listitem>
<para>Produce a number of <replaceable>copies</replaceable> of
each file in the job instead of just one copy. An
administrator may disable this option to reduce printer
wear-and-tear and encourage photocopier usage. See section
<link
linkend="printing-advanced-restricting-copies">Restricting
Multiple Copies</link>.</para>
<para>This example prints three copies of
<filename>parser.c</filename> followed by three copies of
<filename>parser.h</filename> to the default printer:</para>
<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 LPD system will send mail to your account when it
finishes handling your job. In its message, it will tell you
if the job completed successfully or if there was an error,
and (often) what the error was.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>-s</term>
<listitem>
<para>Do not copy the files to the spooling directory, but make
symbolic links to them instead.</para>
<para>If you are printing a large job, you probably want to use
this option. It saves space in the spooling directory (your
job might overflow the free space on the filesystem where the
spooling directory resides). It saves time as well since LPD
will not have to copy each and every byte of your job to the
spooling directory.</para>
<para>There is a drawback, though: since LPD will refer to the
original files directly, you cannot modify or remove them
until they have been printed.</para>
<note>
<para>If you are printing to a remote printer, LPD will
eventually have to copy files from the local host to the
remote host, so the <option>-s</option> option will save
space only on the local spooling directory, not the remote.
It is still useful, though.</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term>-r</term>
<listitem>
<para>Remove the files in the job after copying them to the
spooling directory, or after printing them with the
<option>-s</option> option. Be careful with this
option!</para>
</listitem>
</varlistentry>
</variablelist>
</sect3>
<sect3 id="printing-lpr-options-misc">
<title>Header Page Options</title>
<para>These options to &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>Administrating 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 root)
can submit jobs for the printer. An <emphasis>enabled</emphasis>
queue allows jobs to be submitted. A printer can be
<emphasis>started</emphasis> for a disabled queue, in which case it
will continue to print jobs in the queue until the queue is
empty.</para>
<para>In general, you have to have root privileges to use the
&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 takes a <replaceable>printer-name</replaceable> argument to
tell on which printer to operate. You can use <literal>all</literal>
for the <replaceable>printer-name</replaceable> to mean all printers
listed in <filename>/etc/printcap</filename>.</para>
<variablelist>
<varlistentry>
<term><command>abort
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Cancel the current job and stop the printer. Users can
still submit jobs if the queue's enabled.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>clean
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Remove old files from the printer's spooling directory.
Occasionally, the files that make up a job are not properly
removed by LPD, particularly if there have been errors during
printing or a lot of administrative activity. This command
finds files that do not belong in the spooling directory and
removes them.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>disable
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Disable queuing of new jobs. If the printer's started, it
will continue to print any jobs remaining in the queue. The
superuser (root) can always submit jobs, even to a disabled
queue.</para>
<para>This command is useful while you are testing a new printer
or filter installation: disable the queue and submit jobs as
root. Other users will not be able to submit jobs until you
complete your testing and re-enable the queue with the
<command>enable</command> command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>down <replaceable>printer-name</replaceable>
<replaceable>message</replaceable></command></term>
<listitem>
<para>Take a printer down. Equivalent to
<command>disable</command> followed by <command>stop</command>.
The <replaceable>message</replaceable> appears as the printer's
status whenever a user checks the printer's queue with
&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 LPD, but they cannot start
a printer stopped with either the <command>stop</command> or
<command>down</command> commands. The
<command>restart</command> command is equivalent to
<command>abort</command> followed by
<command>start</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>start
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Start the printer. The printer will print jobs in its
queue.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>stop
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Stop the printer. The printer will finish the current job
and will not print anything else in its queue. Even though the
printer is stopped, users can still submit jobs to an enabled
queue.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>topq <replaceable>printer-name</replaceable>
<replaceable>job-or-username</replaceable></command></term>
<listitem>
<para>Rearrange the queue for
<replaceable>printer-name</replaceable> by placing the jobs with
the listed <replaceable>job</replaceable> numbers or the jobs
belonging to <replaceable>username</replaceable> at the top of
the queue. For this command, you cannot use
<literal>all</literal> as the
<replaceable>printer-name</replaceable>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>up
<replaceable>printer-name</replaceable></command></term>
<listitem>
<para>Bring a printer up; the opposite of the
<command>down</command> command. Equivalent to
<command>start</command> followed by
<command>enable</command>.</para>
</listitem>
</varlistentry>
</variablelist>
<para>&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 LPD
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>
<para>Unfortunately, I have located only <emphasis>two</emphasis>
alternatives—and they are almost identical to each other! They
are:</para>
<variablelist>
<varlistentry>
<term>PLP, the Portable Line Printer Spooler System</term>
<listitem>
<para>PLP was based on software developed by Patrick Powell and then
maintained by an Internet-wide group of developers. The main site
for the software is at <ulink
url="ftp://ftp.iona.ie/pub/plp/">ftp://ftp.iona.ie/pub/plp/</ulink>.
There is also a <ulink
url="http://www.iona.ie:8000/www/hyplan/jmason/plp.html">web
page</ulink>.</para>
<para>It is quite similar to the BSD LPD spooler, but boasts a
host of features, including:</para>
<itemizedlist>
<listitem>
<para>Better network support, including built-in support for
networked printers, NIS-maintained printcaps, and NFS-mounted
spooling directories</para>
</listitem>
<listitem>
<para>Sophisticated queue management, allowing multiple printers
on a queue, transfer of jobs between queues, and queue
redirection</para>
</listitem>
<listitem>
<para>Remote printer control functions</para>
</listitem>
<listitem>
<para>Prioritization of jobs</para>
</listitem>
<listitem>
<para>Expansive security and access options</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>LPRng</term>
<listitem>
<para>LPRng, which purportedly means <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 LPRng. The main site for LPRng is <ulink
url="ftp://dickory.sdsu.edu/pub/LPRng/">ftp://dickory.sdsu.edu/pub/LPRng/</ulink>.</para>
</listitem>
</varlistentry>
</variablelist>
</sect1>
<sect1 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 && printf "\f" && 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>
!"#$%&'()*+,-./01234
"#$%&'()*+,-./012345
#$%&'()*+,-./0123456</programlisting>
<para>You have become another victim of the <emphasis>staircase
effect</emphasis>, caused by conflicting interpretations of
what characters should indicate a new line. UNIX-style
operating systems use a single character: ASCII code 10, the
line feed (LF). MS-DOS, OS/2, and others uses a pair of
characters, ASCII code 10 <emphasis>and</emphasis> ASCII code
13 (the carriage return or CR). Many printers use the MS-DOS
convention for representing new-lines.</para>
<para>When you print with FreeBSD, your text used just the line
feed character. The printer, upon seeing a line feed
character, advanced the paper one line, but maintained the
same horizontal position on the page for the next character
to print. That is what the carriage return is for: to move
the location of the next character to print to the left edge
of the paper.</para>
<para>Here is what FreeBSD wants your printer to do:</para>
<informaltable frame="none">
<tgroup cols="2">
<tbody>
<row>
<entry>Printer received CR</entry>
<entry>Printer prints CR</entry>
</row>
<row>
<entry>Printer received LF</entry>
<entry>Printer prints CR + LF</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>Here are some ways to achieve this:</para>
<itemizedlist>
<listitem>
<para>Use the printer's configuration switches or control
panel to alter its interpretation of these characters.
Check your printer's manual to find out how to do
this.</para>
<note>
<para>If you boot your system into other operating systems
besides FreeBSD, you may have to
<emphasis>reconfigure</emphasis> the printer to use a an
interpretation for CR and LF characters that those other
operating systems use. You might prefer one of the other
solutions, below.</para>
</note>
</listitem>
<listitem>
<para>Have FreeBSD's serial line driver automatically
convert LF to CR+LF. Of course, this works with printers
on serial ports <emphasis>only</emphasis>. To enable this
feature, set the CRMOD bit in <literal>fs</literal>
capability in the <filename>/etc/printcap</filename> file
for the printer.</para>
</listitem>
<listitem>
<para>Send an <emphasis>escape code</emphasis> to the
printer to have it temporarily treat LF characters
differently. Consult your printer's manual for escape
codes that your printer might support. When you find the
proper escape code, modify the text filter to send the
code first, then send the print job.</para>
<para>Here is an example text filter for printers that
understand the Hewlett-Packard PCL escape codes. This
filter makes the printer treat LF characters as a LF and
CR; then it sends the job; then it sends a form feed to
eject the last page of the job. It should work with
nearly all Hewlett Packard printers.</para>
<programlisting>
#!/bin/sh
#
# hpif - Simple text input filter for lpd for HP-PCL based printers
# Installed in /usr/local/libexec/hpif
#
# Simply copies stdin to stdout. Ignores all filter arguments.
# Tells printer to treat LF as CR+LF. Ejects the page when done.
printf "\033&k2G" && cat && printf "\033&l0H" && exit 0
exit 2</programlisting>
<para>Here is an example <filename>/etc/printcap</filename>
from a host called orchid. It has a single printer
attached to its first parallel port, a Hewlett Packard
LaserJet 3Si named <hostid>teak</hostid>. It is using the
above script as its text filter:</para>
<programlisting>
#
# /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sh:sd=/var/spool/lpd/teak:mx#0:\
:if=/usr/local/libexec/hpif:</programlisting>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>It overprinted each line.</term>
<listitem>
<para>The printer never advanced a line. All of the lines of
text were printed on top of each other on one line.</para>
<para>This problem is the <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 TANDEM bit in the
<literal>fs</literal> capability.</para>
</listitem>
<listitem>
<para>If the printer supports carrier flow control, specify
the MDMBUF bit in the <literal>fs</literal> capability.
Make sure the cable connecting the printer to the computer
is correctly wired for carrier flow control.</para>
</listitem>
<listitem>
<para>If the printer does not support any flow control, use
some combination of the NLDELAY, TBDELAY, CRDELAY, VTDELAY,
and BSDELAY bits in the <literal>fs</literal> capability
to add appropriate delays to the stream of data sent to
the printer.</para>
</listitem>
</itemizedlist>
</listitem>
</varlistentry>
<varlistentry>
<term>It printed garbage.</term>
<listitem>
<para>The printer printed what appeared to be random garbage,
but not the desired text.</para>
<para>This is usually another symptom of incorrect
communications parameters with a serial printer. Double-check
the bps rate in the <literal>br</literal> capability, and the
parity bits in the <literal>fs</literal> and
<literal>fc</literal> capabilities; make sure the printer is
using the same settings as specified in the
<filename>/etc/printcap</filename> file.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Nothing happened.</term>
<listitem>
<para>If nothing happened, the problem is probably within
FreeBSD and not the hardware. Add the log file
(<literal>lf</literal>) capability to the entry for the
printer you are debugging in the
<filename>/etc/printcap</filename> file. For example, here is
the entry for <literal>rattan</literal>, with the
<literal>lf</literal> capability:</para>
<programlisting>
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:\
:if=/usr/local/libexec/if-simple:\
:lf=/var/log/rattan.log</programlisting>
<para>Then, try printing again. Check the log file (in our
example, <filename>/var/log/rattan.log</filename>) to see any
error messages that might appear. Based on the messages you
see, try to correct the problem.</para>
<para>If you do not specify a <literal>lf</literal> capability,
LPD uses <filename>/dev/console</filename> as a
default.</para>
</listitem>
</varlistentry>
</variablelist>
</sect1>
</chapter>
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