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<!-- This is an SGML document in the linuxdoc DTD describing
Printing with FreeBSD. By Sean Kelly, 1995.
$Id: printing.sgml,v 1.5 1996/01/31 19:03:00 mpp Exp $
The FreeBSD Documentation Project
<!DOCTYPE linuxdoc PUBLIC "-//FreeBSD//DTD linuxdoc//EN">
<article>
<title> Printing with FreeBSD
<author> Sean Kelly <tt/kelly@fsl.noaa.gov/
<date> 30 September 1995, (c) 1995
<abstract> This document describes printing with FreeBSD. It
tells how to set up printer hardware, how to configure FreeBSD
to use printers, and how to control the print queue and print
a variety of file formats. </abstract>
<toc>
-->
<chapt><heading>Printing<label id="printing"></heading>
<p><em>Contributed by &a.kelly;<newline>30 September 1995</em>
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 iss the
standard printer control system in FreeBSD. This section
introduces the LPD spooling system, often simply called LPD.
If you are already familiar with LPD or another printer
spooling system, you may wish to skip to section <ref
id="printing:intro:setup" name="Setting up the spooling
system">.
<sect><heading>What the Spooler Does<label
id="printing:intro:spooler"></heading>
<p> LPD controls everything about a host's printers. It is
responsible for a number of things:
<itemize>
<item>It controls access to attached printers and
printers attached to other hosts on the network.
<item>It enables users to submit files to be printed;
these submissions are known as <em/jobs/.
<item>It prevents multiple users from accessing a printer
at the same time by maintaining a <em/queue/ for each
printer.
<item>It can print <em/header pages/ (also known as
<em/banner/ or <em/burst/ pages) so users can easily
find jobs they have printed in a stack of printouts.
<item>It takes care of communications parameters for
printers connected on serial ports.
<item>It can send jobs over the network to another LPD
spooler on another host.
<item>It can run special filters to format jobs to be
printed for various printer languages or printer
capabilities.
<item>It can account for printer usage.
</itemize>
Through a configuration file, and by providing the special
filter programs, you can enable the LPD system to do all or
some subset of the above for a great variety of printer
hardware.
<sect><heading>Why You Should Use the Spooler<label
id="printing:intro:why"></heading>
<p> If you are the sole user of your system, you may be
wondering why you should bother with the spooler when you
don't need access control, header pages, or printer
accounting. While it's possible to enable direct access to
a printer, you should use the spooler anyway since
<itemize>
<item>LPD prints jobs in the background; you don't have
to wait for data to be copied to the printer.
<item>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.
<item>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.
</itemize>
<sect><heading>Setting Up the Spooling System<label
id="printing:intro:setup"></heading>
<p> 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:
<itemize>
<item>See section <ref name="Simple Printer Setup"
id="printing:simple"> to learn how to connect a
printer, tell LPD how to communicate with it, and
print plain text files to the printer.
<item>See section <ref name="Advanced Printer Setup"
id="printing:advanced"> 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.
</itemize>
<sect><heading>Simple Printer Setup<label
id="printing:simple"></heading>
<p> This section tells how to configure printer hardware and the
LPD software to use the printer. It teaches the basics:
<itemize>
<item>Section <ref id="printing:hardware" name="Hardware
Setup"> gives some hints on connecting the printer to a
port on your computer.
<item>Section <ref id="printing:software" name="Software
Setup"> shows how to setup the LPD spooler configuration
file <tt>/etc/printcap</tt>.
</itemize>
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 <ref id="printing:advanced:network:net-if" name="Printers
With Networked Data Stream Interaces">.
Although this section is called ``Simple Printer Setup,'' 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.
<sect1><heading>Hardware Setup<label id="printing:hardware"></heading>
<p> 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.
If you have already connected your printer and have
successfully printed with it under another operating system,
you can probably skip to section <ref id="printing:software"
name="Software Setup">.
<sect2><heading>Ports and Cables<label
id="printing:ports"></heading>
<p> Nearly all printers you can get for a PC today support
one or both of the following interfaces:
<itemize>
<item><em/Serial/ 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.
<item><em/Parallel/ 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.
<p> Parallel interfaces are sometimes known as
``Centronics'' interfaces, named after the connector
type on the printer.
</itemize>
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.
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.
So, which interface should you use?
<itemize>
<item>If you need two-way communication, use a serial
port. FreeBSD does not yet support two-way
communication over a parallel port.
<item>If you do not need two-way communication and can
pick parallel or serial, prefer the parallel
interface. It keeps a serial port free for other
peripherals---such as a terminal or a modem---and is
faster most of the time. It is also easier to
configure.
<item>Finally, use whatever works.
</itemize>
<sect2><heading>Parallel Ports<label id="printing:parallel"></heading>
<p> 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.
Remember which parallel port you used on the computer. The
first parallel port is /dev/lpt0 to FreeBSD; the second is
/dev/lpt1, and so on.
<sect2><heading>Serial Ports<label id="printing:serial"></heading>
<p> 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.
If you are unsure what the ``proper serial cable'' is, you
may wish to try one of the following alternatives:
<itemize>
<item>A <em/modem/ 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 DTE-to-DCE
cable.
<item>A <em/null-modem/ 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
DTE-to-DTE cable.
<item>A <em/serial printer/ cable, required for some
unusual printers, is like the null modem cable, but
sends some signals to their counterparts instead of
being internally shorted.
</itemize>
You should also set up the communications parameters for
the printer, usually through front-panel controls or DIP
switches on the printer. Choose the highest bps (bits per
second, sometimes <em/baud rate/) 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 <em/in-band/ or <em/software/)
flow control. Remember these settings for the software
configuration that follows.
<sect1><heading>Software Setup<label id="printing:software"></heading>
<p> This section describes the software setup necessary to
print with the LPD spooling system in FreeBSD.
Here is an outline of the steps involved:
<enum>
<item>Configure your kernel, if necessary, for the port
you are using for the printer; section <ref
id="printing:kernel" name="Kernel Configuration"> tells
you what you need to do.
<item>Set the communications mode for the parallel port,
if you are using a parallel port; section <ref
id="printing:parallel-port-mode" name = "Setting the
Communication Mode for the Parallel Port"> gives
details.
<item>Test if the operating system can send data to the
printer. Section <ref id="printing:testing"
name="Checking Printer Communications"> gives some
suggestions on how to do this.
<item>Set up LPD for the printer by modifying the file
<tt>/etc/printcap</tt>. Section <ref
id="printing:printcap" name="The /etc/printcap File">
shows you how.
</enum>
<sect2><heading>Kernel Configuration<label
id="printing:kernel"></heading>
<p> 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.
To find out if the kernel you are currently using supports a serial
interface, type
<tscreen>
<tt>dmesg &verbar; grep sio</tt><it/N/
</tscreen>
where <it/N/ is the number of the serial port, starting
from zero. If you see output similar to the following
<tscreen><verb>
sio2 at 0x3e8-0x3ef irq 5 on isa
sio2: type 16550A
</verb></tscreen>
then the kernel supports the port.
To find out if the kernel supports a parallel interface,
type
<tscreen>
<tt>dmesg &verbar; grep lpt</tt><it/N/
</tscreen>
where <it/N/ is the number of the parallel port, starting
from zero. If you see output similar to the following
<tscreen><verb>
lpt0 at 0x378-0x37f on isa
</verb></tscreen>
then the kernel supports the port.
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.
To add support for a serial port, see the section on
kernel configuration. To add support for a parallel port,
see that section <em/and/ the section that follows.
<sect3><heading>Adding <tt>/dev</tt> Entries for the Ports
<label id="printing:dev-ports"></heading>
<p> 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
<tt>/dev</tt> directory are for.
<bf>To add a <tt>/dev</tt> entry for a port:</bf>
<enum>
<item>Become root with the <tt/su/ command. Enter
the root password when prompted.
<item>Change to the <tt>/dev</tt> directory:
<tscreen><verb>
cd /dev
</verb></tscreen>
<item>Type
<tscreen>
<tt> ./MAKEDEV</tt> <it/port/
</tscreen>
where <it/port/ is the device entry for the port you
want to make. Use <tt/lpt0/ for the first parallel
port, <tt/lpt1/ for the second, and so on; use
<tt/ttyd0/ for the first serial port, <tt/ttyd1/ for
the second, and so on.
<item>Type
<tscreen>
<tt>ls -l</tt> <it/port/
</tscreen>
to make sure the device entry got created.
</enum>
<sect3><heading>Setting the Communication Mode for the Parallel Port
<label id="printing:parallel-port-mode"></heading>
<p> When you are using the parallel interface, you can
choose whether FreeBSD should use interrupt-driven or
polled communication with the printer.
<itemize>
<item>The <em/interrupt-driven/ 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.
<item>The <em/polled/ 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.
</itemize>
The interrupt-driven method is somewhat faster but uses
up a precious IRQ line. You should use whichever one
works.
You can set the communications mode in two ways: by
configuring the kernel or by using the <tt/lptcontrol/
program.
<bf>To set the communications mode by configuring the
kernel:</bf>
<enum>
<item>Edit your kernel configuration file. Look for
or add an <tt/lpt0/ entry. If you are setting up the
second parallel port, use <tt/lpt1/ instead. Use
<tt/lpt2/ for the third port, and so on.
<itemize>
<item>If you want interrupt-driven mode, add the <tt/irq/
specifier:
<tscreen>
<tt>device lpt0 at isa? port? tty irq <it/N/ vector lptintr</tt>
</tscreen>
where <it/N/ is the IRQ number for your
computer's parallel port.
<item>If you want polled mode, do not add the
<tt/irq/ specifier:
<tscreen>
<tt>device lpt0 at isa? port? tty vector lptintr</tt>
</tscreen>
</itemize>
<item>Save the file. Then configure, build, and
install the kernel, then reboot. See <ref id="kernelconfig"
name="kernel configuration"> for more details.
</enum>
<bf>To set the communications mode with
<tt/lptcontrol/:</bf>
<itemize>
<item>
Type
<tscreen>
<tt>lptcontrol -i -u <it/N/</tt>
</tscreen>
to set interrupt-driven mode for <tt/lpt<it/N//.
<item>
Type
<tscreen>
<tt>lptcontrol -p -u <it/N/</tt>
</tscreen>
to set polled-mode for <tt/lpt<it/N//.
</itemize>
You could put these commands in your
<tt>/etc/rc.local</tt> file to set the mode each time
your system boots. See lptcontrol(8) for more
information.
<sect3><heading>Checking Printer Communications<label
id="printing:testing"></heading>
<p> 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.
To test the printer, we will send some text to it. For
printers that can immediately print characters sent to
them, the program <tt/lptest/ is perfect: it generates
all 96 printable ASCII characters in 96 lines.
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:
<code>
%!PS
100 100 moveto 300 300 lineto stroke
310 310 moveto
/Helvetica findfont 12 scalefont setfont
(Is this thing working?) show
showpage
</code>
<em/Note:/ When this document refers to a printer
language, I am assuming a language like PostScript, and
not Hewlett Packard's PCL. Although PCL has great
functionality, you can intermingle plain text with its
escape sequences. PostScript cannot directly print
plain text, and that is the kind of printer language for
which we must make special accommodations.
<sect4><heading>Checking a Parallel Printer<label
id="printing:checking:parallel"></heading>
<p> This section tells you how to check if FreeBSD can
communicate with a printer connected to a parallel port.
<bf>To test a printer on a parallel port:</bf>
<enum>
<item>Become root with <tt/su/.
<item>Send data to the printer.
<itemize>
<item>If the printer can print plain text, then
use <tt/lptest/. Type:
<tscreen>
<tt>lptest > /dev/lpt<it/N/</tt>
</tscreen>
where <it/N/ is the number of the parallel
port, starting from zero.
<item>If the printer understands PostScript or
other printer language, then send a small
program to the printer. Type
<tscreen>
<tt>cat > /dev/lpt<it/N/</tt>
</tscreen>
Then, line by line, type the program
<em/carefully/ as you cannot edit a line once
you have pressed RETURN or ENTER. When you have
finished entering the program, press
CONTROL+D, or whatever your end of file key
is.
<p> Alternatively, you can put the program in
a file and type
<tscreen>
<tt>cat <it/file/ > /dev/lpt<it/N/</tt>
</tscreen>
where <it/file/ is the name of the file
containing the program you want to send to
the printer.
</itemize>
</enum>
You should see something print. Do not worry if the
text doesn't look right; we'll fix such things later.
<sect4><heading>Checking a Serial Printer<label
id="printing:checking:serial"></heading>
<p> This section tells you how to check if FreeBSD can
communicate with a printer on a serial port.
<bf>To test a printer on a serial port:</bf>
<enum>
<item>Become root with <tt/su/.
<item>Edit the file <tt>/etc/remote</tt>. Add the
following entry:
<tscreen>
<tt>printer:dv=/dev/<it/port/:br&num;<it/bps-rate/:pa=<it/parity/</tt>
</tscreen>
where <it/port/ is the device entry for the serial
port (<tt/ttyd0/, <tt/ttyd1/, etc.), <it/bps-rate/
is the bits-per-second rate at which the printer
communicates, and <it/parity/ is the parity
required by the printer (either <tt/even/,
<tt/odd/, <tt/none/, or <tt/zero/).
<p>
Here is a sample entry for a printer connected
via a serial line to the third serial port at
19200 bps with no parity:
<code>
printer:dv=/dev/ttyd2:br#19200:pa=none
</code>
<item>Connect to the printer with <tt/tip/. Type:
<tscreen><verb>
tip printer
</verb></tscreen>
If this step does not work, edit the file
<tt>/etc/remote</tt> again and try using
<tt>/dev/cuaa<it/N/</tt> instead of
<tt>/dev/ttyd<it/N/</tt>.
<item>Send data to the printer.
<itemize>
<item>If the printer can print plain text, then
use <tt/lptest/. Type:
<tscreen><verb>
~$lptest
</verb></tscreen>
<item>If the printer understands PostScript or
other printer language, then send a small
program to the printer. Type the program,
line by line, <em/very carefully/ as
backspacing or other editing keys may be
significant to the printer. You may also need
to type a special end-of-file key for the
printer so it knows it received the whole
program. For PostScript printers, press
CONTROL+D.
<p> Alternatively, you can put the program in
a file and type
<tscreen>
<tt>&tilde;&gt;<it/file/</tt>
</tscreen>
where <it/file/ is the name of the file
containing the program. After <tt/tip/
sends the file, press any required
end-of-file key.
</itemize>
</enum>
You should see something print. Do not worry if the
text does not look right; we will fix that later.
<sect2><heading>Enabling the Spooler: The <tt>/etc/printcap</tt> File
<label id="printing:printcap"></heading>
<p> 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.
You configure LPD by editing the file
<tt>/etc/printcap</tt>. The LPD spooling system reads
this file each time the spooler is used, so updates to the
file take immediate effect.
The format of the <tt/printcap/ file is straightforward.
Use your favorite text editor to make changes to
<tt>/etc/printcap</tt>. The format is identical to other
capability files like <tt>/usr/share/misc/termcap</tt> and
<tt>/etc/remote</tt>. For complete information about the
format, see the cgetent(3).
The simple spooler configuration consists of the following steps:
<enum>
<item>Pick a name (and a few convenient aliases) for
the printer, and put them in the
<tt>/etc/printcap</tt> file; see <ref
id="printing:naming" name="Naming the Printer">.
<item>Turn off header pages (which are on by default)
by inserting the <tt/sh/ capability; see <ref
id="printing:no-header-pages" name="Suppressing Header
Pages">.
<item>Make a spooling directory, and specify its
location with the <tt/sd/ capability; see <ref
id="printing:spooldir" name="Making the Spooling
Directory">.
<item>Set the <tt>/dev</tt> entry to use for the
printer, and note it in <tt>/etc/printcap</tt> with
the <tt/lp/ capability; see <ref id="printing:device"
name="Identifying the Printer Device">. Also, if the
printer is on a serial port, set up the communication
parameters with the <tt/fs/, <tt/fc/, <tt/xs/, and
<tt/xc/ capabilities; see <ref id="printing:commparam"
name="Configuring Spooler Communications Parameters">.
<item>Install a plain text input filter; see <ref
id="printing:textfilter" name="Installing the Text
Filter">
<item>Test the setup by printing something with the
<tt/lpr/ command; see <ref id="printing:trying"
name="Trying It Out"> and <ref
id="printing:troubleshooting" name="Troubleshooting">.
</enum>
<em/Note:/ 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.
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
<em/and/ print plain text jobs, you are strongly urged to
add an additional step to the simple setup outlined above:
install an automatic plain-text--to--PostScript (or other
printer language) conversion program. Section <ref
id="printing:advanced:if-conversion" name="Accommodating
Plain Text Jobs on PostScript Printers"> tells how to do
this.
<sect3><heading>Naming the Printer<label
id="printing:naming"></heading>
<p> 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.
At least one of the printers specified in the
<tt>/etc/printcap</tt> should have the alias
<tt/lp/. This is the default printer's name. If users
do not have the PRINTER environment variable nor
specify a printer name on the command line of any of the
LPD commands, then <tt/lp/ will be the default printer
they get to use.
Also, it is common practice to make the last alias for a
printer be a full description of the printer, including
make and model.
Once you have picked a name and some common aliases, put
them in the <tt>/etc/printcap</tt> 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.
In the following example, we start with a skeletal
<tt>/etc/printcap</tt> that defines two printers (a
Diablo 630 line printer and a Panasonic KX-P4455
PostScript laser printer):
<code>
#
# /etc/printcap for host rose
#
rattan|line|diablo|lp|Diablo 630 Line Printer:
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:
</code>
In this example, the first printer is named <tt/rattan/
and has as aliases <tt/line/, <tt/diablo/, <tt/lp/, and
<tt/Diablo 630 Line Printer/. Since it has the alias
<tt/lp/, it is also the default printer. The second is
named <tt/bamboo/, and has as aliases <tt/ps/, <tt/PS/,
<tt/S/, <tt/panasonic/, and <tt/Panasonic KX-P4455
PostScript v51.4/.
<sect3><heading>Suppressing Header Pages<label
id="printing:no-header-pages"></heading>
<p> The LPD spooling system will by default print a
<em/header page/ 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.
To suppress header pages, add the <tt/sh/ capability to
the entry for the printer in
<tt>/etc/printcap</tt>. Here is the example
<tt>/etc/printcap</tt> with <tt/sh/ added:
<code>
#
# /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:
</code>
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.
<sect3><heading>Making the Spooling Directory<label
id="printing:spooldir"></heading>
<p> The next step in the simple spooler setup is to make a
<em/spooling directory/, a directory where print jobs
reside until they are printed, and where a number of
other spooler support files live.
Because of the variable nature of spooling directories,
it is customary to put these directories under
<tt>/var/spool</tt>. It is not necessary to backup the
contents of spooling directories, either. Recreating
them is as simple as running <tt/mkdir/.
It is also customary to make the directory with a name
that is identical to the name of the printer, as shown
below:
<tscreen>
<tt>mkdir /var/spool/<it>printer-name</it></tt>
</tscreen>
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
<tt/rattan/ and <tt/bamboo/:
<tscreen><verb>
mkdir /var/spool/lpd
mkdir /var/spool/lpd/rattan
mkdir /var/spool/lpd/bamboo
</verb></tscreen>
<em/Note:/ 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:
<tscreen><verb>
chown daemon.daemon /var/spool/lpd/rattan
chown daemon.daemon /var/spool/lpd/bamboo
chmod 770 /var/spool/lpd/rattan
chmod 770 /var/spool/lpd/bamboo
</verb></tscreen>
Finally, you need to tell LPD about these directories
using the <tt>/etc/printcap</tt> file. You specify the
pathname of the spooling directory with the <tt/sd/
capability:
<code>
#
# /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:
</code>
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.
If you do not specify a spooling directory with <tt/sd/,
the spooling system will use <tt>/var/spool/lpd</tt> as
a default.
<sect3><heading>Identifying the Printer Device<label
id="printing:device"></heading>
<p> In section <ref id="printing:dev-ports" name="Adding
/dev Entries for the Ports">, we identified which
entry in the <tt>/dev</tt> 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).
List the <tt>/dev</tt> entry pathname in the
<tt>/etc/printcap</tt> file using the <tt/lp/
capability.
In our running example, let us assume that <tt/rattan/ is
on the first parallel port, and <tt/bamboo/ is on a
sixth serial port; here are the additions to
<tt>/etc/printcap</tt>:
<code>
#
# /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:
</code>
If you do not specify the <tt/lp/ capability for a
printer in your <tt>/etc/printcap</tt> file, LPD uses
<tt>/dev/lp</tt> as a default. <tt>/dev/lp</tt>
currently does not exist in FreeBSD.
If the printer you are installing is connected to a
parallel port, skip to the section <ref name="Installing
the Text Filter" id="printing:textfilter">. Otherwise,
be sure to follow the instructions in the next section.
<sect3><heading>Configuring Spooler Communication
Parameters<label id="printing:commparam"></heading>
<p> 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
<itemize>
<item>It lets you try different communication
parameters by simply editing the
<tt>/etc/printcap</tt> file; you do not have to
recompile the filter program.
<item>It enables the spooling system to use the same
filter program for multiple printers which may have
different serial communication settings.
</itemize>
The following <tt>/etc/printcap</tt> capabilities
control serial communication parameters of the device
listed in the <tt/lp/ capability:
<descrip>
<tag/<tt>br&num;<it/bps-rate/</tt>/
Sets the communications speed of the device to
<it/bps-rate/, where <it/bps-rate/ can be 50, 75,
110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
4800, 9600, 19200, or 38400 bits-per-second.
<tag/<tt>fc&num;<it/clear-bits/</tt>/
Clears the flag bits <it/clear-bits/ in the
<tt/sgttyb/ structure after opening the device.
<tag/<tt>fs&num;<it/set-bits/</tt>/
Sets the flag bits <it/set-bits/ in the <tt/sgttyb/
structure.
<tag/<tt>xc&num;<it/clear-bits/</tt>/
Clears local mode bits <it/clear-bits/ after opening
the device.
<tag/<tt>xs&num;<it/set-bits/</tt>/
Sets local mode bits <it/set-bits/.
</descrip>
For more information on the bits for the <tt/fc/,
<tt/fs/, <tt/xc/, and <tt/xs/ capabilities, see the file
<tt>/usr/include/sys/ioctl_compat.h</tt>.
When LPD opens the device specified by the <tt/lp/
capability, it reads the flag bits in the <tt/sgttyb/
structure; it clears any bits in the <tt/fc/ capability,
then sets bits in the <tt/fs/ capability, then applies
the resultant setting. It does the same for the local
mode bits as well.
Let us add to our example printer on the sixth serial
port. We will set the bps rate to 38400. For the flag
bits, we will set the TANDEM, ANYP, LITOUT, FLUSHO, and
PASS8 flags. For the local mode bits, we will set the
LITOUT and PASS8 flags:
<tscreen><verb>
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:\
:lp=/dev/ttyd5:fs#0x82000c1:xs#0x820:
</verb></tscreen>
<sect3><heading>Installing the Text Filter<label
id="printing:textfilter"></heading>
<p> We are now ready to tell LPD what text filter to use to
send jobs to the printer. A <em/text filter/, also
known as an <em/input filter/, 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 <tt/lp/
capability. The filter is expected to read the job from
standard input, perform any necessary translation for the
printer, and write the results to standard output, which
will get printed. For more information on the text
filter, see section <ref id="printing:advanced:filters"
name="Filters">.
For our simple printer setup, the text filter can be a
small shell script that just executes <tt>/bin/cat</tt>
to send the job to the printer. FreeBSD comes with
another filter called <tt/lpf/ 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
<tt/lpf/ is described in detail in section <ref
id="printing:advanced:lpf" name="lpf: a Text Filter">.
First, let uss make the shell script
<tt>/usr/local/libexec/if-simple</tt> be a simple text
filter. Put the following text into that file with your
favorite text editor:
<code>
#!/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 &ero;&ero; exit 0
exit 2
</code>
Make the file executable:
<tscreen><verb>
chmod 555 /usr/local/libexec/if-simple
</verb></tscreen>
And then tell LPD to use it by specifying it with the
<tt/if/ capability in <tt>/etc/printcap</tt>. We will add
it to the two printers we have so far in the example
<tt>/etc/printcap</tt>:
<code>
#
# /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:
</code>
<sect3><heading>Trying It Out<label id="printing:trying"></heading>
<p> 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 <tt/lpr/, which submits a job for printing.
You can combine <tt/lpr/ with the <tt/lptest/ program,
introduced in section <ref id="printing:testing"
name="Checking Printer Communications"> to generate some
test text.
<bf>To test the simple LPD setup:</bf>
<p> Type:
<tscreen>
<tt>lptest 20 5 | lpr -P<it/printer-name/</tt>
</tscreen>
where <it/printer-name/ is a the name of a printer (or
an alias) specified in <tt>/etc/printcap</tt>. To test
the default printer, type <tt/lpr/ without any <tt/-P/
argument. Again, if you are testing a printer that
expects PostScript, send a PostScript program in that
language instead of using <tt/lptest/. You can do so by
putting the program in a file and typing <tt/lpr
<it/file//.
For a PostScript printer, you should get the results
of the program. If you are using <tt/lptest/, then your
results should look like the following:
<tscreen><verb>
!"#$%&ero;'()*+,-./01234
"#$%&ero;'()*+,-./012345
#$%&ero;'()*+,-./0123456
$%&ero;'()*+,-./01234567
%&ero;'()*+,-./012345678
</verb></tscreen>
To further test the printer, try downloading larger
programs (for language-based printers) or running
<tt/lptest/ with different arguments. For example,
<tt/lptest 80 60/ will produce 60 lines of 80 characters
each.
If the printer did not work, see the next section, <ref
id="printing:troubleshooting" name="Troubleshooting">.
<sect3><heading>Troubleshooting<label
id="printing:troubleshooting"></heading>
<p> After performing the simple test with <tt/lptest/, you
might have gotten one of the following results instead of
the correct printout:
<descrip>
<tag/It worked, after awhile; or, it did not eject a full sheet./
The printer printed the above, but it sat for awhile
and did nothing. In fact, you might have needed to
press a PRINT REMAINING or FORM FEED button on the
printer to get any results to appear.
If this is the case, the printer was probably
waiting to see if there was any more data for your
job before it printed anything. To fix this
problem, you can have the text filter send a FORM
FEED character (or whatever is necessary) to the
printer. This is usually sufficient to have the
printer immediately print any text remaining in its
internal buffer. It is also useful to make sure each
print job ends on a full sheet, so the next job
does not start somewhere on the middle of the last
page of the previous job.
The following replacement for the shell script
<tt>/usr/local/libexec/if-simple</tt> prints a form
feed after it sends the job to the printer:
<code>
#!/bin/sh
#
# if-simple - Simple text input filter for lpd
# Installed in /usr/local/libexec/if-simple
#
# Simply copies stdin to stdout. Ignores all filter arguments.
# Writes a form feed character (\f) after printing job.
/bin/cat &ero;&ero; printf "\f" &ero;&ero; exit 0
exit 2
</code>
<tag/It produced the ``staircase effect.''/
You got the following on paper:
<tscreen><verb>
!"#$%&ero;'()*+,-./01234
"#$%&ero;'()*+,-./012345
#$%&ero;'()*+,-./0123456
</verb></tscreen>
You have become another victim of the <em/staircase
effect/, 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
<em/and/ ASCII code 13 (the carriage return or CR).
Many printers use the MS-DOS convention for
representing new-lines.
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.
Here is what FreeBSD wants your printer to do:
<tscreen><verb>
Printer received CR Printer prints CR
Printer received LF Printer prints CR + LF
</verb></tscreen>
Here are some ways to achieve this:
<itemize>
<item>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.
<p> <em/Note:/ If you boot your system into
other operating systems besides FreeBSD, you
may have to <em/reconfigure/ 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.
<item>Have FreeBSD's serial line driver
automatically convert LF to CR+LF. Of course,
this works with printers on serial ports
<em/only/. To enable this feature, set the
CRMOD bit in <tt/fs/ capability in the
<tt>/etc/printcap</tt> file for the printer.
<item>Send an <em/escape code/ 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.
<p> 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.
<code>
#!/bin/sh
#
# hpif - Simple text input filter for lpd for HP-PCL based printers
# Installed in /usr/local/libexec/hpif
#
# Simply copies stdin to stdout. Ignores all filter arguments.
# Tells printer to treat LF as CR+LF. Writes a form feed character
# after printing job.
printf "\033&ero;k2G" &ero;&ero; cat &ero;&ero; printf "\f" &ero;&ero; exit 0
exit 2
</code>
Here is an example <tt>/etc/printcap</tt> from
a host called orchid. It has a single printer
attached to its first parallel port, a Hewlett
Packard LaserJet 3Si named <tt/teak/. It is
using the above script as its text filter:
<code>
#
# /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:
</code>
</itemize>
<tag/It overprinted each line./
The printer never advanced a line. All of the lines
of text were printed on top of each other on one
line.
This problem is the ``opposite'' 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.
Use the printer's configuration switches or control
panel to enforce the following interpretation of LF
and CR characters:
<tscreen><verb>
Printer received CR Printer prints CR
Printer received LF Printer prints CR + LF
</verb></tscreen>
<tag/The printer lost characters./
While printing, the printer did nott print a few
characters in each line. The problem might have
gotten worse as the printer ran, losing more and
more characters.
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:
<itemize>
<item>If the printer supports XON/XOFF flow
control, have FreeBSD use it by specifying the
TANDEM bit in the <tt/fs/ capability.
<item>If the printer supports carrier flow
control, specify the MDMBUF bit in the <tt/fs/
capability. Make sure the cable connecting the
printer to the computer is correctly wired for
carrier flow control.
<item>If the printer does not support any flow
control, use some combination of the NLDELAY,
TBDELAY, CRDELAY, VTDELAY, and BSDELAY bits in
the <tt/fs/ capability to add appropriate delays
to the stream of data sent to the printer.
</itemize>
<tag/It printed garbage./
The printer printed what appeared to be random
garbage, but not the desired text.
This is usually another symptom of incorrect
communications parameters with a serial printer.
Double-check the bps rate in the <tt/br/ capability,
and the parity bits in the <tt/fs/ and <tt/fc/
capabilities; make sure the printer is using the
same settings as specified in the
<tt>/etc/printcap</tt> file.
<tag/Nothing happened./
If nothing happened, the problem is probably within
FreeBSD and not the hardware. Add the log file
(<tt/lf/) capability to the entry for the printer
you are debugging in the <tt>/etc/printcap</tt> file.
For example, here is the entry for <tt/rattan/, with
the <tt/lf/ capability:
<tscreen><verb>
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
</verb></tscreen>
Then, try printing again. Check the log file (in
our example, <tt>/var/log/rattan.log</tt>) to see
any error messages that might appear. Based on the
messages you see, try to correct the problem.
If you do not specify a <tt/lf/ capability, LPD uses
<tt>/dev/console</tt> as a default.
</descrip>
<sect><heading>Using Printers<label id="printing:using"></heading>
<p> This section tells you how to use printers you have setup with
FreeBSD. Here's an overview of the user-level commands:
<descrip>
<tag/<tt/lpr//
Print jobs
<tag/<tt/lpq//
Check printer queues
<tag/<tt/lprm//
Remove jobs from a printer's queue
</descrip>
There is also an administrative command, <tt/lpc/, described in
the section <ref id="printing:lpc" name="Administrating the
LPD Spooler">, used to control printers and their queues.
All three of the commands <tt/lpr/, <tt/lprm/, and <tt/lpq/
accept an option ``<tt/-P/ <it/printer-name/'' to specify on
which printer/queue to operate, as listed in the
<tt>/etc/printcap</tt> file. This enables you to submit,
remove, and check on jobs for various printers. If you do not
use the <tt/-P/ option, then these commands use the printer
specified in the PRINTER environment variable. Finally, if
you do not have a PRINTER environment variable, these commands
default to the printer named <tt/lp/.
Hereafter, the terminology <em/default printer/ means the
printer named in the PRINTER environment variable, or the
printer named <tt/lp/ when there is no PRINTER environment
variable.
<sect1><heading>Printing Jobs<label id="printing:lpr"></heading>
<p>
To print files, type
<tscreen>
<tt>lpr <it/filename.../</tt>
</tscreen>
This prints each of the listed files to the default printer.
If you list no files, <tt/lpr/ reads data to print from
standard input. For example, this command prints some
important system files:
<tscreen><verb>
lpr /etc/host.conf /etc/hosts.equiv
</verb></tscreen>
To select a specific printer, type
<tscreen>
<tt>lpr -P <it/printer-name/ <it/filename.../</tt>
</tscreen>
This example prints a long listing of the current directory
to the printer named <tt/rattan/:
<tscreen><verb>
ls -l | lpr -P rattan
</verb></tscreen>
Because no files were listed for the <tt/lpr/ command,
<tt/lpr/ read the data to print from standard input, which
was the output of the <tt/ls -l/ command.
The <tt/lpr/ 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 <ref id="printing:lpr:options"
name="Printing Options">.
<sect1><heading>Checking Jobs<label id="printing:lpq"></heading>
<p> When you print with <tt/lpr/, the data you wish to print
is put together in a package called a <em/print job/, 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.
To display the queue for the default printer, type <tt/lpq/.
For a specific printer, use the <tt/-P/ option. For
example, the command
<tscreen><verb>
lpq -P bamboo
</verb></tscreen>
shows the queue for the printer named <tt/bamboo/. Here is
an example of the output of the <tt/lpq/ command:
<tscreen><verb>
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
</verb></tscreen>
This shows three jobs in the queue for <tt/bamboo/. The
first job, submitted by user kelly, got assigned <em/job
number/ 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
<ref id="printing:lprm" name="Removing Jobs"> for details.
Job number nine consists of two files; multiple files given
on the <tt/lpr/ command line are treated as part of a single
job. It is the currently active job (note the word
<tt/active/ under the ``Rank'' column), which means the
printer should be currently printing that job. The second
job consists of data passed as the standard input to the
<tt/lpr/ command. The third job came from user mary; it is a
much larger job. The pathname of the files she's trying to
print is too long to fit, so the <tt/lpq/ command just shows
three dots.
The very first line of the output from <tt/lpq/ is also
useful: it tells what the printer is currently doing (or at
least what LPD thinks the printer is doing).
The <tt/lpq/ command also support a <tt/-l/ option to
generate a detailed long listing. Here is an example of
<tt/lpq -l/:
<tscreen><verb>
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
</verb></tscreen>
<sect1><heading>Removing Jobs<label
id="printing:lprm"></heading>
<p> If you change your mind about printing a job, you can
remove the job from the queue with the <tt/lprm/ command.
Often, you can even use <tt/lprm/ to remove an active job,
but some or all of the job might still get printed.
To remove a job from the default printer, first use <tt/lpq/
to find the job number. Then type
<tscreen>
<tt/lprm <it/job-number//
</tscreen>
To remove the job from a specific printer, add the <tt/-P/
option. The following command removes job number 10 from
the queue for the printer <tt/bamboo/:
<tscreen><verb>
lprm -P bamboo 10
</verb></tscreen>
The <tt/lprm/ command has a few shortcuts:
<descrip>
<tag/lprm -/
Removes all jobs (for the default printer) belonging to
you.
<tag/lprm <it/user//
Removes all jobs (for the default printer) belonging to
<it/user/. The superuser can remove other users' jobs;
you can remove only your own jobs.
<tag/lprm/
With no job number, user name, or ``<tt/-/'' appearing
on the command line, <tt/lprm/ removes the currently
active job on the default printer, if it belongs to
you. The superuser can remove any active job.
</descrip>
Just use the <tt/-P/ 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 <tt/rattan/:
<tscreen><verb>
lprm -P rattan -
</verb></tscreen>
<em/Note:/ If you are working in a networked environment,
<tt/lprm/ 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:
<code>
rose% lpr -P rattan myfile
rose% rlogin orchid
orchid% lpq -P rattan
Rank Owner Job Files Total Size
active seeyan 12 ... 49123 bytes
2nd kelly 13 myfile 12 bytes
orchid% lprm -P rattan 13
rose: Permission denied
orchid% logout
rose% lprm -P rattan 13
dfA013rose dequeued
cfA013rose dequeued
rose%
</code>
<sect1><heading>Beyond Plain Text: Printing Options<label
id="printing:lpr:options"></heading>
<p> The <tt/lpr/ 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.
<sect2><heading>Formatting and Conversion Options<label
id="printing:lpr:options:format"></heading>
<p> The following <tt/lpr/ 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 <tt/pr/ utility.
For example, the following command prints a DVI file (from
the TeX typesetting system) named <tt/fish-report.dvi/
to the printer named <tt/bamboo/:
<tscreen><verb>
lpr -P bamboo -d fish-report.dvi
</verb></tscreen>
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.
<em/Note:/ All of these options except <tt/-p/ and <tt/-T/
require conversion filters installed for the destination
printer. For example, the <tt/-d/ option requires the DVI
conversion filter. Section <ref
id="printing:advanced:convfilters" name="Conversion
Filters"> gives details.
<descrip>
<tag/<tt/-c// Print cifplot files.
<tag/<tt/-d// Print DVI files.
<tag/<tt/-f// Print FORTRAN text files.
<tag/<tt/-g// Print plot data.
<tag/<tt/-i <it/number///
Indent the output by <it/number/ columns; if you omit
<it/number/, indent by 8 columns. This option works
only with certain conversion filters.
<em/Note:/ Do not put any space between the <tt/-i/ and
the number.
<tag/<tt/-l//
Print literal text data, including control characters.
<tag/<tt/-n// Print ditroff (device independent troff) data.
<tag/-p/
Format plain text with <tt/pr/ before printing. See
pr(1) for more information.
<tag/<tt/-T <it/title///
Use <it/title/ on the <tt/pr/ header instead of the
file name. This option has effect only when used with
the <tt/-p/ option.
<tag/<tt/-t// Print troff data.
<tag/<tt/-v// Print raster data.
</descrip>
Here is an example: this command prints a nicely
formatted version of the <tt/ls/ manual page on the
default printer:
<tscreen><verb>
zcat /usr/share/man/man1/ls.1.gz | troff -t -man | lpr -t
</verb></tscreen>
The <tt/zcat/ command uncompresses the source of the
<tt/ls/ manual page and passes it to the <tt/troff/
command, which formats that source and makes GNU troff
output and passes it to <tt/lpr/, which submits the job to
the LPD spooler. Because we used the <tt/-t/ option to
<tt/lpr/, the spooler will convert the GNU troff output
into a format the default printer can understand when it
prints the job.
<sect2><heading>Job Handling Options<label
id="printing:lpr:options:job-handling"></heading>
<p> The following options to <tt/lpr/ tell LPD to handle the
job specially:
<descrip>
<tag/-&num; <it/copies//
Produce a number of <it/copies/ 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 <ref
id="printing:advanced:restricting:copies"
name="Restricting Multiple Copies">.
<p> This example prints three copies of <tt/parser.c/
followed by three copies of <tt/parser.h/ to the
default printer:
<tscreen><verb>
lpr -#3 parser.c parser.h
</verb></tscreen>
<tag/-m/
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.
<tag/-s/ Do not copy the files to the spooling directory,
but make symbolic links to them instead.
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.
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.
<em/Note:/ 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 <tt/-s/ option will save
space only on the local spooling directory, not the
remote. It is still useful, though.
<tag/-r/
Remove the files in the job after copying them to the
spooling directory, or after printing them with the
<tt/-s/ option. Be careful with this option!
</descrip>
<sect2><heading>Header Page Options<label
id="printing:lpr:options:misc"></heading>
<p> These options to <tt/lpr/ 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 <ref name="Header Pages"
id="printing:advanced:header-pages"> for information about
setting up header pages.
<descrip>
<tag/-C <it/text//
Replace the hostname on the header page with
<it/text/. The hostname is normally the name of the
host from which the job was submitted.
<tag/-J <it/text//
Replace the job name on the header page with
<it/text/. The job name is normally the name of the
first file of the job, or ``stdin'' if you are printing
standard input.
<tag/-h/
Do not print any header page. <em/Note:/ At some
sites, this option may have no effect due to the way
header pages are generated. See <ref name="Header
Pages" id="printing:advanced:header-pages"> for
details.
</descrip>
<sect1><heading>Administrating Printers<label
id="printing:lpc"></heading>
<p> As an administrator for your printers, you have had to
install, set up, and test them. Using the <tt/lpc/ command,
you can interact with your printers in yet more ways. With
<tt/lpc/, you can
<itemize>
<item>Start and stop the printers
<item>Enable and disable their queues
<item>Rearrange the order of the jobs in each queue.
</itemize>
First, a note about terminology: if a printer is
<em/stopped/, it will not print anything in its queue. Users
can still submit jobs, which will wait in the queue until
the printer is <em/started/ or the queue is cleared.
If a queue is <em/disabled/, no user (except root) can
submit jobs for the printer. An <em/enabled/ queue allows
jobs to be submitted. A printer can be <em/started/ for a
disabled queue, in which case it will continue to print jobs
in the queue until the queue is empty.
In general, you have to have root privileges to use the
<tt/lpc/ command. Ordinary users can use the <tt/lpc/
command to get printer status and to restart a hung printer
only.
Here is a summary of the <tt/lpc/ commands. Most of the
commands takes a <it/printer-name/ argument to tell on which
printer to operate. You can use <tt/all/ for the
<it/printer-name/ to mean all printers listed in
<tt>/etc/printcap</tt>.
<descrip>
<tag/<tt/abort <it/printer-name///
Cancel the current job and stop the printer. Users can
still submit jobs if the queue's enabled.
<tag/<tt/clean <it/printer-name///
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.
<tag/<tt/disable <it/printer-name///
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.
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 <tt/enable/ command.
<tag/<tt/down <it/printer-name/ <it/message...///
Take a printer down. Equivalent to <tt/disable/
followed by <tt/stop/. The <it/message/ appears as the
printer's status whenever a user checks the printer's
queue with <tt/lpq/ or status with <tt/lpc status/.
<tag/<tt/enable <it/printer-name///
Enable the queue for a printer. Users can submit jobs
but the printer will not print anything until it is started.
<tag/<tt/help <it/command-name///
Print help on the command <it/command-name/. With no
<it/command-name/, print a summary of the commands
available.
<tag/<tt/restart <it/printer-name///
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 <tt/stop/
or <tt/down/ commands. The <tt/restart/ command is
equivalent to <tt/abort/ followed by <tt/start/.
<tag/<tt/start <it/printer-name///
Start the printer. The printer will print jobs in its
queue.
<tag/<tt/stop <it/printer-name///
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.
<tag/<tt/topq <it/printer-name/ <it/job-or-username...///
Rearrange the queue for <it/printer-name/ by placing the
jobs with the listed <it/job/ numbers or the jobs
belonging to <it/username/ at the top of the queue. For
this command, you cannot use <tt/all/ as the
<it/printer-name/.
<tag/<tt/up <it/printer-name///
Bring a printer up; the opposite of the <tt/down/
command. Equivalent to <tt/start/ followed by
<tt/enable/.
</descrip>
<tt/lpc/ accepts the above commands on the command line. If
you do not enter any commands, <tt/lpc/ enters an interactive
mode, where you can enter commands until you type <tt/exit/,
<tt/quit/, or end-of-file.
<sect><heading>Advanced Printer Setup<label
id="printing:advanced"></heading>
<p> This section describes filters for printing specially
formatted files, header pages, printing across networks, and
restricting and accounting for printer usage.
<sect1><heading>Filters<label
id="printing:advanced:filter-intro"></heading>
<p> Although LPD handles network protocols, queuing, access
control, and other aspects of printing, most of the
<em/real/ work happens in the <em/filters/. 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 <ref id="printing:textfilter" name="Installing the
Text Filter">).
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 <em/you/ have to provide
filters yourself. The good news is that many are generally
available; when they are not, they are usually easy to write.
Also, FreeBSD comes with one, <tt>/usr/libexec/lpr/lpf</tt>,
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.
Here is what you will find in this section:
<itemize>
<item>Section <ref id="printing:advanced:filters"
name="How Fitlers Work">, 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
``under the hood'' 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.
<item>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 <ref
id="printing:advanced:if-conversion" name="Accommodating
Plain Text Jobs on PostScript Printers"> tells you what
you should do to overcome this problem. I recommend
reading this section if you have a PostScript printer.
<item>PostScript is a popular output format for many
programs. Even some people (myself included) write
PostScript code directly. But PostScript printers are
expensive. Section <ref id="printing:advanced:ps"
name="Simulating PostScript on Non-PostScript Printers">
tells how you can further modify a printer's text filter
to accept and print PostScript data on a
<em/non-PostScript/ printer. I recommend reading this
section if you do not have a PostScript printer.
<item>Section <ref id="printing:advanced:convfilters"
name="Conversion Filters"> 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 <tt/lpr -t/ to print troff data, or
<tt/lpr -d/ to print TeX DVI data, or <tt/lpr -v/ to
print raster image data, and so forth. I recommend
reading this section.
<item>Section <ref id="printing:advanced:of" name="Output
Filters"> tells all about a not often used feature of
LPD: output filters. Unless you are printing header
pages (see <ref id="printing:advanced:header-pages"
name="Header Pages">), you can probably skip that
section altogether.
<item>Section <ref id="printing:advanced:lpf" name="lpf:
a Text Filter"> describes <tt/lpf/, 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 <tt/lpf/.
</itemize>
<sect2><heading>How Filters Work<label
id="printing:advanced:filters"></heading>
<p> As mentioned before, a filter is an executable program
started by LPD to handle the device-dependent part of
communicating with the printer.
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 <tt/lf/ capability in <tt>/etc/printcap</tt>, or
<tt>/dev/console</tt> by default).
Which filter LPD starts and the filter's arguments depend
on what is listed in the <tt>/etc/printcap</tt> file and
what arguments the user specified for the job on the
<tt/lpr/ command line. For example, if the user typed
<tt/lpr -t/, LPD would start the troff filter, listed in
the <tt/tf/ capability for the destination printer. If
the user wanted to print plain text, it would start the
<tt/if/ filter (this is mostly true: see <ref
id="printing:advanced:of" name="Output Filters"> for
details).
There are three kinds filters you can specify in
<tt>/etc/printcap</tt>:
<itemize>
<item>The <em/text filter/, confusingly called the
<em/input filter/ 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:
<tscreen>
<tt>[-c] -w<it/width/ -l<it/length/ -i<it/indent/ -n <it/login/ -h <it/host/ <it/acct-file/</tt>
</tscreen>
where
<descrip>
<tag/<tt/-c//
appears if the job's submitted with <tt/lpr -l/
<tag/<tt/<it/width///
is the value from the <tt/pw/ (page width)
capability specified in <tt>/etc/printcap</tt>,
default 132
<tag/<tt/<it/length///
is the value from the <tt/pl/ (page length)
capability, default 66
<tag/<tt/<it/indent///
is the amount of the indentation from <tt/lpr -i/,
default 0
<tag/<tt/<it/login///
is the account name of the user printing the file
<tag/<tt/<it/host///
is the host name from which the job was submitted
<tag/<tt/<it/acct-file///
is the name of the accounting file from the <tt/af/
capability.
</descrip>
<item>A <em/conversion filter/ 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
<ref id="printing:advanced:convfilters"
name="Conversion Filters"> tells all about them.
Conversion filters also need to do accounting, if you
need printer accounting.
Conversion filters are started with the following
arguments:
<tscreen>
<tt>-x<it/pixel-width/ -y<it/pixel-height/ -n <it/login/ -h <it/host/ <it/acct-file/</tt>
</tscreen>
where <it/pixel-width/ is the value from the <tt/px/
capability (default 0) and <it/pixel-height/ is the
value from the <tt/py/ capability (default 0).
<item>The <em/output filter/ is used only if there is no
text filter, or if header pages are enabled. In my
experience, output filters are rarely used. Section
<ref id="printing:advanced:of" name="Output Filters">
describe them. There are only two arguments to an
output filter:
<tscreen>
<tt>-w<it/width/ -l<it/length/</tt>
</tscreen>
which are identical to the text filters <tt/-w/ and
<tt/-l/ arguments.
</itemize>
Filters should also <em/exit/ with the following exit
status:
<descrip>
<tag/exit 0/
If the filter printed the file successfully.
<tag/exit 1/
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.
<tag/exit 2/
If the filter failed to print the file and does not
want LPD to try again. LPD will throw out the file.
</descrip>
The text filter that comes with the FreeBSD release,
<tt>/usr/libexec/lpr/lpf</tt>, 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.
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.
<sect2><heading>Accommodating Plain Text Jobs on PostScript Printers
<label id="printing:advanced:if-conversion"></heading>
<p> 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.
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 <tt/&percnt;!/ (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.
How do we do this?
If you have got a serial printer, a great way to do it is to
install <tt/lprps/. <tt/lprps/ 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 ``toner low'' or ``paper jam''). But
more importantly, it includes a program called <tt/psif/
which detects whether the incoming job is plain text and
calls <tt/textps/ (another program that comes with
<tt/lprps/) to convert it to PostScript. It then uses
<tt/lprps/ to send the job to the printer.
<tt/lprps/ should be part of the FreeBSD ports collection
(see <ref id="ports" name="The Ports Collection">); if not,
it should be shortly. You can fetch, build and install it
yourself, of course. After installing <tt/lprps/, just
specify the pathname to the <tt/psif/ program that is part
of <tt/lprps/. If you installed <tt/lprps/ from the ports
collection, use the following in the serial PostScript
printer's entry in <tt>/etc/printcap</tt>:
<tscreen><verb>
:if=/usr/local/libexec/psif:
</verb></tscreen>
You should also specify the <tt/rw/ capability; that tells
LPD to open the printer in read-write mode.
If you have a parallel PostScript printer (and therefore
cannot use two-way communication with the printer, which
<tt/lprps/ needs), you can use the following shell script
as the text filter:
<code>
#!/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 &ero;&ero; cat &ero;&ero; printf "\004" &ero;&ero; exit 0
exit 2
else
#
# Plain text, convert it, then print it.
#
( echo $first_line; cat ) | /usr/local/bin/textps &ero;&ero; printf "\004" &ero;&ero; exit 0
exit 2
fi
</code>
In the above script, <tt/textps/ 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 <ref id="ports" name="The Ports
Collection">) includes a full featured text-to-PostScript
program called <tt/a2ps/ that you might want to
investigate.
<sect2><heading>Simulating PostScript on Non-PostScript Printers
<label id="printing:advanced:ps"></heading>
<p> PostScript is the <it/de facto/ standard for high
quality typesetting and printing. PostScript is, however,
an <em/expensive/ standard. Thankfully, Alladin
Enterprises has a free PostScript work-alike called
<it/Ghostscript/ 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.
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.
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.
Here is an example: the following script is a text filter
for Hewlett Packard DeskJet 500 printers. For other
printers, substitute the <tt/-sDEVICE/ argument to the
<tt/gs/ (Ghostscript) command. (Type <tt/gs -h/ to get a
list of devices the current installation of Ghostscript
supports.)
<code>
#!/bin/sh
#
# ifhp - Print Ghostscript-simulated PostScript on a DesJet 500
# Installed in /usr/local/libexec/hpif
#
# Treat LF as CR+LF:
#
printf "\033&ero;k2G" || exit 2
#
# Read first two characters of the file
#
read first_line
first_two_chars=`expr "$first_line" : '\(..\)'`
if [ "$first_two_chars" = "%!" ]; then
#
# It is PostScript; use Ghostscript to scan-convert and print it
#
/usr/local/bin/gs -dSAFER -dNOPAUSE -q -sDEVICE=djet500 -sOutputFile=- - \
&ero;&ero; 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 &ero;&ero; cat &ero;&ero; printf "\f" &ero;&ero; exit 2
fi
exit 2
</code>
Finally, you need to notify LPD of the filter via the
<tt/if/ capability:
<tscreen><verb>
:if=/usr/local/libexec/hpif:
</verb></tscreen>
That is it. You can type <tt/lpr plain.text/ and <tt/lpr
whatever.ps/ and both should print successfully.
<sect2><heading>Conversion Filters<label
id="printing:advanced:convfilters"></heading>
<p> After completing the simple setup described in <ref
name="Simple Printer Setup" id="printing:simple">, the
first thing you will probably want to do is install
conversion filters for your favorite file formats
(besides plain ASCII text).
<sect3><heading>Why Install Conversion Filters?</heading>
<p> 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:
<tscreen><verb>
dvips seaweed-analysis.dvi
lpr seaweed-analysis.ps
</verb></tscreen>
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:
<tscreen><verb>
lpr -d seaweed-analysis.dvi
</verb></tscreen>
We got LPD to do the DVI file conversion for us by
specifying the <tt/-d/ option. Section <ref
id="printing:lpr:options:format" name="Formatting and
Conversion Options"> lists the conversion options.
For each of the conversion options you want a printer to
support, install a <em/conversion filter/ and specify
its pathname in <tt>/etc/printcap</tt>. A conversion
filter is like the text filter for the simple printer
setup (see section <ref id="printing:textfilter"
name="Installing the Text Filter">) except that instead
of printing plain text, the filter converts the file
into a format the printer can understand.
<sect3><heading>Which Conversions Filters Should I Install?
</heading>
<p> 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.
The following table summarizes the filters that LPD
works with, their capability entries for the
<tt>/etc/printcap</tt> file, and how to invoke them with
the <tt/lpr/ command:
<code>
/etc/printcap
File type Capability lpr option
------------ ------------- ----------
cifplot cf -c
DVI df -d
plot gf -g
ditroff nf -n
FORTRAN text rf -f
troff tf -t
raster vf -v
plain text if none, -p, or -l
</code>
In our example, using <tt/lpr -d/ means the printer
needs a <tt/df/ capability in its entry in
<tt>/etc/printcap</tt>.
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 <tt/gf/
capability and then educate your users that <tt/lpr -g/
mean ``print Printerleaf files.''
<sect3><heading>Installing Conversion Filters</heading>
<p> Since conversion filters are programs you install
outside of the base FreeBSD installation, they should
probably go under <tt>/usr/local</tt>. The directory
<tt>/usr/local/libexec</tt> is a popular location, since
they they are specialized programs that only LPD will
run; regular users should not ever need to run them.
To enable a conversion filter, specify its pathname
under the appropriate capability for the destination
printer in <tt>/etc/printcap</tt>.
In our example, we will add the DVI conversion filter to
the entry for the printer named <tt/bamboo/. Here is the
example <tt>/etc/printcap</tt> file again, with the new
<tt/df/ capability for the printer <tt/bamboo/
<code>
#
# /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:
</code>
The DVI filter is a shell script named
<tt>/usr/local/libexec/psdf</tt>. Here is that script:
<code>
#!bin/sh
#
# 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 "$@"
</code>
This script runs <tt/dvips/ in filter mode (the <tt/-f/
argument) on standard input, which is the job to print.
It then starts the PostScript printer filter <tt/lprps/
(see section <ref id="printing:advanced:if-conversion"
name="Accommodating Plain Text Jobs on PostScript
Printers">) with the arguments LPD passed to this script.
<tt/lprps/ will use those arguments to account for the
pages printed.
<sect3><heading>More Conversion Filter Examples</heading>
<p> 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.
This example script is a raster (well, GIF file,
actually) conversion filter for a Hewlett Packard
LaserJet III-Si printer:
<code>
#!/bin/sh
#
# hpvf - Convert GIF files into HP/PCL, then print
# Installed in /usr/local/libexec/hpvf
PATH=/usr/X11R6/bin:$PATH; export PATH
giftopnm | ppmtopgm | pgmtopbm | pbmtolj -resolution 300 \
&& exit 0 \
|| exit 2
</code>
It works by converting the GIF file into a portable
anymap, converting that into a portable graymap,
converting that into a portable bitmap, and converting
that into LaserJet/PCL-compatible data.
Here is the <tt>/etc/printcap</tt> file with an entry for
a printer using the above filter:
<code>
#
# /etc/printcap for host orchid
#
teak|hp|laserjet|Hewlett Packard LaserJet 3Si:\
:lp=/dev/lpt0:sh:sd=/var/spool/lpd/teak:mx#0:\
:if=/usr/local/libexec/hpif:\
:vf=/usr/local/libexec/hpvf:
</code>
The following script is a conversion filter for troff
data from the groff typesetting system for the
PostScript printer named <tt/bamboo/:
<code>
#!/bin/sh
#
# pstf - Convert groff's troff data into PS, then print.
# Installed in /usr/local/libexec/pstf
#
exec grops | /usr/local/libexec/lprps "$@"
</code>
The above script makes use of <tt/lprps/ again to handle
the communication with the printer. If the printer were
on a parallel port, we would use this script instead:
<code>
#!/bin/sh
#
# pstf - Convert groff's troff data into PS, then print.
# Installed in /usr/local/libexec/pstf
#
exec grops
</code>
That is it. Here is the entry we need to add to
<tt>/etc/printcap</tt> to enable the filter:
<tscreen><verb>
:tf=/usr/local/libexec/pstf:
</verb></tscreen>
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 <tt/teak/:
<code>
#!/bin/sh
#
# hprf - FORTRAN text filter for LaserJet 3si:
# Installed in /usr/local/libexec/hprf
#
printf "\033&ero;k2G" &ero;&ero; fpr &ero;&ero; printf "\f" &ero;&ero; exit 0
exit 2
</code>
And we will add this line to the <tt>/etc/printcap</tt>
for the printer <tt/teak/ to enable this filter:
<tscreen><verb>
:rf=/usr/local/libexec/hprf:
</verb></tscreen>
Here is one final, somewhat complex example. We will add a
DVI filter to the LaserJet printer <tt/teak/ introduced
earlier. First, the easy part: updating
<tt>/etc/printcap</tt> with the location of the DVI
filter:
<tscreen><verb>
:df=/usr/local/libexec/hpdf:
</verb></tscreen>
Now, for the hard part: making the filter. For that, we
need a DVI-to-LaserJet/PCL conversion program. The
FreeBSD ports collection (see <ref id="ports" name="The
Ports Collection">) has one: <tt/dvi2xx/ is the name of
the package. Installing this package gives us the
program we need, <tt/dvilj2p/, which converts DVI into
LaserJet IIp, LaserJet III, and LaserJet 2000 compatible
codes.
<tt/dvilj2p/ makes the filter <tt/hpdf/ quite complex
since <tt/dvilj2p/ cannot read from standard input. It
wants to work with a filename. What iss worse, the
filename has to end in <tt/.dvi/ so using
<tt>/dev/fd/0</tt> for standard input is problematic.
We can get around that problem by linking (symbolically)
a temporary file name (one that ends in <tt/.dvi/) to
<tt>/dev/fd/0</tt>, thereby forcing <tt/dvilj2p/ to read
from standard input.
The only other fly in the ointment is the fact that we
cannot use /tmp for the temporary link. Symbolic links
are owned by user and group <tt/bin/. The filter runs
as user <tt/daemon/. And the <tt>/tmp</tt> 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.
Instead, the filter will make the symbolic link in the
current working directory, which is the spooling
directory (specified by the <tt/sd/ capability in
<tt>/etc/printcap</tt>). 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 <tt>/tmp</tt>.
Here, finally, is the filter:
<code>
#!/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$$.dvi
}
#
# Define a function to handle fatal errors: print the given message
# and exit 2. Exiting with 2 tells LPD to do not try to reprint the
# job.
#
fatal() {
echo "$@" 1>&ero;2
cleanup
exit 2
}
#
# If user removes the job, LPD will send SIGINT, so trap SIGINT
# (and a few other signals) to clean up after ourselves.
#
trap cleanup 1 2 15
#
# Make sure we are not colliding with any existing files.
#
cleanup
#
# Link the DVI input file to standard input (the file to print).
#
ln -s /dev/fd/0 hpdf$$.dvi || fatal "Cannot symlink /dev/fd/0"
#
# Make LF = CR+LF
#
printf "\033&ero;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
</code>
<sect3><heading>Automated Conversion: An Alternative To Conversion Filters
<label id="printing:advanced:autoconv"></heading>
<p> All these conversion filters accomplish a lot for your
printing environment, but at the cost forcing the user
to specify (on the <tt/lpr/ 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.
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 <tt/file/ can be of help here.
Of course, it will be hard to determine the differences
between <em/some/ file types---and, of course, you can
still provide conversion filters just for them.
The FreeBSD ports collection has a text filter that
performs automatic conversion called <tt/apsfilter/. It
can detect plain text, PostScript, and DVI files, run
the proper conversions, and print.
<sect2><heading>Output Filters<label
id="printing:advanced:of"></heading>
<p> 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
<itemize>
<item>LPD starts an output filter once for the entire
job instead of once for each file in the job.
<item>LPD does not make any provision to identify the
start or the end of files within the job for the
output filter.
<item>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:
<tscreen>
<tt>-w<it/width/ -l<it/length/</tt>
</tscreen>
where <it/width/ is from the <tt/pw/ capability and
<it/length/ is from the <tt/pl/ capability for the
printer in question.
</itemize>
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 <em/will not work/. Use a text filter (also
known as an input filter); see section <ref
id="printing:textfilter" name="Installing the Text
Filter">. Furthermore, an output filter is actually
<em/more complex/ 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.
However, an output filter is <em/necessary/ 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 <em/futile/ 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.)
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 <ref
id="printing:advanced:header-pages" name="Header Pages">)
only. LPD then expects the output filter to <em/stop
itself/ 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.
If there is an output filter but <em/no/ 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 <em/not/ what you want. In almost all
cases, you need a text filter.
The program <tt/lpf/, 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 <tt/lpf/. You
can also wrap <tt/lpf/ in a shell script to handle any
initialization codes the printer might require.
<sect2><heading><tt/lpf/: a Text Filter<label
id="printing:advanced:lpf"></heading>
<p> The program <tt>/usr/libexec/lpr/lpf</tt> that comes
with FreeBSD binary distribution is a text filter (input
filter) that can indent output (job submitted with <tt/lpr
-i/), allow literal characters to pass (job submitted with
<tt/lpr -l/), adjust the printing position for backspaces
and tabs in the job, and account for pages printed. It
can also act like an output filter.
<tt/lpf/ 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 <tt/lpf/.
In order for <tt/lpf/ to do page accounting correctly, it
needs correct values filled in for the <tt/pw/ and <tt/pl/
capabilities in the <tt>/etc/printcap</tt> 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 <ref
id="printing:advanced:acct" name="Accounting for Printer
Usage">.
<sect1><heading>Header Pages<label
id="printing:advanced:header-pages"></heading>
<p> If you have <em/lots/ of users, all of them using
various printers, then you probably want to consider
<em/header pages/ as a necessary evil.
Header pages, also known as <em/banner/ or <em/burst pages/
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.)
The LPD system can provide header pages automatically for
your printouts <em/if/ 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 <ref
id="printing:advanced:header-pages:ps" name="Header Pages on
PostScript Printers">.
<sect2><heading>Enabling Header Pages<label
id="printing:advanced:header-pages:enabling"></heading>
<p> In the <ref id="printing:simple" name="Simple Printer
Setup">, we turned off header pages by specifying
<tt/sh/ (meaning ``suppress header'') in the
<tt>/etc/printcap</tt> file. To enable header pages for
a printer, just remove the <tt/sh/ capability.
Sounds too easy, right?
You are right. You <em/might/ 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:
<code>
#!/bin/sh
#
# hpof - Output filter for Hewlett Packard PCL-compatible printers
# Installed in /usr/local/libexec/hpof
printf "\033&ero;k2G" || exit 2
exec /usr/libexec/lpr/lpf
</code>
Specify the path to the output filter in the <tt/of/
capability. See <ref id="printing:advanced:of"
name="Output Filters"> for more information.
Here is an example <tt>/etc/printcap</tt> file for the printer
<tt/teak/ that we introduced earlier; we enabled header
pages and added the above output filter:
<code>
#
# /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:
</code>
Now, when users print jobs to <tt/teak/, 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 <tt/lpr -h/; see <ref
id="printing:lpr:options:misc" name="Header Page Options">
for more <tt/lpr/ options.
<tt/Note:/ 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 <tt/ff/ capability in <tt>/etc/printcap</tt>.
<sect2><heading>Controlling Header Pages<label
id="printing:advanced:header-pages:controlling"></heading>
<p> By enabling header pages, LPD will produce a <em/long
header/, 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):
<tscreen><verb>
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
</verb></tscreen>
LPD appends a form feed after this text so the job starts
on a new page (unless you have <tt/sf/ (suppress form
feeds) in the destination printer's entry in
<tt>/etc/printcap</tt>).
If you prefer, LPD can make a <em/short header/; specify
<tt/sb/ (short banner) in the <tt>/etc/printcap</tt> file.
The header page will look like this:
<tscreen><verb>
rose:kelly Job: outline Date: Sun Sep 17 11:07:51 1995
</verb></tscreen>
Also by default, LPD prints the header page first, then
the job. To reverse that, specify <tt/hl/ (header last)
in <tt>/etc/printcap</tt>.
<sect2><heading>Accounting for Header Pages<label
id="printing:advanced:header-pages:accounting"></heading>
<p> Using LPD's built-in header pages enforces a particular
paradigm when it comes to printer accounting: header pages
must be <em/free of charge/.
Why?
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
<em/user or host/ information or an accounting file, so it
has no idea whom to charge for printer use. It is also not
enough to just ``add one page'' to the text filter or any
of the conversion filters (which do have user and host
information) since users can suppress header pages with
<tt/lpr -h/. They could still be charged for header pages
they did not print. Basically, <tt/lpr -h/ will be the
preferred option of environmentally-minded users, but you
cannot offer any incentive to use it.
It is <em/still not enough/ 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 <tt/lpr -h/, they will
still get them and be charged for them since LPD does not
pass any knowledge of the <tt/-h/ option to any of the
filters.
So, what are your options?
You can
<itemize>
<item>Accept LPD's paradigm and make header pages free.
<item>Install an alternative to LPD, such as LPDng or
PLP. Section <ref name="Alternatives to the Standard
Spooler" id="printing:lpd-alternatives"> tells more
about other spooling software you can substitute for
LPD.
<item>Write a <em/smart/ 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 <tt/af/
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 <tt/sh/ (short
header) capability in <tt>/etc/printcap</tt>.
Then again, all that might be too much trouble, and
users will certainly appreciate the more generous
system administrator who makes header pages free.
</itemize>
<sect2><heading>Header Pages on PostScript Printers<label
id="printing:advanced:header-pages:ps"></heading>
<p> 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.
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 <tt/lpr -h/.
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:
<code>
#!/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>&ero;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) ($date) ] {
270 y moveto show /y y 18 sub def
} forall
%
% That is it
%
restore
showpage
EOF
</code>
Now, each of the conversion filters and the text filter
can call this script to first generate the header page,
and then print the user's job. Here is the DVI conversion
filter from earlier in this document, modified to make a
header page:
<code>
#!/bin/sh
#
# DVI to PostScript printer filter
# Installed in /usr/local/libexec/psdf
#
# Invoked by lpd when user runs lpr -d
#
orig_args="$@"
fail() {
echo "$@" 1>&ero;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 $0` wrong." 1>&ero;2
exit 2
;;
esac
done
[ "$login" ] || fail "No login name"
[ "$host" ] || fail "No host name"
( /u/kelly/freebsd/printing/filters/make-ps-header $login $host "DVI File"
/usr/local/bin/dvips -f ) | eval /usr/local/libexec/lprps $orig_args
</code>
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 <ref id="printing:advanced:filters" name="How
Filters Work">).
As we have mentioned before, the above scheme, though fairly
simple, disables the ``suppress header page'' option (the
<tt/-h/ option) to <tt/lpr/. 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.
To allow users to shut off header pages on a per-job
basis, you will need to use the trick introduced in section
<ref id="printing:advanced:header-pages:accounting"
name="Accounting for Header Pages">: write an output
filter that parses the LPD-generated header page and
produces a PostScript version. If the user submits the
job with <tt/lpr -h/, 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.
If you have a PostScript printer on a serial line, you
can make use of <tt/lprps/, which comes with an output
filter, <tt/psof/, which does the above. Note that
<tt/psof/ does not charge for header pages.
<sect1><heading>Networked Printing<label
id="printing:advanced:network-printers"></heading>
<p> FreeBSD supports networked printing: sending jobs to
remote printers. Networked printing generally refers to two
different things:
<itemize>
<item>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 <ref id="printing:advanced:network:rm"
name="Printers Installed on Remote Hosts"> tells how to
do this.
<item>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:
<itemize>
<item>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 <ref
id="printing:advanced:network:rm" name="Printers
Installed on Remote Hosts"> to set up such a
printer.
<item>It might support a data stream network
connection. In this case, you ``attach'' the
printer to one host on the network by making that
host responsible for spooling jobs and sending them
to the printer. Section <ref
id="printing:advanced:network:net-if" name="Printers
with Networked Data Stream Interfaces"> gives some
suggestions on installing such printers.
</itemize>
</itemize>
<sect2><heading>Printers Installed on Remote Hosts<label
id="printing:advanced:network:rm"></heading>
<p> 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.
To enable this kind of remote printing, first install a
printer on one host, the <em/printer host/, using the
simple printer setup described in <ref
id="printing:simple" name="Simple Printer Setup">. Do any
advanced setup in <ref id="printing:advanced"
name="Advanced Printer Setup"> that you need. Make sure
to test the printer and see if it works with the features
of LPD you have enabled.
If you are using a printer with a network interface that is
compatible with LPD, then the <em/printer host/ in the
discussion below is the printer itself, and the
<em/printer name/ is the name you configured for the
printer. See the documentation that accompanied your
printer and/or printer-network interface.
Then, on the other hosts you want to have access to the
printer, make an entry in their <tt>/etc/printcap</tt>
files with the following:
<enum>
<item>Name the entry anything you want. For
simplicity, though, you probably want to use the same
name and aliases as on the printer host.
<item>Leave the <tt/lp/ capability blank, explicitly
(<tt/:lp=:/).
<item>Make a spooling directory and specify its
location in the <tt/sd/ capability. LPD will store
jobs here before they get sent to the printer host.
<item>Place the name of the printer host in the <tt/rm/
capability.
<item>Place the printer name on the <em/printer host/ in
the <tt/rp/ capability.
</enum>
That is it. You do not need to list conversion filters,
page dimensions, or anything else in the
<tt>/etc/printcap</tt> file.
Here is an example. The host rose has two printers,
<tt/bamboo/ and <tt/rattan/. We will enable users on the
host orchid to print to those printers. Here is the
<tt>/etc/printcap</tt> file for orchid (back from section
<ref id="printing:advanced:header-pages:enabling"
name="Enabling Header Pages">). It already had the entry
for the printer <tt/teak/; we have added entries for the two
printers on the host rose:
<code>
#
# /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:
</code>
Then, we just need to make spooling directories on orchid:
<tscreen><verb>
mkdir -p /var/spool/lpd/rattan /var/spool/lpd/bamboo
chmod 770 /var/spool/lpd/rattan /var/spool/lpd/bamboo
chown daemon.daemon /var/spool/lpd/rattan /var/spool/lpd/bamboo
</verb></tscreen>
Now, users on orchid can print to <tt/rattan/ and
<tt/bamboo/. If, for example, a user on orchid typed
<tscreen><verb>
lpr -P bamboo -d sushi-review.dvi
</verb></tscreen>
the LPD system on orchid would copy the job to the
spooling directory <tt>/var/spool/lpd/bamboo</tt> and note
that it was a DVI job. As soon as the host rose has room
in its <tt/bamboo/ 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.
<sect2><heading>Printers with Networked Data Stream Interfaces<label
id="printing:advanced:network:net-if"></heading>
<p> 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 <ref name="Printers
Installed on Remote Hosts" id="printing:advanced:network:rm">.
The format of the <tt>/etc/printcap</tt> 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.
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
<tt/netprint/ 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
<tt/netprint/. 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.).
<code>
#!/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', &ero;AF_INET, $printer_port, $address);
socket(PRINTER, &ero;PF_INET, &ero;SOCK_STREAM, $protocol)
|| die "Can't create TCP/IP stream socket: $!";
connect(PRINTER, $sockaddr) || die "Can't contact $printer_host: $!";
while (<STDIN>) { print PRINTER; }
exit 0;
</code>
We can then use this script in various filters. Suppose
we had a Diablo 750-N line printer connected to the
network. The printer accepts data to print on port number
5100. The host name of the printer is scrivener. Here is
the text filter for the printer:
<code>
#!/bin/sh
#
# diablo-if-net - Text filter for Diablo printer `scrivener' listening
# on port 5100. Installed in /usr/local/libexec/diablo-if-net
#
exec /usr/libexec/lpr/lpf "$@" | /usr/local/libexec/netprint scrivener 5100
</code>
<sect1><heading>Restricting Printer Usage<label
id="printing:advanced:restricting"></heading>
<p> 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.
<sect2><heading>Restricting Multiple Copies<label
id="printing:advanced:restricting:copies"></heading>
<p> The LPD system makes it easy for users to print multiple
copies of a file. Users can print jobs with <tt/lpr -&num;5/
(for example) and get five copies of each file in the job.
Whether this is a good thing is up to you.
If you feel multiple copies cause unnecessary wear and
tear on your printers, you can disable the <tt/-&num;/ option
to <tt/lpr/ by adding the <tt/sc/ capability to the
<tt>/etc/printcap</tt> file. When users submit jobs
with the <tt/-&num;/ option, they will see
<tscreen><verb>
lpr: multiple copies are not allowed
</verb></tscreen>
Note that if you have set up access to a printer remotely
(see section <ref name="Printers Installed on Remote
Hosts" id="printing:advanced:network:rm">), you need the
<tt/sc/ capability on the remote <tt>/etc/printcap</tt>
files as well, or else users will still be able to submit
multiple-copy jobs by using another host.
Here is an example. This is the <tt>/etc/printcap</tt>
file for the host rose. The printer <tt/rattan/ is quite
hearty, so we will allow multiple copies, but the laser
printer <tt/bamboo/'s a bit more delicate, so we will
disable multiple copies by adding the <tt/sc/ capability:
<code>
#
# /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:
</code>
Now, we also need to add the <tt/sc/ capability on the
host orchid's <tt>/etc/printcap</tt> (and while we are at
it, let us disable multiple copies for the printer
<tt/teak/):
<code>
#
# /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:
</code>
By using the <tt/sc/ capability, we prevent the use of
<tt/lpr -&num;/, but that still does not prevent users from
running <tt/lpr/ multiple times, or from submitting the
same file multiple times in one job like this:
<tscreen><verb>
lpr forsale.sign forsale.sign forsale.sign forsale.sign forsale.sign
</verb></tscreen>
There are many ways to prevent this abuse (including
ignoring it) which you are free to explore.
<sect2><heading>Restricting Access To Printers<label
id="printing:advanced:restricting:access"></heading>
<p> You can control who can print to what printers by using
the UNIX group mechanism and the <tt/rg/ capability in
<tt>/etc/printcap</tt>. Just place the users you want to
have access to a printer in a certain group, and then name
that group in the <tt/rg/ capability.
Users outside the group (including root) will be greeted
with
<tscreen><verb>
lpr: Not a member of the restricted group
</verb></tscreen>
if they try to print to the controlled printer.
As with the <tt/sc/ (suppress multiple copies) capability,
you need to specify <tt/rg/ on remote hosts that also have
access to your printers, if you feel it is appropriate (see
section <ref name="Printers Installed on Remote Hosts"
id="printing:advanced:network:rm">).
For example, we will let anyone access the printer
<tt/rattan/, but only those in group <tt/artists/ can use
<tt/bamboo/. Here is the familiar <tt>/etc/printcap</tt>
for host rose:
<code>
#
# /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:
</code>
Let us leave the other example <tt>/etc/printcap</tt> file
(for the host orchid) alone. Of course, anyone on orchid
can print to <tt/bamboo/. It might be the case that we
only allow certain logins on orchid anyway, and want them
to have access to the printer. Or not.
<em/Note:/ there can be only one restricted group per
printer.
<sect2><heading>Controlling Sizes of Jobs Submitted<label
id="printing:advanced:restricting:sizes"></heading>
<p> 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.
LPD enables you to limit the maximum byte size a file in a
job can be with the <tt/mx/ 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.
Note that the limit applies to <em/files/ in a job, and
<em/not/ the total job size.
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.
Let us add limits to our example printers <tt/rattan/ and
<tt/bamboo/. 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:
<code>
#
# /etc/printcap for host rose
#
#
# No limit on job size:
#
rattan|line|diablo|lp|Diablo 630 Line Printer:\
:sh:sd=/var/spool/lpd/rattan:\
:lp=/dev/lpt0:\
:if=/usr/local/libexec/if-simple:
#
# Limit of five megabytes:
#
bamboo|ps|PS|S|panasonic|Panasonic KX-P4455 PostScript v51.4:\
:sh:sd=/var/spool/lpd/bamboo:sc:rg=artists:mx#5000:\
:lp=/dev/ttyd5:fs#0x82000e1:xs#0x820:rw:\
:if=/usr/local/libexec/psif:\
:df=/usr/local/libexec/psdf:
</code>
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
<tt/mx/ capability in the remote <tt>/etc/printcap</tt>
files as well. See section <ref name="Printers Installed
on Remote Hosts" id="printing:advanced:network:rm"> for
more information on remote printing.
There is another specialized way to limit job sizes from
remote printers; see section <ref
id="printing:advanced:restricting:remote"
name="Restricting Jobs from Remote Printers">.
<sect2><heading>Restricting Jobs from Remote Printers<label
id="printing:advanced:restricting:remote"></heading>
<p> The LPD spooling system provides several ways to restrict
print jobs submitted from remote hosts:
<descrip>
<tag/Host restrictions/
You can control from which remote hosts a local LPD
accepts requests with the files
<tt>/etc/hosts.equiv</tt> and <tt>/etc/hosts.lpd</tt>.
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.
The format of these files is simple: one host name per
line. Note that the file <tt>/etc/hosts.equiv</tt> is
also used by the ruserok(3) protocol, and affects
programs like <tt/rsh/ and <tt/rcp/, so be careful.
For example, here is the <tt>/etc/hosts.lpd</tt> file
on the host rose:
<code>
orchid
violet
madrigal.fishbaum.de
</code>
This means rose will accept requests from the hosts
orchid, violet, and madrigal.fishbaum.de. If any
other host tries to access rose's LPD, LPD will
refuse them.
<tag/Size restrictions/
You can control how much free space there needs to
remain on the filesystem where a spooling directory
resides. Make a file called <tt/minfree/ 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.
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 <tt/minfree/ file.
For example, let us add a <tt/minfree/ file for the
printer <tt/bamboo/. We examine
<tt>/etc/printcap</tt> to find the spooling directory
for this printer; here is <tt/bamboo/'s entry:
<tscreen><verb>
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:
</verb></tscreen>
The spooling directory is the given in the <tt/sd/
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:
<tscreen><verb>
echo 6144 > /var/spool/lpd/bamboo/minfree
</verb></tscreen>
<tag/User restrictions/
You can control which remote users can print to local
printers by specifying the <tt/rs/ capability in
<tt>/etc/printcap</tt>. When <tt/rs/ appears in the
entry for a locally-attached printer, LPD will accept
jobs from remote hosts <em/if/ the user submitting the
job also has an account of the same login name on the
local host. Otherwise, LPD refuses the job.
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 <em/only/ your printers and not your
compute resources, you can give them ``token''
accounts, with no home directory and a useless shell
like <tt>/usr/bin/false</tt>.
</descrip>
<sect1><heading>Accounting for Printer Usage<label
id="printing:advanced:acct"></heading>
<p> 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?
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 <em/your/ requirements in charging for printer
usage.
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 <ref name="Filters"
id="printing:advanced:filter-intro">.
Generally, there are two ways to do accounting:
<itemize>
<item><em/Periodic accounting/ 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.
<item><em/Timely accounting/ 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 ``print quotas.''
But this method requires some database code to track
users and their quotas.
</itemize>
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.
<sect2><heading>Quick and Dirty Printer Accounting</heading>
<p> FreeBSD comes with two programs that can get you set up
with simple periodic accounting right away. They are the
text filter <tt/lpf/, described in section <ref
id="printing:advanced:lpf" name="lpf: a Text Filter">, and
<tt/pac/, a program to gather and total entries from
printer accounting files.
As mentioned in the section on filters (<ref
id="printing:advanced:filters" name="Filters">), 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 <tt/af/ capability in
<tt>/etc/printcap</tt>, and if not specified as an
absolute path, is relative to the spooling directory.
LPD starts <tt/lpf/ with page width and length arguments
(from the <tt/pw/ and <tt/pl/ capabilities). <tt/lpf/
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:
<tscreen><verb>
2.00 rose:andy
3.00 rose:kelly
3.00 orchid:mary
5.00 orchid:mary
2.00 orchid:zhang
</verb></tscreen>
You should use a separate accounting file for each
printer, as <tt/lpf/ has no file locking logic built into
it, and two <tt/lpf/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 <tt/af=acct/ in <tt>/etc/printcap</tt>.
Then, each accounting file will be in the spooling directory
for a printer, in a file named <tt/acct/.
When you are ready to charge users for printouts, run the
<tt/pac/ program. Just change to the spooling directory
for the printer you want to collect on and type <tt/pac/.
You will get a dollar-centric summary like the following:
<code>
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
</code>
These are the arguments <tt/pac/ expects:
<descrip>
<tag/<tt/-P<it/printer///
Which <it/printer/ to summarize. This option works
only if there is an absolute path in the <tt/af/
capability in <tt>/etc/printcap</tt>.
<tag/<tt/-c//
Sort the output by cost instead of alphabetically by
user name.
<tag/<tt/-m//
Ignore host name in the accounting files. With this
option, user smith on host alpha is the same user
smith on host gamma. Without, they are different users.
<tag/<tt/-p<it/price///
Compute charges with <it/price/ dollars per page or
per foot instead of the price from the <tt/pc/
capability in <tt>/etc/printcap</tt>, or two cents (the
default). You can specify <it/price/ as a floating
point number.
<tag/<tt/-r//
Reverse the sort order.
<tag/<tt/-s//
Make an accounting summary file and truncate the
accounting file.
<tag/<tt/<it/names...///
Print accounting information for the given user
<it/names/ only.
</descrip>
In the default summary that <tt/pac/ 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 <tt/pac -m/, to produce the following
summary:
<code>
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
</code>
To compute the dollar amount due, <tt/pac/ uses the
<tt/pc/ capability in the <tt>/etc/printcap</tt> file
(default of 200, or 2 cents per page). Specify, in
hundreths 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 <tt/pac/ with the <tt/-p/
option. The units for the <tt/-p/ option are in dollars,
though, not hundredths of cents. For example,
<tscreen><verb>
pac -p1.50
</verb></tscreen>
makes each page cost one dollar and fifty cents. You can
really rake in the profits by using this option.
Finally, running <tt/pac -s/ will save the summary
information in a summary accounting file, which is named
the same as the printer's accounting file, but with
<tt/_sum/ appended to the name. It then truncates the
accounting file. When you run <tt/pac/ again, it rereads
the summary file to get starting totals, then adds
information from the regular accounting file.
<sect2><heading>How Can You Count Pages Printed?</heading>
<p> 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.
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.
The text filter <tt/lpf/ (introduced in <ref
id="printing:advanced:lpf" name="lpf: a Text Filter">)
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 <tt/lpf/'s source
code.
How do you handle other file formats, though?
Well, for DVI-to-LaserJet or DVI-to-PostScript conversion,
you can have your filter parse the diagnostic output of
<tt/dvilj/ or <tt/dvips/ and look to see how many pages
were converted. You might be able to do similar things
with other file formats and conversion programs.
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.
So, what can you do?
There is only one <em/sure/ way to do <em/accurate/
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 <em/only/. There is no
line counting nor error-prone file examination required.
Of course, you can always be generous and make all
printouts free.
<sect><heading>Alternatives to the Standard Spooler<label
id="printing:lpd-alternatives"></heading>
<p> 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: ``What other spooling systems are out
there (and work with FreeBSD)?''
Unfortunately, I have located only <em/two/ alternatives---and
they are almost identical to each other! They are:
<descrip>
<tag/PLP, the Portable Line Printer Spooler System/
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 <htmlurl
url="ftp://ftp.iona.ie/pub/plp"
name="ftp://ftp.iona.ie/pub/plp">. There is also a <htmlurl
url="http://www.iona.ie:8000/www/hyplan/jmason/plp.html"
name="web page">.
It is quite similar to the BSD LPD spooler, but boasts a
host of features, including:
<itemize>
<item>Better network support, including built-in support
for networked printers, NIS-maintained printcaps, and
NFS-mounted spooling directories
<item>Sophisticated queue management, allowing multiple
printers on a queue, transfer of jobs between queues,
and queue redirection
<item>Remote printer control functions
<item>Prioritization of jobs
<item>Expansive security and access options
</itemize>
<tag/LPRng/
LPRng, which purportedly means ``LPR: the Next
Generation'' 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
<htmlurl url="ftp://dickory.sdsu.edu/pub/LPRng"
name="ftp://dickory.sdsu.edu/pub/LPRng">.
</descrip>
<sect><heading>Acknowledgments</heading>
<p> I would like to thank the following people who have assisted in
the development of this document:
<descrip>
<tag/Daniel Eischen <tt/&lt;deischen@iworks.interworks.org&gt;//
For providing a plethora of HP filter programs for perusal.
<tag/Jake Hamby <tt/&lt;jehamby@lightside.com&gt;//
For the Ghostscript-to-HP filter.
<tag/My wife, Mary Kelly <tt/&lt;urquhart@argyre.colorado.edu&gt;//
For allowing me to spend more time with FreeBSD than with her.
</descrip>
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