8.2.1 ASCII Printing Protocol

The ASCII protocol is the simplest protocol used, as well as the oldest. ASCII is also used to represent text files internally in the DOS, UNIX, and Windows operating systems. Therefore, data taken from a text file or a directory listing generally requires little preparation before being sent to the printer, other than a newline-to-carriage return/linefeed conversion for UNIX. Printers usually follow the DOS text file convention of the print head requiring an explicit carriage return character followed by a linefeed character at the end of a line of text. Since UNIX uses only the linefeed character to terminate text, an additional carriage return character must be added to the end of each line in raw text print output; otherwise, text prints in a stairstep output. (Some printers have hardware or software switches to do the conversion.)

8.2.2 PostScript Printing Protocol

Adobe introduced the PostScript language in 1985; it is used to enable the printout of high quality graphics and styled font text. PostScript is now the de-facto print standard in the UNIX community, and the only print standard in the Macintosh community. Numerous UNIX utilities exist to beautify and enhance text printing with PostScript. PostScript can be used to download font files into a printer as well as the data to be printed. PostScript commands can be sent to instruct the printer CPU to image, rotate, and scale complex graphics and images, thus freeing the host CPU. Scaling is particularly important with fonts since the document with the font has been produced on a computer screen with far lower resolution than the printer. For example, a 1024x768 computer screen on a 17-inch monitor allows for a resolution of approximately 82dpi, a modern desktop printer prints at a resolution of 600dpi. Therefore, a font must be scaled at least seven times larger for WYSIWYG output!

PostScript printers generally come with a number of resident fonts. For example, the NEC Silentwriter 95 contains Courier, Helvetica, ITC Avant Garde Gothic Book, ITC Bookman Light, New Century Schoolbook Roman, Palatino Roman, Times Roman, and several symbol fonts. These are stored in Read Only Memory (ROM) in the printer. When a page is printed from a Windows client that contains a font not in the printer, a font substitution table is used. If no substitute can be made, Courier is usually used. The user should be conscious of this when creating documents - documents with fonts not listed in the substitution table may cause other users problems when printing. Avoid use of strange fonts for documents that will be widely distributed.

The user program can choose to download different fonts as outline fonts to the PostScript printer if desired. Fonts that are commonly used by the user are often downloaded to PostScript printers that are connected directly to the user's computer, the fonts are then available to successive print jobs until the printer is turned off. When PostScript printers are networked, the clients must download any fonts desired with each print job. Since jobs come from different clients, the clients cannot assume that downloaded fonts will still be in the printer.

PostScript print jobs also contain a header that is sent describing the page layout, among other things. On a shared network printer, this header must also be downloaded with each print job. Although some PostScript drivers allow downloading of the header only once, this usually requires a bi-directional serial connection to the printer, instead of a unidirectional parallel connection.

PostScript print jobs can be sent either as binary data or as ASCII. The main advantage of binary data transmission is that it is faster. However, not all PostScript printers support it. Also, fonts can generally not be downloaded in binary. When FreeBSD is used as a printserver, ASCII PostScript printing should be selected on the clients, this is generally the default with most PostScript drivers.

The Adobe company licenses PostScript interpreters as well as resident fonts to printer manufacturers, and extracts a hefty license fee from any printer manufacturer who wants to use them in its printer. This presents both a benefit and a problem to the end user. Although a single company holding control over a standard can guarantee compliance, it does significantly raise the cost of the printer. As a result, PostScript has not met with much success in the lower-end laser and inkjet Windows printing market, despite the fact that Adobe distributes PostScript software operating system drivers for free.

One issue that is a concern when networking PostScript printers is the selection of banner page, (also known as header page, or burst page) printing. UNIX shared printing began with ASCII line printers, and since UNIX is a multiuser system, often many different user print jobs piled up in the printer output hopper. To separate these jobs the UNIX printing system programs support banner page printing if the client program that submits jobs asks for them. These pages print at the beginning or end of every print job and contain the username, submittal date, and so on.. By default, most clients, whether remote (e.g., a Windows LPR client) or local (e.g., the /usr/bin/lpr program) trigger a banner page to be printed. One problem is that some PostScript printers abort the entire job if they get unformatted ASCII text instead of PostScript. (In general, PostScript printers compatible with Hewlett-Packard Printer Control Language [HPPCL] handle banners without problems) Banner printing should be disabled for any printers with this problem, unless PostScript banner page printing is set up on the server.

8.2.3 HPPCL Printing Protocol

The Hewlett Packard company currently holds the largest market share of desktop inkjet and office laser printers. Back when Windows was released, HP decided to expand into the desktop laser jet market with the first LaserJet series of printers. At the time there was much pressure on Microsoft to use Adobe Type Manager for scaleable fonts within Windows, and to print PostScript to higher-end printers. Microsoft decided against doing this and used a technically inferior font standard, Truetype. They thought that it would be unlikely that the user would download fonts to the printer, since desktop Publishing was not being done on PC's at the time. Instead users would rasterize the entire page to the printer using whatever proprietary graphics printer codes the selected printer needed. HP devised HPPCL for their LaserJets, and make PostScript an add-on. The current revision of HPPCL now allows for many of the same scaling and font download commands that PostScript does. HP laser jet printers that support PostScript can be distinguished by the letter "M" in their model number. (M is for Macintosh, since Macintosh requires PostScript to print) For example, the HP 6MP has PostScript, the 6P doesn't.

HPPCL has almost no support in the UNIX applications market, and it is very unlikely that any will appear soon. One big reason is the development of the free Ghostscript PostScript interpreter. Ghostscript can take a PostScript input stream and print it on a PCL printer under UNIX. Another reason is the UNIX community's dislike of reinventing the wheel. HPPCL has no advantage over PostScript, and in many ways there are fewer problems with PostScript. Considering that PostScript can be added to a printer, either by hardware or use of Ghostscript, what is the point of exchanging an existing working solution for a slightly technically inferior one? Over the life of the printer, taking into account the costs of toner, paper, and maintenance, the initial higher cost of PostScript support is infinitesimal.

8.3.1 Printservers

The term "printserver" is one of those networking terms, like packet, that has been carelessly tossed around until its meaning has become somewhat confusing and blurred. To be specific, a printserver is simply a program that arbitrates print data from multiple clients for a single printer. Printservers can be implemented in one of the four methods described in the following sections.

8.3.2 Printspools

Printspooling is an integral part of network printing. Since the PC can spit out data much faster than the printer can accept it, the data must be buffered in a spool at some location. In addition, because many clients share printers, when clients send print jobs at the same time, jobs must be placed on a queue so that one can be printed after the other.

8.4.1 Windows 3.1/Windows for Workgroups 3.11

Several commercial TCP/IP stacks are available for Win31, that provide LPR client programs, in addition to the basic TCP/IP protocol to Win31. WfW has TCP/IP networking available for free from Microsoft, but it doesn't include an LPR client. Unfortunately, I have not come across a freeware implementation of a 16-bit Windows LPR client, so with the following instructions I use the Shareware program WLPRSPL available from http://www.winsite.com/info/pc/win3/winsock/wlprs41.zip. This program must be active during client printing, and is usually placed in the Startup group.

Organizations that want to use UNIX as a printserver to a group of Win31 clients without using a commercial or shareware LPR program have another option. The Microsoft Networking client for DOS used underneath Win31 contains SMB-based printing which is covered later in the chapter. DOS networking client setup and use are covered in Chapter 2 and Chapter 7.

If LPR-based client printing is desired and the organization doesn't want to upgrade to Win95, (which has several LPR clients available) the following instructions can be used. WLPRSPL needs a Winsock under Windows 3.1, so for the example I explain the setup of the Novell 16-bit TCP/IP client. The stack can be FTPed from Novell, and is easy to integrate into sites that already use the 16-bit NetWare networking client, usually NW 3.11 and 3.12. In most cases, however, sites that use NetWare + Win31 are probably best off printing through the NetWare server, then loading an LPR spooler as an Netware Loadable Module (NLM) to send the job over to FreeBSD.

As an alternate, the Microsoft Networking DOS 16-bit TCP/IP client under Win31 contains a Winsock, as does Microsoft TCP/IP for WfW. The target machine used here is a Compaq Deskpro 386/33 with 12MB of ram with an operating version of Windows 3.1, and a 3com 3C579 EISA network card. The instructions assume an LPR printserver on the network, named mainprinter.my.domain.com with a print queue named RAW.

Use the installation instructions in Exhibit 8.1 for a quick and dirty TCP/IP Winsock for Win31 systems. Administrators who already have the Novell IPX client installed should skip those steps.

8.4.2 Installation of the Novell TCP/IP Winsock client

8.4.3 Installation of the LPR client on 16-bit Windows with a Winsock installed

The following assumes a running Win31 installation with a Winsock or a running WfW installation with the 32-bit Microsoft TCP/IP protocol installed.

8.4.4 Installation of LPR client on Windows 95/98

The wlprspl program also can be used under Windows 95, but as a 16-bit program, it is far from an optimal implementation on a 32-bit operating system. In addition, Win95 and its derivatives fundamentally changed from Windows 3.1 in the printing subsystem. For these reasons I use a different LPR client program for Win95/98 LPR printing instructions. It is a full 32-bit print program, and it installs as a Windows 32-bit printer port monitor. The program is called ACITS LPR Remote Printing for Windows 95 and it is located at http://shadowland.cc.utexas.edu/acitslpr.htm.

ACITS stands for Academic Computing and Instructional Technologies Services. The ACITS LPR client includes software developed by the University of Texas at Austin and its contributors, it was written by Glenn K. Smith, a systems analyst with the Networking Services group at the university. The filename of the archive in the original program was ACITSLPR95.EXE and as of version 1.4 it was free for individuals or organizations to use for their internal printing needs. Since that time, it has gotten so popular that the university has taken over the program, incremented the version number (to get out from under the free license) and is now charging a $35 per copy fee for commercial use for the newer versions. The older free version can still be found on overseas FTP servers, such as http://www.go.dlr.de/fresh/pc/src/winsock/acitslpr95.exe.

It is likely that the cost of a shareware/commercial LPR program for Win95 plus the cost of Win95 itself will meet or exceed that of Win2K. As such, users wishing to print via LPR to FreeBSD UNIX systems will probably find it cheaper to simply upgrade to Windows NT Workstation or Win2K.

ACITS LPR and Win95 have a few printing idiosyncrasies. Most Win95 programs, such as Microsoft Word, expect print output to be spooled on the local hard drive and then metered out to a printer that is plugged into the parallel port. Network printing, on the other hand, assumes that print output will go directly from the application to the remote print server. Under Win95, local ports have a setting under Properties, Details, Spool Settings labeled "Print directly to the printer". If this is checked, the application running on the desktop (such as Microsoft Word) will not create a little Printer icon with pages coming out of it or use other means of showing the progress of the job as it is built. This can be very disconcerting to the user of a network printer, so this option should be checked only with printers plugged directly into the parallel port. Worse, if this is checked with ACITS, it can cause the job to abort if the remote print spooler momentarily goes offline.

Another local setting also should be changed. Generally, with local ports, Win95 builds the first page in the spooler and then starts printing it while the rest of the pages spool. If ACITS starts printing the first page while the rest of the pages are building, timeouts at the network layer can sometimes cause very large jobs to abort. The entire job should be set to completely spool before the LPR client passes it to the UNIX spooler. The problem is partly the result of program design: because ACITS is implemented as a local printer port instead of being embedded into Win95 networking (and available in Network Neighborhood) the program acts like a local printer port in some ways.

The LPR program can be set to deselect banner/burst page printing if a PostScript printer that cannot support ASCII is used. The burst pages referred to here are NOT generated by the Windows machine. Use the instructions in Exhibit 8.3 to install ACITS.

8.4.5 Installation of LPR client on Windows NT

Unlike WfW and Win95 TCP/IP, Windows NT--both server and workstation--includes an LPR client as well as an LPD program that allows incoming print jobs to be printed from LPR clients, such as UNIX systems.

To install the LPR client and daemon program under Windows NT 3.51, use the following instructions. The TCP/IP protocol should be installed beforehand and you must be logged in to the NT system as Administrator. This can be done at any time after the NT system is installed, or during OS installation:

To install the LPR client and daemon program under Windows NT 4, use the following instructions. The TCP/IP protocol should be installed beforehand and you must be logged in to the NT system as Administrator. This can be done at any time after the NT system is installed, or during OS installation:

Once LPR printing has been installed, the Printer icon or icons must be created on the NT system so that applications can print. Since this printer driver does all job formatting before passing the printing to the FreeBSD printserver, the print queues specified should be raw queues on the FreeBSD system, which don't do any job formatting.

To install the printer icon in Print Manager and set it to send print jobs to the FreeBSD UNIX system, use the following instructions under NT 3.51. You must be logged in to the NT system as Administrator. This can be done at any time after the NT system is installed, or during OS installation.

To install the printer icon in Print Manager and set it to send print jobs to the FreeBSD UNIX system, use the following instructions under NT 4. You must be logged in to the NT system as Administrator. This can be done at any time after the NT system is installed, or during OS installation:

The LPR client in Windows NT allows DOS print jobs originating in DOS boxes to be routed to the central UNIX print spooler. This is an advantage over the Win95 and WfW LPR programs.

8.7.1 Creating the spools

Building new print spools is merely a matter of making an entry in the /etc/printcap file, creating the spool directories, and setting the correct permissions on them. For example, the following additional line defines a PostScript printer named NEC (in addition to the lp definition):

#
lp|local line printer:\
    :lp=/dev/lpt0:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:

NEC|NEC Silentwriter 95 PostScript printer:\
    :lp=/dev/lpt0:sd=/var/spool/output/NEC:lf=/var/log/lpd-errs:
#

Because UNIX is case sensitive, NEC is different from nec in both the name of the printer and the name of the Spool directory. With the print spooler LPD, the Spool directories must be different from each other, or the spooler gets confused and doesn't print.

After the /etc/printcap is modified, the root user must create the /var/spool/output/NEC directory and assign ownership of it to the bin user, assign group ownership to daemon, and set permissions with the following commands:

% su root
# cd /var/spool/output
# mkdir NEC
# chown bin NEC     
# chgrp daemon NEC
# chmod 755 NEC

8.7.2 Additional spool capabilities

Because modern print jobs (especially PostScript) can sometimes reach hundreds of megabytes, the sd capability entry in the /etc/printcap file should always point to a Spool directory on a filesystem that has enough space. The /var directory on a default FreeBSD installation is generally set to a fairly small amount, which can easily overflow the spool. There are four ways to handle this problem:

1. During FreeBSD installation, if the administrator knows a lot of print jobs are going to go through the spooler, /var should be set to a large amount of free space.

2. Modify the sd capability in the /etc/printcap file to point to a spool directory in a different, larger filesystem, such as /usr/spool.

3. Use soft links to point the /var/spool/output directory to directories on a larger filesystem.

4. Don't define a /var directory at all during FreeBSD installation; this would make the installer link /var to /usr/var.

In addition to spools, the following other capabilities are usually placed in a production /etc/printcap file.

The entry fo prints a form feed when the printer is opened. It is handy for HPPCL (HP LaserJets) or other non-PostScript printers that are located behind electronic print sharing devices. It can also be used for printers that accept input from multiple connections, such as a parallel port, serial port, and localtalk port. An example is an HP LaserJet with an MIO card in it plugged into both Ethernet and LocalTalk networks. It will clear any garbage out of the printer before the job is processed.

The entry mx defines the maximum size of a print job, which is a must for modern print jobs that frequently grow far past the default print size of a megabyte. The original intent of this capability was to prevent errant programs from stuffing the spool with jobs so large that they would use up all paper in a printer. Graphics-heavy print jobs have made it impossible to depend on this kind of space limitation, so mx is usually set to zero, which turns it off.

The entry sh suppresses printing of banner pages in case the printer cannot handle ASCII and the client mistakenly requests them.

The entry ct denotes a TCP Connection timeout. This is useful if the remote print server doesn't close the connection properly.

8.7.3 Printing to hardware print server boxes or remote print servers.

Hardware print server boxes, such as the HP JetDirect internal and external cards, need some additional capabilities defined in the /etc/printcap entry; rp, for remote print spool, and rm for remote machine name.

The rm capability is simply the DNS or /etc/hosts name of the IP number associated with the remote printserver device. Obviously, print server devices, such as the HP JetDirect, must not use a dynamic TCP/IP network numbering assignment. If they get their numbering via DHCP, the IP number should be assigned from the static pool; it should always be the same IP number.

Determining the name used for rp, on the other hand, can be rather difficult. Here are some common names:

Windows NT Server: Printer name of the printer icon created in Print Manager

FreeBSD: Print queue name defined in /etc/printcap

HP JetDirect: Either the name TEXT or the name RAW. TEXT automatically converts incoming UNIX newline text to DOS-like CR/LF text that the printer can print. RAW should be used for PostScript, and HPPCL printing.

HP JetDirect EX +3: External, 3 port version of the JetDirect. Use RAW1, RAW2, RAW3, TEXT1, TEXT2, or TEXT3 depending on the port desired.

Intel NetPort: Either use TEXT for UNIX text conversion printing or use PASSTHRU for normal printing.

DPI: Use PORT1 or PORT2 depending on which port the printer is plugged into.

For other manufacturer's print servers refer to the manuals supplied with those devices.

The following is an example printcap that redefines the default lp print queue to send print jobs to the first parallel port on a remote HP LaserJet plugged into a JetDirect EX +3 named floor2hp4.biggy.com.

#
lp|local line printer:\
    :rm=floor2hp4.biggy.com:rp=RAW1:\
    :sd=/var/spool/output/lpd:\
    :lf=/var/log/lpd-errs:
#

8.7.4 Filters

The last two important printcap capabilities concern print filters, if (input filter) and of (output filter). If defined, incoming print jobs are run through the filters that these entries point to for further processing.

Filters are the reason that the UNIX print spooling system is so much more powerful than any other commercial server operating system. Under FreeBSD, incoming print jobs are acted on by any filters specified in the /etc/printcap no matter where they originate. Incoming print jobs from remote Windows, Mac, NT, OS/2 or other clients can be intercepted and manipulated by any program specified as a filter. Want a PostScript Printer? There's a filter that adds PostScript capability to a non-PostScript printer. Want to make a cheap Epson MX 80 dot-matrix emulate an expensive Okidata Microline dot-matrix for some archaic mainframe application? Write a filter that will rewrite the print codes to do it. Want custom-built banner pages? Use a filter. Many UNIX /etc/printcap filters on many Internet sites can do a variety of interesting and unique things. Someone may have already written a filter that does what you want!

#!/bin/sh
# /usr/local/libexec/crlfilter
#
# simple parlor trick to add CR to LF for printer
# Every line of standard input is printed with CRLF
# attached.
#

awk '{printf "%s\r\n", $0}' -

#!/bin/sh
# /usr/local/libexec/crlfilter
#
# Add CR to LF for printer
# Every line of standard input is printed with CRLF
# attached.
#
# Note, the ^M is a *real* ^M (^V^M if your typing in vi)
#

sed 's/$/^M/' -

#!/bin/sh
# 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&k2G" && cat && printf "\f" && exit 0

exit 2

#/etc/printcap
# The trailer (tr) is used when the queue empties.  I found that the
# form feed (\f) was basically required for the HP to print properly.
# Banners also need to be shut off.
#

lp|local line printer:\
    :lp=/dev/lpt0:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:
    :if=/usr/local/libexec/crlfilter:sh:tr=\f:mx#0:
#

#!/bin/sh
# Filename /usr/local/libexec/psbanner
# parameter spacing comes from if= filter call template of:
# if -c -w -l -i -n login -h host
# parsing trickiness is to allow for the presence or absence of -c
# sleep is in there for ickiness of some PostScript printers

for dummy
do
  case "$1" in
    -n) alogname="$2" ;;
    -h) ahostname="$2" ;;
  esac
  shift
done

/usr/local/libexec/make-ps-header $alogname $ahostname "PostScript" | \
  lpr -P lpnobanner

sleep 10

cat && exit 0

#!/bin/sh
# Filename /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

#
# 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
%

%
% 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
%

showpage

#
lp|local line printer, PostScript, banner:\
  :lp=/dev/lpt0:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:\
  :if=/usr/local/libexec/psbanner:sh:mx#0:

lpnobanner|local line printer, PostScript, no banner:\
  :lp=/dev/lpt0:sd=/var/spool/output/lpd-noban:\
  :lf=/var/log/lpd-errs:sh:mx#0:
#

8.9.1 Client access issues

Because a Windows client formats print jobs before sending them to the server, the administrator may want to hide some of the specialty print queues on the server. For example, the queue that converts LF to CRLF for UNIX text printouts would probably not be shared out. To make such queues invisible, the browseable=no option can be turned on in the smb.conf file. Also, the load printers option must be set to no to allow individual printer definitions.

Windows clients that print to Samba print queues on the UNIX system can view and cancel print jobs in the print queue. They cannot pause them, however, which is a difference between Novell and Windows NT Server print queues. They also cannot prioritize print jobs from the print queue window, although the administrator can reprioritize print jobs that are in the queue from a command shell on the FreeBSD server.

8.9.2 Printer entries in configuration files

Following are listings of sample /etc/printcap and smb.conf files used on the system to provide print services. An explanation of the interaction of these files follows.

#
#
# The printer in lpt0 is a PostScript printer.  The nec-crlf entry
# is for testing the printer when it is switched into HP LaserJet III
# mode.
#

lp|local line printer:\
  :lp=/dev/lpt0:sd=/var/spool/output/lpd:\
  :lf=/var/log/lpd-errs:sh:mx#0:

#

nec-crlf|NEC Silentwriter 95 in ASCII mode with UNIX text filter:\
  :lp=/dev/lpt0:sd=/usr/lpdspool/nec-crlf:\
  :lf=/var/log/lpd-errs:sh:mx#0:\
  :if=/usr/local/libexec/crlfilter:tr=\f:

#

nec-raw|NEC Silentwriter 95 used for PostScript passthrough printing:\
  :lp=/dev/lpt0:sd=/usr/lpdspool/nec-raw:\
  :lf=/var/log/lpd-errs:sh:mx#0:

#

nec-ps-banner|NEC Silentwriter 95 with PostScript banner page created:\
  :lp=/dev/lpt0:sd=/usr/lpdspool/nec-ps-banner:\
  :lf=/var/log/lpd-errs:sh:mx#0:if=/usr/local/libexec/psbanner:

#
#

[global]
comment = FreeBSD - Samba %v
log file = /var/log/samba.log
dont descend = /dev,/proc,/root,/stand
print command = lpr -s -P %p %s; rm %s
interfaces = X.X.X.X (the system IP number goes here)
printing = bsd
map archive = no
status = yes
public = yes
read only = no
preserve case = yes
strip dot = yes
security = share
guest ok = no
password level = 1
dead time = 15
domain master = yes
workgroup = WORKGROUP

[homes]
browseable = no
comment = User Home Directory
create mode = 0775
public = no

[printers]
path = /var/spool
comment = Printers
create mode = 0700
browseable = no
read only = yes
public = no

[lp]
printable = yes
browseable = no

[nec-raw]
comment = Main PostScript printer driver for Windows clients
printer driver = NEC SilentWriter 95
printable = yes
browseable = yes

[wwwroot]
path = /usr/local/www
read only = no
create mode = 0775
comment = Internal Web Server

8.9.3 Browsing output

Following is the output of a net view command executed at a DOS prompt under Windows 95:

Shared resources at \\SERVER

Sharename Type    Comment
--------------------------------------------------------------------
nec-crlf  Print   NEC Silentwriter 95 in ASCII mode
nec-raw   Print   Main PostScript printer driver
tedm      Disk    User Home Directory
wwwroot   Disk    Internal Web Server

The command was completed successfully.

In the /etc/printcap file four print queues are defined, all tied to the printer plugged into the parallel port on the FreeBSD server. The first is lp, the generic local line printer. Since this print queue generally has a filter placed on it to format jobs from the UNIX print queue properly, it should not be visible on the SMB network (i.e., visible in Network Neighborhood). The second queue, nec-crlf, has a filter that converts UNIX text to text that prints without stairstepping, so it also should be hidden from the SMB network. The third, nec-raw, should be visible on the network because this is the spool that the Windows clients use. The last queue, nec-ps-banner, is another specialty queue for UNIX local printing and thus should not be visible.

When the smb.conf file is parsed, the default entry [printers] is first read and used as a set of defaults for printers that are going to be shared out. Next, the /etc/printcap file is read to get a list of all printers on the server. Last, each printer is checked for a service name in the smb.conf file that contains settings that override the set of defaults.

In the listing of what resources are visible on the network, both nec-crlf and nec-raw print queues are visible, and lp and nec-ps-banner is not. lp is not visible because there is a specific entry, [lp] in the smb.conf file that blocks it. nec-ps-banner doesn't have such an entry, but because the print queue name is not a legal length for a SMB name, it isn't shared out either.

The nec-crlf printer is visible so as to illustrate another point - comments. If a print queue has no entry in the smb.conf file and is built by scanning the /etc/printcap file and using the [printers] defaults, the comment is taken from the /etc/printcap file next to the queue definition name. Otherwise, if an entry is made for the printer in the smb.conf file the comment is taken from the entry in smb.conf.

8.11.1 lp

The lp command is simply a front end command that calls the lpr command with appropriate options. Its main use is to allow the running of precompiled binary programs and scripts that assume that the lp command is the official printing command.

8.11.2 lpr

The lpr command is the main command that is used to print files from the command prompts under the FreeBSD operating system. It is frequently spawned off as a child program, or used in pipes. For example, when the Netscape web browser's Print button is clicked, Netscape may create the PostScript output, but the output goes through the lpr command.

The lpr command, like many UNIX command-line printing programs, assumes that the default print queue name is lp. When the FreeBSD machine is set up, the administrator usually sets the lp queue to print through a filter that allows raw UNIX text sent to it to print properly. For example, if an HP LaserJet printer that doesn't have PostScript is connected to the server, the lp queue specifies in the /etc/printcap file the CRLF filter listed earlier. On the other hand, if an Apple Laserwriter that doesn't support ASCII is connected to the server, the a2psfilter would be specified in the /etc/printcap for the lp queue.

When printing raw text files usually the -p option is specified to lpr. When printing preformatted files, such as PostScript files, the -P option is used, which selects whatever queue is used to handle these job types.

8.11.3 Managing the UNIX Print Queue

Once the print jobs coming in from clients are received on the FreeBSD system and placed in the print spool, they are metered out at a slower rate to the various printers. If traffic activity is light, and few print jobs get sent through, the administrator can probably ignore the print queue as long as it continues to work. However, a busy network printer running at an optimal rate of speed usually has a backlog of unprinted jobs in the queue waiting for print time. To keep all users happy and to provide for the occasional rush print job, the UNIX LPD/LPR printing system has several administration commands which are described here.

# lpq -a
nec-raw:
Rank Owner Job Files                         Total Size
1st  tedm  19  C:/WLPRSPL/SPOOL/~LP00018.TMP 105221 bytes
2nd  tedm  20  C:/WLPRSPL/SPOOL/~LP00019.TMP 13488 bytes
3rd  root  3   hosts                         1220 bytes
4th  tedm  1   Printer Test Page             765 bytes
5th  tedm  2   Microsoft Word - CHAPTE10.DOC 15411 bytes

# lprm -P nec-raw 19
dfA019tedmitte dequeued
cfA019dostest dequeued
# lprm -P nec-raw 3
dfA003toybox.placo.com dequeued
cfA003toybox.placo.com dequeued

# lpc
lpc> help
Commands may be abbreviated.
Commands are:
abort enable disable help restart status topq ?
clean exit down quit start stop up
lpc> help disable
disable turn a spooling queue off
lpc> help status
status show status of daemon and queue
lpc> exit

# lpc disable lp
lp:
queuing disabled

# lpq -a
lp:
Warning: lp is down: printing disabled
printing disabled
Rank Owner Job Files                      Total Size
1st  root  51  hosts                      1220 bytes
2nd  root  52  services                   60767 bytes
3rd  root  53  printcap                   2383 bytes
# cd /var/spool/output/lpd
# ls
.seq cfA053toybox.placo.com dfA053toybox.placo.com
cfA051toybox.placo.com dfA051toybox.placo.com lock
cfA052toybox.placo.com dfA052toybox.placo.com status
# lpr -P nec-raw dfA051toybox.placo.com
# lpr -P nec-raw dfA052toybox.placo.com
# lpr -P nec-raw dfA053toybox.placo.com
# lprm -P lp -
# lpq -a
nec-raw:
Warning: nec-raw is down: printing disabled
Warning: no daemon present
Rank Owner Job Files                      Total Size
1st  root  5   dfA051toybox.placo.com     1220 bytes
2nd  root  6   dfA052toybox.placo.com     60767 bytes
3rd  root  7   dfA053toybox.placo.com     2383 bytes

8.12.1 Ghostscript

The Ghostscript program, invoked as /usr/local/bin/gs, is one of the most useful printing utilities that have been developed for the free software community. Ghostscript reads incoming PostScript data, (or Adobe PDF files) interprets it, and outputs it as a raster image. This can be displayed on screen, for example, with the GhostView program under the X Window system, or printed on most graphics printers, such as Epson dot-matrix, HP DeskJet, or HP LaserJet. In effect, it is a way of adding PostScript printing capability to a printer that doesn't have PostScript firmware code. Ghostscript has been ported to numerous operating systems including Windows.

The Ghostscript home page is located at http://www.cs.wisc.edu/~ghost/ and contains the most current version of the program. A prebuilt FreeBSD binary of Ghostscript is located in the Packages section of the FreeBSD CDROM. This can be installed on the FreeBSD system by selecting the package from the prepackaged software list that is accessed through the /stand/sysinstall installation program. Many packaged programs on the CD depend on GhostScript, and so it may already be installed.

Installation of the packaged version of GhostScript is recommended in the FreeBSD ports Section because it has been tested with the other packages that require it. The package creates a directory containing some documentation files in /usr/local/share/ghostscript/X.XX/doc. Unfortunately, because of the packaging process on the FreeBSD CDROM not all the useful installation files are copied into this location. So, if the package was version 5.03 (for example) the administrator will also want to get the file ftp://ftp.cs.wisc.edu/ghost/aladdin/gs502/ghostscript-5.02.tar.gz, and unzip and untar it into a temporary directory.

Extracting the archive file creates a directory structure under the gs5.03 subdirectory. To install ghostscript in the /etc/printcap file, read the gs5.03/devs.mak file to determine which printer driver definition works with your printer and then use the following instructions:

8.12.2 a2ps filter

Another handy utility is the a2ps filter, short for ASCII-to-PostScript. This program takes an incoming ASCII datastream and converts it into PostScript. It can also print multiple pages on a single sheet of paper by shrinking them down. It is a useful tool for a printer that cannot interpret ASCII, such as a PostScript-only printer.

A2ps is not installed in the FreeBSD system by default; it is located in the ports section /usr/ports/print/a2ps43. A prepackaged binary can be installed with /stand/sysinstall but I have had problems with that port. It is best to install it by running make in the a2ps43 ports directory. A printcap entry and filter using this follow:

#
lp|local line printer with output dumped through a2ps for raw listings:\
  :lp=/dev/lpt0:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:sh:mx#0:\
  :if=/usr/local/libexec/ascii2postscript:
#

#!/bin/sh
#
# Simple filter that converts ASCII to PostScript for basic stuff like
# directory listings.
#

/usr/local/bin/a2ps && exit 0

exit 2

Read the system manual page for a2ps to see the options available with this program, and remember to set the filter script ascii2postscript all-executable.