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    1: **Contents**
    2: 
    3: [[!toc levels=3]]
    4: 
    5: # Printing
    6: 
    7: This chapter describes a simple configuration for printing, using an HP Deskjet
    8: 690C printer connected to the first parallel port and the lpd printing system
    9: that comes with NetBSD. First, the system will be configured to print text
   10: documents, and next the configuration will be extended to print PostScript
   11: documents using the Ghostscript program
   12: ([`print/ghostscript`](http://ftp.NetBSD.org/pub/pkgsrc/current/pkgsrc/print/ghostscript/README.html)).
   13: Please note that there are other, alternative printing systems available from
   14: the [packages collection](http://www.NetBSD.org/docs/software/packages.html),
   15: like LPRng
   16: ([`print/LPRng`](http://ftp.NetBSD.org/pub/pkgsrc/current/pkgsrc/print/LPRng/README.html))
   17: and the Common Unix Printing System (CUPS)
   18: ([`print/cups`](http://ftp.NetBSD.org/pub/pkgsrc/current/pkgsrc/print/cups/README.html))
   19: which are not covered here.
   20: 
   21: ## Enabling the printer daemon
   22: 
   23: After installation it is not yet possible to print, because the
   24: [[!template id=man name="lpd" section="8"]] printer
   25: spooler daemon is not enabled. To enable `lpd`, one line in the `/etc/rc.conf`
   26: file must be changed from:
   27: 
   28:     lpd=NO
   29: 
   30: to
   31: 
   32:     lpd=YES
   33: 
   34: Or rather, insert it, it won't be in your `rc.conf` by default.
   35: 
   36: The change will come into effect at the next boot, but the daemon can be started
   37: manually now:
   38: 
   39:     # sh /etc/rc.d/lpd start
   40: 
   41: To check if lpd is active, type the following command:
   42: 
   43:     # ps ax | grep lpd
   44:       179 ??  Is     0:00.01 lpd
   45: 
   46: If you don't see an entry for lpd in the output of the previous command, the
   47: daemon is not active.
   48: 
   49: The lpd system is configured via `/etc/printcap`. Before configuring
   50: `/etc/printcap` it is a good idea to make a printer test, to check if the
   51: physical connection between your computer and the printer is working. The test
   52: sends out some data directly to the printer device. Assuming you use a printer
   53: connected to the parallel port, this is `/dev/lpt0`; if you use an USB printer
   54: try `/dev/ulpt0`. Please check the manpages of these devices
   55: ([[!template id=man name="lpt" section="4"]],
   56: [[!template id=man name="ulpt" section="4"]])
   57: for more information!
   58: 
   59: In our example we have a printer attached to the parallel port, so we run this:
   60: 
   61:     # lptest 70 5 > /dev/lpt0
   62: 
   63: To see what the output should look like, try the same command without
   64: redirecting the output to the printer:
   65: 
   66:     # lptest 70 5
   67:     !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdef
   68:     "#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefg
   69:     #$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefgh
   70:     $%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghi
   71:     %&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghij
   72: 
   73: A frequent problem is that the output on the printer is not correctly aligned in
   74: columns but has a "staircase" configuration. This usually means that the printer
   75: is configured to begin a new line at the left margin after receiving both a
   76: `<CR\>` (carriage return, ASCII 13) character and a `<LF\>` (line feed, ASCII
   77: 10) character. NetBSD only sends a <LF\> character. You can fix this problem in
   78: two ways:
   79: 
   80:  * by changing the configuration of the printer
   81:  * by using a simple printer filter (described later)
   82: 
   83: *Note*: In the previous example the lpd spooler is not involved because the
   84: program output is sent directly to the printer device (`/dev/lpt0`) and is not
   85: spooled.
   86: 
   87: ## Configuring `/etc/printcap`
   88: 
   89: This section explains how to configure the example printer to print text
   90: documents.
   91: 
   92: The printer must have an entry in the `/etc/printcap` file; the entry contains
   93: the printer id (the name of the printer) and the printer description. The
   94: [[!template id=man name="lp" section="1"]]
   95: id is the default used by many programs. Here is an example entry:
   96: 
   97: **Example `/etc/printcap`**
   98: 
   99:     lp|local printer|HP DeskJet 690C:\
  100:             :lp=/dev/lpa0:sd=/var/spool/lpd/lp:lf=/var/log/lpd-errs:\
  101:             :sh:pl#66:pw#80:if=/usr/local/libexec/lpfilter:
  102: 
  103: The file format and options are described in detail in the
  104: [[!template id=man name="printcap" section="5"]]
  105: manpage. Please note that an *input filter* has been specified (with the `if`
  106: option) which will take care of eliminating the staircase problem:
  107: 
  108:     if=/usr/local/libexec/lpfilter
  109: 
  110: ### Printer driver and HP printers
  111: 
  112: The example above uses the `lpa0` device (polled driver) for the printer,
  113: instead of the `lpd0` (interrupt driven driver). Using interrupts there is a
  114: communication problem with some printers, and the HP Deskjet 690C is one of
  115: them: printing is very slow and one PostScript page can take hours. The problem
  116: is solved using the `lpa` driver. It is also possible to compile a custom kernel
  117: where lpt is polled.
  118: 
  119: The printcap entry for the printer also specifies a spool directory, which must
  120: be created; this directory will be used by the lpd daemon to accumulate the data
  121: to be printed:
  122: 
  123:     # cd /var/spool/lpd
  124:     # mkdir lp
  125:     # chown daemon:daemon lp
  126:     # chmod 770 lp
  127: 
  128: The only missing part is the `lpfilter` input filter, which must be written. The
  129: only task performed by this filter is to configure the printer for the
  130: elimination of the staircase problem before sending the text to be printed. The
  131: printer used in this example requires the following initialization string:
  132: `<ESC>&k2G`.
  133: 
  134: **Example `/usr/local/libexec/lpfilter`**
  135: 
  136:     #!/bin/sh
  137:     # Treat LF as CR+LF
  138:     printf "\033&k2G" && cat && exit 0
  139:     exit 2
  140: 
  141: After saving this script into the name you used in `/etc/printcap`, you need to
  142: make sure it's executable:
  143: 
  144:     # chmod 755 /usr/local/libexec/lpfilter*
  145: 
  146: *Note*: There is another filter that can be used:
  147: 
  148:     if=/usr/libexec/lpr/lpf:
  149: 
  150: This filter is much more complex than the one presented before. It is written to
  151: process the output of
  152: [[!template id=man name="nroff" section="1"]]
  153: and handles underline and overprinting, expands tab characters and converts `LF`
  154: to `CR + LF`. The source to this filter program can be found in
  155: `/usr/src/usr.sbin/lpr/filters/lpf.c`.
  156: 
  157: After everything is in place now, the
  158: [[!template id=man name="lptest" section="1"]]
  159: command can be run again now, this time using the
  160: [[!template id=man name="lpr" section="1"]] command,
  161: which will first send the data to the lpd spooler, then runs the filter and
  162: sends the data off to the printer:
  163: 
  164:     # lptest 70 5 | lpr -h
  165: 
  166: The `lpr` program prints text using the spooler to send data to the printer; the
  167: `-h` option turns off the printing of a banner page (not really necessary,
  168: because of the `sh` option in `/etc/printcap`). Users more familiar with the
  169: System V printing system can also use the
  170: [[!template id=man name="lp" section="1"]] command
  171: that comes as an alternative to
  172: [[!template id=man name="lpr" section="1"]].
  173: 
  174: ## Configuring Ghostscript
  175: 
  176: Now that basic printing works, the functionality for printing PostScript files
  177: can be added. The simple printer used in this example does not support native
  178: printing of PostScript files; a program must be used which is capable of
  179: converting a PostScript document in a sequence of commands that the printer
  180: understands. The Ghostscript program, which can be found in packages collection,
  181: can be used to this purpose. This section explains how to configure lpd to use
  182: Ghostscript to print PostScript files on the HP Deskjet 690C.
  183: 
  184: A second id for the printer will be created in `/etc/printcap`: this new id will
  185: use a different input filter, which will call Ghostscript to perform the actual
  186: print of the PostScript document. Therefore, text documents will be printed on
  187: the *lp* printer and PostScript documents on the *ps* printer: both entries use
  188: the same physical printer but have different printing filters.
  189: 
  190: The same result can be achieved using different configurations. For example, a
  191: single entry with only one filter could be used. For this, the filter should be
  192: able to automatically determine the format of the document being printed, and
  193: use the appropriate printing program. This approach is simpler but leads to a
  194: more complex filter; if you like it you should consider installing the
  195: magicfilter program from the packages collection: it does this and many other
  196: things automatically.
  197: 
  198: For our approach, the new `/etc/printcap` file looks like this:
  199: 
  200: **Example `/etc/printcap`**
  201: 
  202:     lp|local printer|HP DeskJet 690C:\
  203:             :lp=/dev/lpa0:sd=/var/spool/lpd/lp:lf=/var/log/lpd-errs:\
  204:             :sh:pl#66:pw#80:if=/usr/local/libexec/lpfilter:
  205:     
  206:     ps|Ghostscript driver:\
  207:             :lp=/dev/lpa0:sd=/var/spool/lpd/ps:lf=/var/log/lpd-errs:\
  208:             :mx#0:sh:if=/usr/local/libexec/lpfilter-ps:
  209: 
  210: Option `mx#0` is very important for printing PostScript files because it
  211: eliminates size restrictions on the input file; PostScript documents tend to be
  212: very big. The `if` option points to the new filter. There is also a new spool
  213: directory.
  214: 
  215: The next steps are the creation of the new spool directory and of the filter
  216: program. The procedure for the spool directory is the same as above:
  217: 
  218:     # cd /var/spool/lpd
  219:     # mkdir ps
  220:     # chown daemon:daemon ps
  221:     # chmod 770 ps
  222: 
  223: The filter program for PostScript output is more complex than the text base one:
  224: the file to be printed is fed to the interpreter which converts it into a
  225: sequence of commands in the printer's control language, and then sends that off
  226: to the printer. We have achieved to transform a cheap color printer in a device
  227: suitable for PostScript output, by virtue of the NetBSD operating system and
  228: some powerful freeware packages. The options used to configure Ghostscript are
  229: described in the Ghostscript documentation: `cdj550` is the device used to drive
  230: the HP printer.
  231: 
  232: **Example `/usr/local/libexec/lpfilter-ps`**
  233: 
  234:     #!/bin/sh
  235:     # Treat LF as CR+LF
  236:     printf "\033&k2G" || exit 2
  237:     # Print the postscript file
  238:     /usr/pkg/bin/gs -dSAFER -dBATCH -dQUIET -dNOPAUSE -q -sDEVICE=cdj550 \
  239:     -sOutputFile=- -sPAPERSIZE=a4 - && exit 0
  240:     exit 2
  241: 
  242: To summarize: two different printer names have been created on the system, which
  243: point to the same physical printer but use different options, different filters
  244: and different spool directories. Text files and PostScript files can be printed.
  245: To print PostScript files the Ghostscript package must be installed on the
  246: system.
  247: 
  248: ## Printer management commands
  249: 
  250: This section lists some useful BSD commands for printer and print jobs
  251: administration. Besides the already mentioned `lpr` and `lpd` commands, we
  252: have:
  253: 
  254:  * [[!template id=man name="lpq" section="1"]]
  255:    -- examine the printer job queue.
  256:  * [[!template id=man name="lprm" section="1"]]
  257:    -- delete jobs from the printer's queue.
  258:  * [[!template id=man name="lpc" section="8"]]
  259:    -- check the printing system, enable/disable printers and printer
  260:    features.
  261: 
  262: ## Remote printing
  263: 
  264: It is possible to configure the printing system in order to print on a printer
  265: connected to a remote host. Let's say that, for example, you work on the *wotan*
  266: host and you want to print on the printer connected to the *loge* host. The
  267: `/etc/printcap` file of loge is the one of the last example. From wotan it will
  268: be possible to print Postscript files using Ghostscript on loge.
  269: 
  270: The first step is to accept the print jobs submitted from the wotan host to the
  271: loge host. To accomplish this, a line with the wotan host name must be added to
  272: the `/etc/hosts.lpd` file on loge:
  273: 
  274:     # hostname
  275:     loge
  276:     # cat /etc/hosts.lpd
  277:     wotan
  278: 
  279: The format of this file is very simple: each line contains the name of a host
  280: which is permitted to print on the local system. By default the lpd daemon only
  281: listens on UNIX domain sockets for local connections, it won't accept any
  282: network connects. To ensure the daemon also accepts incoming network traffic,
  283: the following will need to be added to `/etc/rc.conf`:
  284: 
  285:     lpd_flags=""
  286: 
  287: Next, the `/etc/printcap` file on wotan must be configured in order to send
  288: print jobs to loge. For example:
  289: 
  290:     lp|line printer on loge:\
  291:         :lp=:sd=/var/spool/lpd/lp:lf=/var/log/lp-errs:\
  292:         :rm=loge:rp=lp
  293:     
  294:     ps|Ghostscript driver on loge:\
  295:         :lp=:sd=/var/spool/lpd/ps:lf=/var/log/lp-errs:\
  296:         :mx#0:\
  297:         :rm=loge:rp=ps
  298: 
  299: There are four main differences between this configuration and the earlier one:
  300: 
  301:  1. The definition of `lp` is empty.
  302:  2. The `rm` (remote machine) entry defines the name of the host to which the printer is connected.
  303:  3. The `rp` (remote printer) entry defines the name of the printer connected to the remote host.
  304:  4. It is not necessary to specify input filters because the definitions on the loge host will be used.
  305:  5. The spool directories must still be created locally on wotan:
  306: 
  307:         # cd /var/spool/lpd
  308:         # mkdir lp
  309:         # chown daemon:daemon lp
  310:         # chmod 770 lp
  311:         # mkdir ps
  312:         # chown daemon:daemon ps
  313:         # chmod 770 ps
  314: 
  315: Now the print jobs for the `lp` and `ps` queues on wotan will be sent
  316: automatically to the printer connected to loge.
  317: 

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