Printing under Linux

Although this is my personal opinion and I have not done scientific research on this topic, I would say that word processing is probably the computer activity which is done with the most frequency. E-mail may be surpassing the popularity of basic word processing (e-mail is just an extension of that, really). The fact is that people open up their word processor of choice (or the one they're forced to use at work) and write things on a pretty regular basis. Writing things, logically, means printing them afterwards. Despite what we're hearing about the web doing away with the printed material as we know it, it seems that we handle more paper not less of it in our networked world. After all, many people curl up in bed with a novel or a report for work. I don't see that custom being altered unless someone comes up with a comfortable way to use a computer in bed!

Obviously, if writing/word processing is so important and printing is the logical next step after writing, then getting your printer up and running under Linux is going to be a priority. Luckily, Linux has changed a great deal and hardware manufacturers got the idea quick that it didn't matter what OS people used their printers with, it was just important that they used them. That means that all of the major distributions offer first rate tools to get practically any printer running under Linux.

What you're doing when you print under Linux

Historically, printing in the Unix platforms started off as just sending plain text to a line printer, (resulting in rather plain looking text on paper with holes on each side - some of you might remember this). The basic means of printing in Linux just takes off from there. When you first set up your Linux machine to use a printer, you'll be configuring the lpr or "line printer". The lpr works with the lpd or "line printer daemon" running on your system. . A "daemon" is just a program that works in the background, without your direct intervention. This daemon just waits there for printing jobs to be sent to it, which it will then send to the lpq or "line printer queue". The queue (queue the British word for what Americans call a "waiting line") just puts your print job on hold until the system figures out the way to print it. This holding pattern is usually pretty quick - maybe a couple of seconds - because computers work pretty fast, generally.

As I mentioned, printing used to consist of just sending rather boring looking output to a line printer. Today's computing needs in terms of printing are much more demanding. Exotic fonts, graphics and other visual goodies can be found in standard printed material that comes from a computer. Your Linux machine should be capable of printing anything you want as long as you have the correct filters. For example, if you downloaded a report from the Save the Whales Foundation on the mating habits of the pilot whale in PDF format and you wanted to print it, you'll need some filters installed that know how to print PDF files. All mainstream Linux distributions come with Ghostscript. This is a free implementation of Adobe's Postscript filters. These filters are used to make sure that "What you see is what you get", to use a hackneyed expression.

How to print

If you want to print, you should push the "print" option in the menu. OK, you know that already. But how do we get from the point where you've got Linux installed to where you can print something with your word processor? Here are the steps.

1. Install a printer
Most Linux distributions come with tools that will get you printing in no time. As I mentioned before that Linux's printing system is based on basic line printing, you'll need a working "printcap" file (to be found in /etc/printcap, usually) that tells your system what printer it's supposed to work with. With SuSE you can use YAST to create this file (which will invoke a program called 'apsfilter'. Red Hat comes with "printtool", Mandrake has its printer setup tool in its main configuration package. Debian and Slackware both use the 'apsfilter' tool as well.

This lesson is not meant by any means to be the definitive list on products from every vendor, so if your particular distribution isn't listed here, you'll have to consult the documentation in your case.

For example, the /etc/printcap file that SuSE configured for my main machine at home is this:

printer1-ascii|lp1|y2prn_printer1.upp--ascii-printer1|y2prn_printer1.upp ascii:\
	:lp=/dev/lp0:\
	:sd=/var/spool/lpd/y2prn_printer1.upp--ascii-printer1:\
	:lf=/var/spool/lpd/y2prn_printer1.upp--ascii-printer1/log:\
	:af=/var/spool/lpd/y2prn_printer1.upp--ascii-printer1/acct:\
	:if=/var/lib/apsfilter/bin/y2prn_printer1.upp--ascii-printer1:\
	:la@:mx#0:\
	:tr=:cl:sh:
#
printer1|lp2|y2prn_printer1.upp--auto-printer1|y2prn_printer1.upp auto:\
	:lp=/dev/lp0:\
	:sd=/var/spool/lpd/y2prn_printer1.upp--auto-printer1:\
	:lf=/var/spool/lpd/y2prn_printer1.upp--auto-printer1/log:\
	:af=/var/spool/lpd/y2prn_printer1.upp--auto-printer1/acct:\
	:if=/var/lib/apsfilter/bin/y2prn_printer1.upp--auto-printer1:\
	:la@:mx#0:\
	:tr=:cl:sh:
#
printer1-raw|lp3|y2prn_printer1.upp--raw-printer1|y2prn_printer1.upp raw:\
	:lp=/dev/lp0:\
	:sd=/var/spool/lpd/y2prn_printer1.upp--raw-printer1:\
	:lf=/var/spool/lpd/y2prn_printer1.upp--raw-printer1/log:\
	:af=/var/spool/lpd/y2prn_printer1.upp--raw-printer1/acct:\
	:if=/var/lib/apsfilter/bin/y2prn_printer1.upp--raw-printer1:\
	:la@:mx#0:\
	:tr=:cl:sh:

2. Install the Ghostscript package and other useful filters
Most major distributions always recommend the Ghostscript package by default, so it goes on your system with a standard install. This will take care of your more advanced formatting needs. Other ones, like the jpeg libraries and other image formatting libraries are also installed by default so you can print your image files easily and painlessly.

3. Turn on the printer and press the print button
I sometimes forget to turn on the printer, so that's why I included this last part.

Some useful trouble shooting techniques

Most printers work from a parallel port. You must have parallel port support enabled in your kernel. Most major Linux distributions will install a generic kernel with this enabled. Printing therefore shouldn't be a problem. However, most people at some stage of the game prefer to compile and install their own custom Linux kernel. When you get up to speed on Linux and you decided to do this, always remember to include parallel port support into your new kernel. I have forgotten to do this (which ironically seems to happen with much more frequency as I get familiar with compiling kernels) only to find that I can't print anything when I've finished installing my new kernel.

I have also noticed my system choke on stuff sent to it from Corel WordPerfect. I won't go into the "hows" and "whys" (because I honestly don't know why or how this happens) but I have fell victim to an inability to print from WordPerfect on occasion. What I usually do is see if in fact I have pressed the button 'print' and something is waiting to be printed. To see if you have something waiting in the printer queue, just issue the command:

 lpq 

This will show you what's in the printer queue or if there is in fact anything there. Output generally looks something like this, if you have a problem (like my printer being unplugged, in this case).

waiting for printer1 to become ready (offline ?)
Rank   Owner      Job  Files                          Total Size
1st    bob       46    grocery_list.txt               667 bytes
2nd    bob       47    lyrics_to_sinatra_my_way.txt   2323 bytes

For example, if I wanted to just get rid of these files, shut WordPerfect down and start it up again and try printing again (which usually works for me), I would just issue the command:

 lprm 

Which removes the whole line printer queue. I could also be selective about it and only delete one of the print jobs by typing the command:

 lprm 47

Alas, my debut in the karaoke bar will have to wait, but I can still do the shopping. Hopefully you won't need to use these troubleshooting techniques very often, but they're good to know just in case.

Enjoy printing under Linux!

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