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Please take into considerations that once you save this page, it cannot keep up with the dynamics of the wiki. If you find something to be corrected or improved, you need to check or edit the actual current wiki-page.

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Usually, these snapshots are updated daily between 05:00 and 05:15 UTC

This snapshot was created: Sun Jul 20 06:08:07 CEST 2008

• 8.1. Printing files
  • 8.1.1. Command line printing
  • 8.1.2. Formatting
• 8.2. The server side
  • 8.2.1. General
  • 8.2.2. Graphical printer configuartion
  • 8.2.3. Buying a printer for Linux
• 8.3. Print problems
  • 8.3.1. Wrong file
  • 8.3.2. My print hasn't come out
• 8.4. Summary
• 8.5. Exercises

In this chapter we will learn more about printers and printing files. After reading this part, you will be able to:

• Format documents
• Preview documents before sending them to the printer
• Choose a good printer that works with your Linux system
• Print files and check on printer status
• Troubleshoot printing problems
• Find necessary documentation to install a printer

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Printing from within an application is very easy, selecting the Print option from the menu.

From the command line, use the lp or lpr command.

lp file(s)

lpr file(s)

These commands can read from a pipe, so you can print the output of commands using

command | lp

There are many options available to tune the page layout, the number of copies, the printer that you want to print to if you have more than one available, paper size, one-side or double-sided printing if your printer supports this feature, margins and so on. Read the man pages for a complete overview.

Once the file is accepted in the print queue, an identification number for the print job is assigned:

davy:~> lp /etc/profile
request id is blob-253 (1 file(s))

To view (query) the print queue, use the lpq or lpstat command. When entered without arguments, it displays the contents of the default print queue.

davy:~> lpq
blob is ready and printing
Rank	Owner	Job	File(s)		Total Size
active	davy	253	profile		1024 bytes
davy:~> lpstat
blob-253	davy	1024	Tue 25 Jul 2006 10:20_01 AM CEST

Which is the default printer on a system that has access to multiple printers?

lpstat -d

davy:~> lpstat -d
system default destination: blob

What is the status of my printer(s)?

lpstat -p

davy:~> lpstat -p
printer blob now printing blob-253. enabled since Jan 01 18:01

If you don’t like what you see from the status commands, use lprm or cancel to delete jobs.

davy:~> lprm 253

In the graphical environment, you may see a popup window telling you that the job has been canceled.

In larger environments, lpc may be used to control multiple printers. See the Info or man pages on each command.

There are many GUI print tools used as a front-end to lp, and most graphical applications have a print function that uses lp. See the built-in Help functions and program specific documentation for more.

• Why are there two commands for every task related to printing?
  • Printing on UNIX and alikes has a long history. There used to be two rather different approaches: the BSD-style printing and the SystemV-style printing. For compatibility, Linux with CUPS supports the commands from both styles. Also note that lp does not behave exactly like lpr, lpq has somewhat different options than lpstat and lprm is almost, but not quite, like cancel. Which one you use is not important, just pick the commands that you are comfortable with, or that you may know from previous experiences with UNIX-like systems.

If we want to get something sensible out of the printer, files should be formatted first. Apart from an abundance of formatting software, Linux comes with the basic UNIX formatting tools and languages.

Modern Linux systems support direct printing, without any formatting by the user, of a range of file types: text, PDF, PostScript and several image formats like PNG, JPEG, BMP and GIF.

For those file formats that do need formatting, Linux comes with a lot of formatting tools, such as the pdf2ps, fax2ps and a2ps commands, that convert other formats to PostScript. These commands can create files that can then be used on other systems that don’t have all the conversion tools installed.

Apart from these command line tools there are a lot of graphical word processing programs. Several complete office suites are available, many are free. These do the formatting automatically upon submission of a print job. Just to name a few: OpenOffice, KOffice, AbiWord, WordPerfect, etc.

The following are common languages in a printing context:

• groff: GNU version of the UNIX roff command. It is a front-end to the groff document formatting system. Normally it runs the troff command and a post-processor appropriate for the selected device. It allows generation of PostScript files.
• TeX and the macro package LaTeX: one of the most widely used markup languages on UNIX systems. Usually invoked as tex, it formats files and outputs a corresponding device-independent representation of the typeset document.
  Technical works are still frequently written in LaTeX because of its support for mathematic formulas, although efforts are being made at W3C (the World Wide Web Consortium) to include this feature in other applications.
• SGML and XML: Free parsers are available for UNIX and Linux. XML is the next generation SGML, it forms the basis for DocBook XML, a document system (this book is written in XML, for instance).

• Printing documentation
  • The man pages contain pre-formatted troff data which has to be formatted before it can roll out of your printer. Printing is done using the -t option to the man command: man -t command > man-command.ps Then print the PostScript file. If a default print destination is configured for your system/account, you can just issue the command man -t command to send the formatted page to the printer directly. For printing Info pages, refer to the Info pages on info (you will need the source code of the command).

Anything that you can send to the printer can normally be sent to the screen as well. Depending on the file format, you can use one of these commands:

• PostScript files: with the gv (GhostView) command.
• TeX dvi files: with xdvi.
• PDF files: xpdf or Adobe’s viewer, acroread, which is also available for free.
• From within applications, such as Firefox or OpenOffice, you can usually select Print Preview from one of the menus.

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Until a couple of years ago, the choice for Linux users was simple: everyone ran the same old LPD from BSD’s Net-2 code. Then LPRng became more popular, but nowadays most modern Linux distributions use CUPS, the Common UNIX Printing System. CUPS is an implementation of the Internet Printing Protocol (IPP), an HTTP-like RFC standard replacement protocol for the venerable (and clunky) LPD protocol. CUPS is distributed under the GNU Public License. CUPS is also the default print system on MacOS X.

Most distributions come with a GUI for configuring networked and local (parallel port or USB) printers. They let you choose the printer type from a list and allow easy testing. You don’t have to bother about syntax and location of configuration files. Check your system documentation before you attempt installing your printer.

CUPS can also be configured using a web interface that runs on port 631 on your computer. To check if this feature is enabled, try browsing to localhost:631/help or localhost:631/.

As more and more printer vendors make drivers for CUPS available, CUPS will allow easy connection with almost any printer that you can plug into a serial, parallel, or USB port, plus any printer on the network. CUPS will ensure a uniform presentation to you and your applications of all different types of printers.

Printers that only come with a Win9x driver could be problematic if they have no other support. Check with the hardware compatibility HOWTO when in doubt.

In the past, your best choice would have been a printer with native PostScript support in the firmware, since nearly all UNIX or Linux software producing printable output, produces it in PostScript, the publishing industry’s printer control language of choice. PostScript printers are usually a bit more expensive, but it is a device-independent, open programming language and you’re always 100% sure that they will work. These days, however, the importance of this rule of thumb is dwindling.

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In this section, we will discuss what you can do as a user when something goes wrong. We won’t discuss any problems that have to do with the daemon-part of the printing service, as that is a task for system administrators.

If you print the wrong file, the job may be canceled using the command lprm jobID, where jobID is in the form printername-printjobnumber (get it from information displayed by lpq or lpstat). This will work when other jobs are waiting to be printed in this printer’s queue. However, you have to be really quick if you are the only one using this printer, since jobs are usually spooled and send to the printer in only seconds. Once they arrive on the printer, it is too late to remove jobs using Linux tools.

What you can try in those cases, or in cases where the wrong print driver is configured and only rubbish comes out of the printer, is power off the printer. However, that might not be the best course of action, as you might cause paper jams and other irregularities.

Use the lpq command and see if you can spot your job:

elly:~> lpq
Printer: lp@blob
 Queue: 2 printable jobs
 Server: pid 29998 active
 Unspooler: pid 29999 active
 Status: waiting for subserver to exit at 09:43:20.699
 Rank   Owner/ID             Class Job Files          Size Time
1      elly@blob+997           A   997 (STDIN)         129 09:42:54
2      elly@blob+22            A    22 /etc/profile    917 09:43:20

Lots of printers have web interfaces these days, which can display status information by typing the printer’s IP address in your web browser:

Figure 8-1. Printer Status through web interface

• CUPS web interface versus printer web interface
  • Note that this is not the CUPS web interface and only works for printers supporting this feature. Check the documentation of your printer.

If your job ID is not there and not on the printer, contact your system administrator. If your job ID is listed in the output, check that the printer is currently printing. If so, just wait, your job will get done in due time.

If the printer is not printing, check that it has paper, check the physical connections to both electricity and data network. If that’s okay, the printer may need restarting. Ask your system admin for advice.

In the case of a network printer, try printing from another host. If the printer is reachable from your own host (see Chapter 10 for the ping utility), you may try to put the formatted file on it, like file.ps in case of a PostScript printer, using an FTP client. If that works, your print system is misconfigured. If it doesn’t work, maybe the printer doesn’t understand the format you are feeding it.

The GNU/Linux Printing site contains more tips and tricks.

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The Linux print service comes with a set of printing tools based on the standard UNIX LPD tools, whether it be the SystemV or BSD implementation. Below is a list of print-related commands.

Table 8-1. Printing related commands

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Configuring and testing printers involves being in the possession of one, and having access to the root account. If so, you may try:

• Installing the printer using the GUI on your system.
• Printing a test page using the GUI.
• Printing a test page using the lp command.
• Print from within an application, for example Mozilla or OpenOffice, by choosing File->Print from the menu.
• Disconnect the printer from the network or the local machine/print-server. What happens when you try to print something?

The following exercises can be done without printer or root access.

• Try to make PostScript files from different source files, (e.g. HTML, PDF, man pages). Test the results with the gv viewer.
• Check that the print daemon is running.
• Print the files anyway. What happens?
• Make a PostScript file using Mozilla. Test it with gv.
• Convert it to PDF format. Test with xpdf.
• How would you go about printing a GIF file from the command line?
• Use a2ps to print the /etc/profile file to an output file. Test again with gv. What happens if you don’t specify an output file?

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