8.1. Printing files

8.1.1.1. Getting the file to the printer

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.

8.1.1.2. Status of your print jobs

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

8.1.1.3. Status of your printer

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

8.1.1.4. Removing jobs from the print queue

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.

8.1.2.1. Tools and languages

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.org, 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.

8.1.2.2. Previewing formatted files

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, or with KDE's kdvi.

• PDF files: xpdf, kpdf, gpdf or Adobe's viewer, acroread, which is also available for free but is not free software. Adobe's reader supports PDF 1.6, the others only support PDF versions up to 1.5. The version of a PDF file can be determined using the file command.

• From within applications, such as Firefox or OpenOffice, you can usually select Print Preview from one of the menus.