Thursday, April 9, 2009

Project: Building An All-Text Linux Workstation - Part 7

Today, we will finish up with printing by taking a look at the command line tools provided by CUPS.

CUPS supports two different families of printer tools. The first, Berkley or LPD comes from the Berkley Software Distribution (BSD) version of Unix and the second is SysV from the System V version of Unix. Both families include comparable functionality, so choosing one over the other is really a matter of personal taste.

Setting A Default Printer
A printer can be set as the default printer for the system. This will make using the command line print tools easier. To do this we can either use the web-based interface to CUPS at http://localhost:631 or we can use the following command:

lpadmin -d printer_name

where printer_name is the name of a print queue we defined in Part 6 of the series.

Sending A Job To The Printer (Berkley-Style)
The lpr program is used to send a job to the printer. It can accept standard input or file name arguments. One of the neat things about CUPS is that it can accept many kinds of data formats and can (within reason) figure out how to print them. Typical formats include PostScript, PDF, text, and images such as JPEG.

Here we will print a directory listing in three column format to the default printer:

ls /usr/bin | pr -3 | lpr

To use a different printer, append -P printer_name to the lpr command. To see a list of available printers:

lpstat -a

Sending A Job To The Printer (SysV-Style)
The SysV print system uses the lp command to send jobs to the printer. It can be used just as lpr in our earlier example:

ls /usr/bin | pr -3 | lp

however, lp has a different set of options. For example to specify a printer, the -d (for destination) option is used. lp also supports many options for page formatting and printer control not found with the lpr command.

Examining Print Job Status
While a print job is being printed, you may monitor its progress with the lpq command. This will display a list of all the jobs queued for printing. Each print job is assigned a job number that can be used with to control the job.

Terminating Print Jobs
Either the lprm (Berkley) or cancel (SysV) commands can be used to remove a job from a printer queue. While the two commands have different option sets, either command followed by a print job number will terminate the specified job.

Getting Help
The following man pages cover the CUPS printing commands

lp lpr lpq lprm lpstat lpoptions lpadmin cancel lpmove

In addition, CUPS provides excellent documentation of the printing system commands in the help section of the online interface to the CUPS server at:

http://localhost:631/help

Select the "Getting Started" link and the "Command Line Printing And Options" topic.

A Follow Up On Part 4
Midnight Commander allows direct access to its file viewer and built in text editor. The mcview command can be used to view files and the mcedit command can be used to invoke the editor.

Further Reading

Other installments in this series: 1 2 3 4 5 6 7 8 9 10 11 12 13 14