Summary

Printing under CentOS Linux is simple, provided that the CUPS printing environment is set up properly. You do have to learn a small set of commands to submit a print job and to check the status of pending print jobs. This chapter explained the CUPS printing system from the user's point of view and how to set everything up as a system administrator.

By reading this chapter, you learned the following things:

CentOS Linux comes with the CUPS printing system, which is an open-source implementation of a printing system based on the Internet Printing Protocol (IPP) and integrated with other tools such as Foomatic filter scripts and Ghostscript printer drivers.
As a user, you print with the lp or lpr command, check the status of the print queue with lpq or lpstat, cancel print jobs with lprm or cancel, and check the printer's status with lpc status.
Behind the scenes, the lp command sends the print file and a control file to the cupsd server (the print scheduler daemon), which places the files in a holding directory called the spool directory. Then cupsd processes the spooled print files through filters and sends them to the printer by using backend interface programs.
You can use the Red Hat printer configuration tool or the CUPS Web interface (http://localhost:631/) to set up printers.
CUPS relies on a number of configuration files, located in the /etc/cups directory, for its operation. This chapter explains these configuration files.