In this chapter, we examined the two major options for print servers, CUPS and LPD. CUPS is the new default Red Hat Linux print server. LPD, which has been the default for years , will be removed in a future release of Red Hat Linux, so it is important for you to learn about CUPS.
CUPS is short for the Common Unix Print System. It provides a common way for Linux and other Unix-type operating systems to work with the Internet Print Protocol (IPP). IPP is becoming the standard print server for a wide variety of operating systems, so it makes sense to move to CUPS.
CUPS includes a graphical browser-based tool available on port 631. With the CUPS tool, you can configure printers, classes of different printers, and print jobs. Print devices and drivers are available for a number of different connections and protocols. You can even configure a group of printers as a class; print jobs are automatically sent to the first available printer in that class.
CUPS configuration files are stored in the /etc/cups directory. While the main CUPS configuration file, cupsd.conf , is long, it is based on the same format as Apache configuration files. A substantial number of settings are available for everything from job size to logs to security.
Once you ve configured printers and print classes, it s easy to use the CUPS web-based configuration tool to manage printers and print jobs. For example, in the Jobs section, you can hold a print job to allow a higher priority job through. Alternatively, you can use redhat-config-printer . That all depends on the daemon setting shown in redhat-switch-printer . You can also check the status of current printers with the lpstat and lpadmin commands. If you activate the cups-lpd daemon, you can also use several basic LPD-style commands.
The Line Print Daemon is based on the LPRng-* RPM. You can configure printers by directly editing /etc/printcap.local , or you can use redhat-config-printer to write printer commands directly to /etc/printcap . You can manage the printers and queues with several basic commands, including lpr , lpq , lprm , and lpc .
In Chapter 26 , we ll look at mail servers and clients , with a focus on configuring sendmail for your network.