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# cat /etc/fstab > | /dev/lp0

This command copies the /etc/fstab file to /dev/lp0, the most common identifier for a parallel printer. If your printer can print a text file, the result should be a printout of your /etc/fstab file. On some printers, status lights will blink but nothing will emerge. Frequently, pressing a button (marked Form Feed, Continue, or something similar) on the printer will cause the file to print. This happens because the printer didn't receive a full page of data, and so was waiting until it received more data to continue. This shouldn't happen in normal operation, though—just when testing the printer. Another problem is "stair-stepping," which is a printout that doesn't reset the line starts, like this:

/dev/hda1 / ext3 defaults 1 1

/dev/hda5 /home ext3 defaults 1 2

You might be able to figure out what went wrong here. Text files in Unix use just a newline (also known as a linefeed, ASCII code 10) to terminate each line. MS-DOS uses both a newline and a carriage return. Your printer was therefore set up to use MS-DOS-style line endings with both newline and carriage-return characters at the end of each line. In practice, CUPS normally filters newlines so that printers configured for DOS can understand them. If you still see this problem once you've fully configured printing, though, you can reconfigure your printer to properly return to the start of the line on receipt of a newline character. Often this is simply a matter of setting a dip switch. Check your printer manual. (Be careful about changing your printer characteristics if you use multiple operating systems.)

If you're using a USB printer, you can look for it with the lsusb command:

$ lsusb

Bus 005 Device 004: ID 04b8:0807 Seiko Epson Corp.

In practice, you're likely to see more output than this; however, this output shows a USB printer—an Epson RX500, to be precise. It's on USB bus 5, device 4. You can learn more about it by viewing the contents of /proc/bus/usb/devices, but most of the information in that file is likely to look like gibberish to the uninitiated. One feature to look for in this file, though, is Driver=usblp. If a line containing this string is present, it means that Linux has recognized the printer as a printer, which means that CUPS should be able to communicate with it. (Whether you can get output from the printer depends on the status of Ghostscript drivers, though.)

Finally, Ethernet printers can be treated just like other network devices. Specifically, you can use ping to verify that they're connected to the network. More substantial tests of their connectivity depend on the protocols the printer understands. Although low-level diagnostics of these protocols are possible, the simplest approach is usually to try configuring them, as described later in this chapter, in "Defining Printers in CUPS."

Configuring CUPS Security

Before proceeding with configuring CUPS to print, you should review your CUPS security and web-based configuration tool options. Unlike LPD systems, CUPS is best managed through its web-based configuration tool; however, this tool is sometimes disabled or set up in an inconvenient way. (Some distributions provide their own GUI tools for CUPS configuration. When using these distributions, you can either use their GUI tools or use the standard CUPS tools.) Depending on your network configuration, you might want to enable or disable the CUPS browsing feature, which enables CUPS servers to communicate their lists of available printers to one another. Browsing greatly simplifies network printer configuration and maintenance, but some distributions disable it by default. On the other hand, in a high-security environment or if your system is connected directly to the Internet, you might want to disable browsing, but some distributions enable it by default. In any event, you should review these settings and be sure they're set appropriately for your environment and needs.

Enabling web-based configuration

The main CUPS