Accessing Printer Options via Multiple Print Queues

In Windows, you can usually set various printer options from a printing dialog box. Depending on the printer's features, you can set the resolution, determine whether to print in color or black-and-white, specify whether or not to use a duplexing feature, and so on. Unfortunately, these options aren't always available when printing from Linux, because these options may be features of the Ghostscript configuration. For instance, Ghostscript includes an option (-r) to set the resolution, and conventional Linux print queues don't provide a way to pass this information to the printer. (CUPS provides means to pass some options on to printers, but most Linux programs still aren't CUPS-enabled.) Fortunately, there is a way to access these options from Linux: You can create multiple print queues.

Linux print queues are logically unrelated to the physical printers—the queues are holding areas on disk and configurations for the printing software. It's entirely possible to link several queues to a single physical printer. For instance, suppose you've got an inkjet printer that supports several resolutions, ranging from 180 dots per inch (dpi) up to 1,440dpi. Inkjet printers usually print faster at lower resolutions, so you might want to use lower resolutions for draft printouts and higher resolutions for important final documents. In order to do this, you can create several queues for this printer, giving them names that indicate the intended resolution, such as epson180, epson360, epson720, and epson1440. Some smart filters and configuration tools enable you to set options such as the resolution when you create the filter; for instance, Apsfilter's option 6 (see Figure 13.2) does this job. Other tools let you change some of these options after creating the queue; for instance, this is one of the features of the CUPS printer configuration link that's available after a queue is created. With other tools or for some features, you may need to dig into the filter files, as described earlier in "Backtracking from /etc/printcap," to modify the call to Ghostscript or to add a feature in some other way.

In addition to accessing different print resolutions, you can create multiple queues to use a single printer via different Ghostscript drivers, to provide raw and Ghostscript-driven access, to provide options for features enabled through /etc/printcap such as the presence of a header page, and so on.

Tip Some PostScript printers (especially old models) don't work well with all PostScript input. If yours chokes or produces odd output from some applications, you can create two queues: a conventional queue that relies on PostScript in the printer and a second queue that uses Ghostscript to convert PostScript into PostScript using the pswrite driver. The latter option will probably be slow, but it may work better for some files if your printer is low on memory, has a buggy PostScript interpreter, or has some other problem processing some print jobs.

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