The Gentoo printing guide, at http://www.gentoo.org/doc/en/printing-howto.xml tells people to edit /etc/cupsd/cups.conf and change the setting of FileDevice to Yes, then specify the printer as "file:/dev/lp0" (or whatever device their printer happens to be). There are a couple of problems with this: 1. Security. CUPS warns against using FileDevice=Yes, because someone could print to, say, "file:/etc/passwd"; to quote from the CUPS system administrator manual, at: http://www.cups.org/doc-1.1/sam.html, "File devices are managed by the scheduler. Since the scheduler normally runs as the root user, file devices can be used to overwrite system files and potentially gain unauthorized access to the system. If you must create printers using file devices, we recommend that you set the FileDevice directive to Yes for only as long as you need to add the printers to the system, and then reset the directive to No." 2. It doesn't completely work. With file devices, CUPS doesn't support raw printing (as in the "-o raw" option to lpr); if you try, it just silently refuses, presumably for security reasons. (It'd be more dangerous to overwrite /etc/passwd with a raw file, which the user can control completely, than to overwrite it with a file encoded for printing.) This means that GIMP cannot print through its gimp-print module that uses "-o raw" to allow complete control of the printer (sending the appropriate codes to set print resolution, paper type, etc.). What CUPS wants people to do, instead of specifying the printer as a file device, as in "file:/dev/lp0", is for them to specify it as "parallel:/dev/lp0" or "serial:/dev/ttyS1?baud=115200" or "usb:/dev/usb/lp0". Unfortunately the exact syntax of this doesn't seem to be well documented, although the following web page has a tolerable description: http://www.linuxprinting.org/kpfeifle/LinuxKongress2002/Tutorial/VI.CUPS-Connec! Essentially the first part of the URI (e.g. "parallel" or "usb") designates the CUPS "backend" to be used, and the rest of the syntax is backend-specific. For USB, device names can also be specified as "usb://make/model" -- for instance, my printer is "usb://EPSON/Stylus%20COLOR%20860". I didn't come up with that string myself; the CUPS web interface gave it as one of the options. It is in fact the make and model of my printer, with spaces replaced by "%20"; but I wouldn't have known what to capitalize. And yes, the damn thing IS case-sensitive. The CUPS web interface gets the URI string by running the program /usr/lib/cups/backend/usb, which lists the available USB printers. You can do that yourself (running the program as root). The latter type of naming is useful in the case of multiple connected USB printers, each of which might end up as /dev/usb/lp0 or /dev/usb/lp1, depending on the order in which they were plugged in. Reproducible: Always Steps to Reproduce: 1. 2. 3.
I've done a rewrite on the printing howto; you can view it at http://www.gentoo.org/doc/en/handbook/draft/printing-howto.xml when the webnodes synchronise (less than an hour). It doesn't mention the FileDevice hack and uses the cups way of configuring printers. I've also removed the footmatic stuff since that is a cause of more confusion than help.
Fixed in CVS.
