On Sat, Nov 10, 2007 at 04:39:29PM -0700, Predrag Punosevac wrote: > I am trying to understand little bit better Unix printing. I am terribly > confused about > the real meaning of PPD files and printer drivers. > > According to this > http://en.wikipedia.org/wiki/PostScript_Printer_Description > > PPD files are post script description files that act as a drivers for post > script printers. This seems clear to me but I have never had a post > script printer in my life.
They are not really drivers but more files that describe the capabilities of the printer. > According to same page CUPS-PPD are used by CUPS to do post-script printing > on non-postscript printers by directing files through > CUPS-filter. Could somebody explain this things better to me. Every time I > used CUPS the PPD files where enough to enable me printing. > Did I really use some other drivers beside these PPD files or did CUPS > communicate with my printers with some generic driver and just > uses PPD files to do filtering. The latter. Cups uses the ghostscript program to translate postscript into something that the non-postscript printer can understand. > What is the simplest way to send ps file to the printer that doesn't speak > ps? If I could do that everything else is peace of cake. I read very > carefully printing form the handbook but I want to learn more. Use ghostscript. This is what both apsfilter and cups do. They've just made it a lot easier than doing it yourself. And as you can see from the size of both cups and apsfilter 'everything else' is a substantial piece of cake. > Could anybody explain me if there are some strong reasons for choosing LPD > over CUPS or LPRng system (seems just GUI added on the top of LPD) > It would logical to me that LPD is safer (CUPS port has some security > warnings) and maybe more reliable. In any case it is included in the base > system and I prefer to use something included in the base system In the past, lpd had a lot of security issues as well. I'm not sure if they're all solved. Both apsfilter and cups do more than standard lpd, which is only a printer spooler. Both cups and apsfilter look at what you're trying to print and try to convert it to a form suitable for printing. Standard lpr only understands a couple of ancient formats (ditroff, dvi, cif, plot) next to plain text. Roland -- R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725)
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