[cups.general] How does CUPS work?

Space Ship Traveller space.ship.traveller at gmail.com
Wed May 20 05:58:35 PDT 2009


Hi,

Say I have a printer with some features, and a PPD which describes the  
features.

I can print to the printer via USB and have it connected to a CUPS  
server, and have it loaded with the appropriate PPD. So it is now  
available via http://192.168.1.153:631/printers/usbprinter

I then have a client such as OS X with a local CUPS server which I can  
load the printer into. This printer is loaded as IPP with the above  
URL. I also select the same PPD for use on the client.

I think my question revolves around my understanding of PPDs.

So, if I print a document, the PPD provides the application details  
about the printer such as output resolution. How does this work in  
general terms? For example, if I select 300 DPI, does this insert a  
command into the postscript data stream so that the printer will  
actually know to output 300DPI?

In the case that I select 300 DPI on the client, but on the server it  
is set to something else, say 600DPI, how is this resolved? Does the  
server see that it was set to 300 and change it to 600?

In the case that the client uses a PPD, should the queue on the server  
be setup as a raw queue? Is it possible that applying the PPD twice  
will cause problems?

What happens if the PPD on the client and the PPD on the server is  
different?

If I have a PPD on a print queue on a server, does the client somehow  
automatically pick that up?

Kind regards,
Samuel





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