PPD and filter

[Anonymous]

Hi sir,

I want to know the basic working principle with the PPD file.

Let us take I have a PPD file with many paper sizes including letter paper size
and many resolutions including 180x180 DPI and additional unique feature called
WithFormFeed and WithoutFormFeed.

The printer driver will list all those features once it gets installed. Once
driver has been installed, I can take the test page or print any document from
the editor using any paper size or resolution or available feature. For example
I will select letter,180x180 DPI with FormFeed feature and print the document.

But i can't understand how raster filter will come to know that I have selected
this paper size,resolution or any feature.

I have seen getenv function which calls with the PPD parameter in the
rastertoepson filter code.
Is there any PPD environment variable created during the printing process and
will be deleted after the completion of printing.

Because if i use echo $PPD in the command line,it will not show any environment
variable named PPD.

I think, this is one of the important details, every printer driver development
aspirant should know.

Any tips,help greatly apprecieated.

Thanks in advance.

Regards
Suresh