Only copying one file is not enough, otherwise you have no chance
for giving additional parameters like colorspace, orientation,
resolution, etc, etc, etc. The application would have to handle all
this by itself and would require more detailed information about the
printer (which would tie the job to one specific printer).
How about simply:
$ echo "print <printing-options> <printer-options>" > /printers/ctl
$ cat myfile > /printers/data
Skipping either the printing/printer options while writing to ctl
will result in default options being applied.
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Anant