How to see rastertopclx filter stderr log?

[livmorexu]

hello

How to see rastertopclx filter stderr log?

such as:
fprintf(stderr, "DEBUG: StartPage...\n");
fprintf(stderr, "DEBUG: MediaClass = "%s"\n", header->MediaClass);
fprintf(stderr, "DEBUG: MediaColor = "%s"\n", header->MediaColor);
fprintf(stderr, "DEBUG: MediaType = "%s"\n", header->MediaType);
fprintf(stderr, "DEBUG: OutputType = "%s"\n", header->OutputType);

[livmorexu]

when at the termial input [lp test.pdf] , how to see rastertopclx filter stderr log?