currently I am using
gs -sPAPERSIZE=a4 -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite sOutputFile=combined.pdf input1.pdf input2.pdf input3.pdf
for combining my pdf files, however I have noticed, that combined.pdf according to evince's document properties has a paper size of "231 x 314 mm". Is there a way to fix this?
Thanks.