Crop PDF files with Ghostscript
Normally, with the following command and justifications on the CropBox parameters, it should work.
gs -o cropped.pdf -sDEVICE=pdfwrite -dFirstPage=150 -dLastPage=180 -c "[/CropBox [100 100 500 500]" -f in.pdf
in case the pdf file has no CropBox property, which can be checked with
pdfinfo in.pdf
then the following command can be used instead
gs -o cropped.pdf -sDEVICE=pdfwrite -dFirstPage=150 -dLastPage=180 -dDEVICEWIDTHPOINTS=200 -dDEVICEHEIGHTPOINTS=250 -dFIXEDMEDIA -c "<</PageOffset [-21 -32]>> setpagedevice" -f in.pdf