Or save yourself $15 and just make a function to something that you probably already have on your Linux system:

shrink_pdf () 
{ 
    if [[ $# -ne 2 ]]; then
        echo 'Usage:  shrink_pdf <input file> <output_file>' 1>&2;
        echo '                   make sure to enclose file name in quotes' 1>&2;
        echo '                   if it has spaces' 1>&2;
        return;
    fi;
    gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile="$2" "$1"
}

Change options as you want, and run it like:

shrink_pdf Original.pdf Compressed.pdf