[Bash] extract pages from a pdf file using gs

#!/bin/bash # extract pages from a big pdf file using gs # Usage: #           pdfselect.sh pdffile startPageNumber endPageNumber #           http://scriptdemo.blogspot.ca function getPDFPages() {    if [ -e $1 ]; then       pdfinfo $1 | grep "Pages" | awk '{print $2}'    else       echo 0;    fi } if [ $# -lt 2 ]; then    sed -n '3,4p' `which pdfselect.sh`    exit fi oriPdf=$1 [ ! -e ${oriPdf} ] && echo "${oriPdf} does not exist! " && exit numPage=`getPDFPages ${oriPdf}` [ ${numPage} -eq 0 ] && "ZERO page is found in ${oriPdf}" && exit sPage=$2 [ ${sPage} -gt ${numPage} ] && ${sPage}=${numPage} if [ $# -eq 2 ]; then    ePage=${sPage} else    ePage=$3; fi [ ${ePage} -gt ${numPage} ] && ${ePage}=${numPage} if [ $# -lt 4 ]; then    outPdf="p${sPage}_${ePage}_${oriPdf}" else    outPdf=$4 fi eval "gs -sDEVICE=pdfwrite -dNOPAUSE -dBATCH -dSAFER -dFirstPage=${sPage} -dLastPage=${ePage} -sOutputFile=${outPdf} ${oriPdf}"