reorder4booklet1 (shuffle for 2up impose) NOT USABLE IN PIPE

#!/bin/sh
#simple script to get range of pages to use for reordering pages in a pdf, in order to impose as booklet with another program like Multivalent Impose tool. Interactive version, not usable in pipes
#
#number of pages must be a multiple of 4 or script will exit
#
echo " enter number of pages"
read tot
if [ $(( $tot % 4 )) -eq 0 ]
    then
tot4="`let DIVISION=$tot/2; echo $DIVISION`"
for ((x=$tot, y=1;x>=$tot4, y<=tot4;x--, y++)); do echo "$x $y "; done | awk '{ print ; getline ; print $2, $1 }' | tr '\n' ' '
    else
echo " $tot is not a multiple of 4"
fi
exit