reorder4booklet2 (shuffle for 2up impose) USABLE IN PIPES

#!/bin/sh
#simple script to get range of pages to use for reordering pages in a pdf and passing as argument to another pdf editing program (like pdftk), in order to impose as booklet with another program like Multivalent Impose tool. version intended to be usable in pipes
#
#usage: reorder4booklet2 number of pages
#
#number of pages must be a multiple of 4 or script will exit
#
#example: pdftk file.pdf cat `reorder4booklet2 40` output outputfile.pdf
#
#and *reorder4booklet2 40* will produce this output range: 40 1  2 39 38 3  4 37 36 5  6 35 34 7  8 33 32 9  10 31 30 11  12 29 28 13  14 27 26 15  16 25 24 17  18 23 22 19  20 21
#
#!/bin/sh
tot=$1
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