#!/bin/sh
var=","
gn=8

#init 
tn=`expr 10 + $gn`
for k in $(seq 10 $tn);do
 var=$var$k','
 eval "gvar$k"="m$k"
done

#change it
var=${var/14/00}

#get it
for k in $(seq 0 $gn);do
case ${var:`expr 3 \* $k`:4} in
        ',00,')
        echo "ok $gn "
        break
;;
        *)
        echo ${var:`expr 3 \* $k`:4} 
;;
esac
done
lst="gvar"`expr 10 + $k`
echo "last  $k $lst" 
var1=`eval echo '$'$lst`
echo $var1

echo ${var1:0:1}
echo ${var1/2/0}