loop issue

function ext
{
echo "THANKS & WELCOME BACK"
}
function upc
{
echo "TO EXPORT UPROC GIVE UPROC NAME PER LINE IN THE input.txt and PRESS Y"
echo "TO GO BACK PRESS 99"
read parm0
if [ "$parm0" == "99" ];
then
start
elif [ "$parm0" == "Y" ];
then
for i in `cat input.txt` ; do
echo $i
$UXEXE/uxext upr upr=$i output=$i.upr APP
echo "$output UPROC exported"
done
fi
}
function ses
{
echo "TO EXPORT SESSION GIVE SESSION NAME PER LINE IN THE input.txt and PRESS Y"
echo "TO GO BACK PRESS 99"
read parm0
if [ "$parm0" == "99" ];
then
start
elif [ "$parm0" == "Y" ];
then
for i in `cat input.txt` ; do
echo $i
$UXEXE/uxext ses ses=$i output=$i.ses APP
echo "$output SESSION exported"
done
fi
}
function pln
{
echo "TO EXPORT PLANNIFICATION GIVE PLANNIFICATION NAME IN THE input.txt and Management unit in the mu.txt and PRESS Y EX:BDRMX100"
echo "TO GO BACK PRESS 99"
read parm0
a=0
b=0
if [ "$parm0" == "99" ];
then
start
elif [ "$parm0" == "Y" ];
then
for i in `cat input.txt` ; do
a=`expr $a + 1`
for j in `cat mnu.txt` ; do
b=`expr $b + 1`
if [ $a == $b ];
then
$UXEXE/uxext tsk ses=$i vses=* upr=* model mu=$j `output=$j_$i.pnf` APP >ot.txt
echo "$output PLANNIFICATION exported"
fi
done
done
fi
}
function start
{
echo "FOR UPROC EXPORT PRESS 1"
echo "FOR SESSION EXPORT PRESS 2"
echo "FOR PLANNIFICATION EXPORT PRESS 3"
echo "TO EXIT PRESS 99"
read option1
if [ "$option1" == "1" ];
then
upc
elif [ "$option1" == "2" ];
then
ses
elif [ "$option1" == "3" ];
then
pln
elif [ "$option1" == "99" ];
then
ext
fi
}
echo " *****WELCOME****** "
echo " PLEASE PRESS 0 TO SERVE YOUR REQUEST "
echo " TO EXIT PRESS 99 "
read option
if [ "$option" == "99" ];
then
ext
elif [ "option" == "0" ];
echo "In start function"
then
start
fi

****************
hello folks
the above red funtionality is like i have to pass 2 paramerters which is passed by the the 2 files input.txt and mnu.txt

my req is that it must take the first line from the input.txt(first input) and first line from mnu.txt(first input) and must proceed / again 2 input from input.txt and mnu .............

can you please correct me how can i implement this incode or where i am wrong
my exixting functionality is extracting the output but in some unknown file

please help