Shell Programming and Scripting

#!/bin/ksh

POS1=116 ; VAL1=441
POS2=130 ; VAL2=442

VAL_LEN=3

XPOS1=$((POS1 + $VAL_LEN - 1))
XPOS2=$((POS2 + $VAL_LEN - 1))

echo POS1=$POS1,XPOS1=$XPOS1
echo POS2=$POS2,XPOS2=$XPOS2

infile=$1
outfile=$2

NBL=$(wc -l $infile)
NBC=0

while [ $NBC -lt $NBL ]
do
        (( NBC = NBC + 1 ))

        xval1=$(head -$NBC $infile | tail -1 | cut -b$POS1-$XPOS1)
        xval2=$(head -$NBC $infile | tail -1 | cut -b$POS2-$XPOS2)

        if [ "$xval2" = "$VAL2" ]
        then
                if [ "$xval1" = "$VAL1" ]
                then
                        head -$NBC $infile | tail -1 >> $outfile
                else
                        # Must replace with $VAL1

                        echo "Must replace on line "$NBC

                        k1=$(head -$NBC $infile | tail -1 | sed 's/ /#/g')
                        (( ZPOS1 = POS1 - 1 ))
                        k2=$(echo $k1 | cut -b1-$ZPOS1)
                        (( ZPOS1 = XPOS1 + 1 ))
                        k3=$(echo $k1 | cut -b$ZPOS1-)
                        
                        echo "${k2}${VAL1}${k3}" | sed 's/#/ /g' >> $outfile
                fi
        else
                head -$NBC $infile | tail -1 >> $outfile
        fi
done