echo Enter main string: read main l1=\`echo $main | wc -c\` l1=\`expr $l1 - 1\` echo Enter sub string: read sub l2=\`echo $sub | wc -c\` l2=\`expr $l2 - 1\` n=1 m=1 pos=0 while [ $n -le $l1 ] do a=\`echo $main | cut -c $n\` b=\`echo $sub | cut -c $m\` if [ $a = $b ] then n=\`expr $n + 1\` m=\`expr $m + 1\` pos=\`expr $n - $l2\` r=\`expr $m - 1\` if [ $r -eq $l2 ] then break fi else pos=0 m=1 n=\`expr $n + 1\` fi done echo Position of sub string in main string is $pos