Hai, Try this simple

undef $/;
open(IN, "D:\\temp.log");
$str = <IN>;
print $str;
close(IN);
$str =~ s#<b>#*<b>#gsi;
$str =~ s#</b>#</b>*#gsi;
open(OUT, "> D:\\temp.log");
print OUT $str;
close(OUT);
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Regards,
Gubendran.L