$search_text = $ARGV[0];
$filename = $ARGV[1];

$capital_search_text = uc($search_text);

open FILE,"<$filename" or die "Cannot read the file $filename: $!\n";

while ($line = <FILE>)
{
    if ($line =~ m/$search_text/)
    {
        $line =~ s/$search_text/**$capital_search_text**/ig;

        print $line;
    }
}