As anonymonk puts it, "loop":

while( $run ) {

    my $newline = $objPort->lookfor;

   if ( $newline ne '' ) {
        print $newline;
        $run = 0 
             if $newline =~ /reason to stop/;
    }
   
}
[download]

Another possibility is that your are_match() settings are matching "\n" and leaving "\r" on your lines, so when then print to the terminal, each line of text is overwritten. Try directing the output to file. That should show you if this is happening.

Also, be careful with "\n", because it can mean "\r\n" in some windows perl environments. You should consider using the hexadecimal escapes "\x0A" and "\x0D", as no magic happens with them.

Update: Fixed escape sequences. Thanks to BrowserUk.