Can you provide your perl script please? We could better help you. Also, be sure to wrap your code with the "code" tags for readability.

I see double quotes in the example you provide. Make sure you are being careful with mixed quotes. If you wrapped the entire UNIX command in single quotes, then variable expansion will not work (i.e. $valu will be treated as a string, not as a variable). If you wrapped the UNIX command with double quotes, it will conflict with the double quotes inside the string.

Once you provide your perl script, we can help further.