<p>Given a text file <code>file.txt</code> that contains a list of phone numbers (one per line), write a one-liner bash script to print all valid phone numbers.</p>
<p>You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)</p>
<p>You may also assume each line in the text file must not contain leading or trailing white spaces.</p>