https://leetcode.com/problems/valid-phone-numbers/
# Read from the file file.txt and output all valid phone numbers to stdout.
awk ‘/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/{print $0}‘ file.txt
原文：http://blog.csdn.net/qinchaowhut/article/details/46841319