Problem

Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.

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)

You may also assume each line in the text file must not contain leading or trailing white spaces.

For example, assume that file.txt has the following content:

987-123-4567
123 456 7890
(123) 456-7890

Your script should output the following valid phone numbers:

987-123-4567
(123) 456-7890

即從檔案中找到合法的電話號碼。又進入bash題區了。

Bash

grep -P '^(\d{3}-|\(\d{3}\) )\d{3}-\d{4}$' file.txt

分析

沒啥可說的，正則題而已。唯一需要注意的是，這裡用的是\d ，所以需要-P支援。