[LeetCode] 193. Valid Phone Numbers_Easy tag: Bash

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.

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

Code

awk '/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/' file.txt

1) awk '/^$/' file.txt => '^' 表示开始, '$' 表示结束

2) [0-9]表明数字0-9, {3}是三位

3) | 表明或

4) $ 与 $里 '\' 是转译符, 表明会print

5) 其他同理