193. Valid Phone Numbers

Posted 2021-02-03 bernieloveslife

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
[phone]

Your script should output the following valid phone numbers:

987-123-4567
[phone]

# Read from the file file.txt and output all valid phone numbers to stdout.
egrep ‘(^([0-9]{3}) |^[0-9]{3}-)[0-9]{3}-[0-9]{4}$‘ file.txt