grep « String « Ruby

1.Regular Expressions
2.match the first line just by using a word in the pattern
3.a pair of square brackets ([]) matches any character in the brackets
4.match alternate forms of a pattern using the pipe character (|)
5.Grouping uses parentheses to group a subexpression, like this one that contains an alternation
6.Anchors anchor a pattern to the beginning (^) or end ($) of a line
7.\d represents a digit; it is the same as using [0-9].
8.Similar to $, the shortcut \z matches the end of a string, not a line
9.Find out the phone number

10.? is a repetition operator
11.The plus sign (+) operator indicates one or more of the previous pattern
12.Braces ({}) specifies the exact number of digits, such as \d{3} or \d{4}