리눅스 쉘 스크립트 학습 - 정규 표현식 - 기본 연습

기본 연습 - 정규 표현식 연습 사이트
https://regexr.com/38bd56

정규 표현식(Regular Expression)

• 문자열을 검색하거나, 치환할 목적으로 고안된 특수한 문자열

[]

• [] : Character set. Match any character in the set.
  

• 다음과 같이 범위로 지정할 수도 있다.
  
  

^

• set안에 쓰이면, not의 의미를 갖는다.
• ^ : Negated set. Match any character that is not in the set.
  

\w, \W

• \w : Word. Matches any word character (alphanumeric & underscore).
  

• \W : Not word. Matches any character that is not a word character (alphanumeric & underscore).
  

\d, \D

• \d : Digit. Matches any digit character (0-9)
  

• \D : Not digit. Matches any character that is not a digit chracter (0-9)
  

+

• '+' : Quantifier. Match 1 or more of the preceding token.
  

^, +

• ^ : Beginning. Matches the beginning of the string, or the beginning of a line, if the multiline flag is enabled.
• '+' : Quantifier. Match 1 or more of the preceding token.
  

.

• . : Dot. Mtaches any character except line breaks.
  

\s, \S

• \s : whitespace. Matches any whitespace character (spaces, tabs, line breaks)
  

• \S : Not whitespace. Matches any character that is not a whitespace chracter (spaces, tabs, line breaks).
  

\b

• \b : Word boundary. Matches a word boundary position between a word character and non-word character or postion (start /end of string)
• ? : Lazy. Makes the preceding quantifier lazy, causing it to match as few characters as possible