Shell Regular Expression

One. grep

grep parameters:

- n: Show Line Numbers

- o: Show only matching content

- Q: silent mode, no output, you have to use $? To determine the success of the execution, that is, there is no filtering to the desired content

- L: If the match succeeds, only the file name is printed, the failure is not printed, usually-rl together,grep-rl ' root '/etc

-A: If the match is successful, print the matching line together with the N rows after the period

- b: If the match succeeds, the matching row and the first n rows of the period are printed together

- C: If the match succeeds, print the matching row and the N rows before and after the period

--color

- C: If the match succeeds, the number of rows to match is printed

- e: equals grep, extended

-I: Ignore case

- v: inverse, mismatch

- w: match word

[Email protected] ~123[[email protected]"root"  123 [[email protected]"root"123

Two. Regular introduction

^ beginning of the line

$ End of line

. Any single character other than the line break

* Leading characters of the Spirit song or multiple

. * All characters

[] any character within a character group

[^] reverse each character within a character group (does not match each character in a group of characters)

^[^] lines that begin with characters within a non-character group

[A-z] lowercase Letter

[A-z] capital letters

[A-z] uppercase and lowercase letters

[0-9] number

\< words are usually separated by spaces or special characters, and successive strings are treated as words.

\> Word Tail

Shell Regular Expression