Regular Expression, Regular Expression

Regular Expression, Regular Expression

Basic Regular Expression

First line positioning character ^

Ls | grep ^ files starting with abc

Line tail locator $

Match a single character.

. Represents any character, except for line breaks

Qualifier *

* Represents the first 0-n characters

Character Set matching []

[Abc] indicates that a character is a, B, or c.

Character Set mismatch [^]

[^ Abc] indicates a character not a, B, or c.

Expanded Regular Expression

Qualifier +

The first 1-n characters, a + indicates that there are 1 to n

Qualifier?

The first 0-1 Characters

Vertical bars | and parentheses ()

(Abc | def | ghi) indicates that the value is abc, def, or ghi.

Number of matches {m, n}

(Abc) [1, 2] indicates abc or abcabc

Perl expressions

Number match \ d

Equivalent to [0-9]

Non-digit match \ D

Equivalent to [^ 0-9]

Blank character match \ s

Equivalent to [\ f \ n \ r \ t \ v]

Non-blank character match \ s

Equivalent to [^ \ f \ n \ r \ t \ v]

Example

Start with abc and end with xyz: ^ abc. * xyz $

Not starting with abc:

Does not contain abc: