Shell Note 4

Metacharacters and descriptions commonly used in regular expressions

Metacharacters	Symbol name	Description
\	Back slash	Escape character
|	Pipeline	Or
[]	Square brackets	Represents one of the characters in a specified range
[^]	Square brackets + Caret	Match characters that are not within a specified group
()	Parentheses	You can combine regular characters and metacharacters a character or an expression
{}	Curly Braces	Specify a minimum or maximum number of matches for a leading expression, for example, a{3,4} will match "AAA" and "AAAA"
^	Insert character	Used to specify the header of the matching string, also known as the line header
$	Dollar symbol	Used to specify the tail of the matched string, also known as the end of line locator
*	Asterisk	Matches 0 or more leading expressions, a * matches a string consisting of 0~n "a"
？	Question mark	Matches 0 or 1 leading expressions, a? Will match "a" or "AA"
\<	Backslash + Less Sign	A word head locator, such as "\<ABC", represents all lines that contain words beginning with ABC
\>	Backslash + greater than sign	The ending locator, such as "\>ABC", represents all lines that contain words ending in ABC
.	Point number	Match any one character
-	Minus sign	Used to indicate a range of characters, such as [A-z] representing characters from ' a ' to ' Z '

Shell Note 4