Regular Expression

Option	Description
.	The period (.) matches any single character.
?	The preceding item is optional and will be matched at most once.
*	The preceding item will be matched zero or more times.
+	The preceding item will be matched one or more times.
{n}	The preceding item is matched exactly n times.
{n,}	The preceding item is matched n or more times.
{,m}	The preceding item is matched at most m times.
{n,m}	The preceding item is matched at least n times, but not more than m times.
[:alnum:]	Alphanumeric characters: ‘[:alpha:]’ and ‘[:digit:]’; in the ‘C’ locale and ASCII character encoding, this is the same as ‘[0-9A-Za-z]’.
[:alpha:]	Alphabetic characters: ‘[:lower:]’ and ‘[:upper:]’; in the ‘C’ locale and ASCII character encoding, this is the same as ‘[A-Za-z]’.
[:blank:]	Blank characters: space and tab.
[:cntrl:]	Control characters. In ASCII, these characters have octal codes 000 through 037, and 177 (DEL). In other character sets, these are the equivalent characters, if any.
[:digit:]	Digits: 0 1 2 3 4 5 6 7 8 9.
[:graph:]	Graphical characters: ‘[:alnum:]’ and ‘[:punct:]’.
[:lower:]	Lower-case letters; in the ‘C’ locale and ASCII character encoding, this is a b c d e f g h i j k l m n o p q r s t u v w x y z.
[:print:]	Printable characters: ‘[:alnum:]’, ‘[:punct:]’, and space.
[:punct:]	Punctuation characters; in the ‘C’ locale and ASCII character encoding, this is! " # $ % & ’ ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ’ {
[:space:]	Space characters: in the ‘C’ locale, this is tab, newline, vertical tab, form feed,carriage return, and space.
[:upper:]	Upper-case letters: in the ‘C’ locale and ASCII character encoding, this is A B C D E F G H I J K L M N O P Q R S T U V W X Y Z.
[:xdigit:]	Hexadecimal digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f.
	Match the empty string at the edge of a word.
\B	Match the empty string provided it is not at the edge of a word.
<	Match the empty string at the beginning of word.
>	Match the empty string at the end of word.
\w	Match word constituent. Synonym for ‘[_[:alnum:]]’.
\W	Match non-word constituent. Synonym for ‘[^_[:alnum:]]’.
\s	Match white space. Synonym for ‘[[:space:]]’.
\S	Match non-whitespace. Synonym for ‘[^[:space:]]’.