Regular Expressions (Regex) Character Classes Cheat Sheet

POSIX Character Classes for Regular Expressions & their meanings

Character Class	Meaning
[:alpha:]	Any letter, `[A-Za-z]`
[:upper:]	Any uppercase letter, `[A-Z]`
[:lower:]	Any lowercase letter, `[a-z]`
[:digit:]	Any digit, `[0-9]`
[:alnum:]	Any alphanumeric character, `[A-Za-z0-9]`
[:xdigit:]	Any hexadecimal digit, `[0-9A-Fa-f]`
[:space:]	A tab, new line, vertical tab, form feed, carriage return, or space
[:blank:]	A space or a tab.
[:print:]	Any printable character
[:punct:]	Any punctuation character: `! ' # S % & ' ( ) * + , - . / : ; < = > ? @ [ / ] ^ _ { \| } ~`
[:graph:]	Any character defined as a printable character except those defined as part of the space character class
[:word:]	Continuous string of alphanumeric characters and underscores.
[:ascii:]	ASCII characters, in the range: 0-127
[:cntrl:]	Any character not part of the character classes: `[:upper:], [:lower:], [:alpha:], [:digit:], [:punct:], [:graph:], [:print:], [:xdigit:]`