[\b]

Backspace

\f

Form feed

\n

Line feed

\r

Carriage return

\t

Tab

\v

Vertical tab

\d

Any digit (same as [0-9])

\D

Any nondigit (same as [^0-9])

\w

Any alphanumeric character in upper- or lower-case and underscore (same as [a-zA-Z0-9_])

\W

Any nonalphanumeric or underscore character (same as [^a-zA-Z0-9_])

\s

Any whitespace character (same as [\f\n\r\t\v])

\S

Any nonwhitespace character (same as [^\f\n\r\t\v])

[:alnum:]

Any letter or digit, (same as [a-zA-Z0-9])

[:alpha:]

Any letter (same as [a-zA-Z])

[:blank:]

Space or tab (same as [\t ])

[:cntrl:]

ASCII control characters (ASCII 0 through 31 and 127)

[:digit:]

Any digit (same as [0-9])

[:graph:]

Same as [:print:] but excludes space

[:lower:]

Any lowercase letter (same as [a-z])

[:print:]

Any printable character

[:punct:]

Any character that is neither in [:alnum:] nor [:cntrl:]

[:space:]

Any whitespace character including space (same as [\f\n\r\t\v ])

[:upper:]

Any uppercase letter (same as [A-Z])

[digit:]

Any hexadecimal digit (same as [a-fA-F0-9])