The following table list all valid values that can be used in a character class expression [:class:]:
| Name | Description |
|---|
| alnum | Any alpha-numeric character. |
| alpha | Any alphabetic character. |
| blank | Any whitespace character that is not a line separator. |
| cntrl | Any control character. |
| d | Any decimal digit |
| digit | Any decimal digit. |
| graph | Any graphical character. |
| l | Any lower case character. |
| lower | Any lower case character. |
| print | Any printable character. |
| punct | Any punctuation character. |
| s | Any whitespace character. |
| space | Any whitespace character. |
| unicode | Any extended character whose code point is above 255 in value. |
| u | Any upper case character. |
| upper | Any upper case character. |
| w | Any word character (alphanumeric characters plus the underscore). |
| word | Any word character (alphanumeric characters plus the underscore). |
| xdigit | Any hexadecimal digit character. |
| EXAMPLE | [[:upper:]] will match any upper case character.
^[[:lower:]].* will match any string that starts with a lower case character. |
|---|
