브라켓 expression

POSIX Bracket Expressions

POSIX bracket expressions are a special kind of character classes. POSIX bracket expressions match one character out of a set of characters, just like regular character classes.

Standard POSIX

[:alnum:](/everjs78/study/wiki/:alnum:)   Alphanumeric characters
[:alpha:](/everjs78/study/wiki/:alpha:)   Alphabetic characters
[:blank:](/everjs78/study/wiki/:blank:)   Space and tab
[:cntrl:](/everjs78/study/wiki/:cntrl:)   Control characters
[:digit:](/everjs78/study/wiki/:digit:)   Digits
[:graph:](/everjs78/study/wiki/:graph:)   Visible characters (anything except spaces and control characters)
[:lower:](/everjs78/study/wiki/:lower:)   Lowercase letters
[:print:](/everjs78/study/wiki/:print:)   Visible characters and spaces (anything except control characters)
[:punct:](/everjs78/study/wiki/:punct:)   Punctuation (and symbols).
[:space:](/everjs78/study/wiki/:space:)   All whitespace characters, including line breaks
[:upper:](/everjs78/study/wiki/:upper:)   Uppercase letters
[:xdigit:](/everjs78/study/wiki/:xdigit:)  Hexadecimal digits

None Standards
[:ascii:](/everjs78/study/wiki/:ascii:)   ASCII characters
[:word:](/everjs78/study/wiki/:word:)    Word characters (letters, numbers and underscores)

legacy syntax (can someone find reference to these?)
[:<:](/everjs78/study/wiki/:<:)       Start of Word 
[:>:](/everjs78/study/wiki/:>:)       End of Word