[:alnum:]: Alphanumeric characters, same as [a-zA-Z0-9][:alpha:]: Alphabetic characters, same as [a-zA-Z][:blank:]: Space or tab characters, same as [ \t][:cntrl:]: Control characters[:digit:]: Numeric characters, same as [0-9][:graph:]: Visible characters (i.e., not space, control, or delete)[:lower:]: Lowercase letters, same as [a-z][:xdigit:]: Hexadecimal digits, same as [0-9A-Fa-f]- [:space:]: Whitespace characters, same as [ \t\n\x0B\f\r][:upper:]: Uppercase letters, same as [A-Z][:punct:]: Punctuation characters, same as !"#$%&'()*+,-./:;<=>?@[\]^_{ |
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[:print:]: Visible characters and space, same as [:graph:] + [ ]