POSIX (Portabl Operating System Interface for Unix) Globbing

Cited from the Book "BASH Shell: Essential Programs for Your Survival at Work"

[[:alnum:]] 0-9a-zA-Z
[[:alpha:]] a-zA-Z
[[:blank:]] tab and space
[[:space:]] tab, space and newline
[[:cntrl:]] all control characters
[[:digit:]] 0-9
[[:lower:]] a-z
[[:upper:]] A-Z
[[:print:]] includes the SPACE character, digit, UPPER-case, LOWER-case.
[[:punct:]] all punctuation characters
[[:xdigit:]] 0-9a-fA-F All valid hexadecimal digits