Character classes in the C shell

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You can use character classes to match file names within a range indication.

The following format instructs the system to match any single character belonging to the specified class: 
[:charclass:]

The following classes correspond to ctype subroutines:

Character Class Definition
alnum Alphanumeric characters
alpha Uppercase and lowercase letters
cntrl Control characters
digit Digits
graph Graphic characters
lower Lowercase letters
print Printable characters
punct Punctuation character
space Space, horizontal tab, carriage return, newline, vertical tab, or form-feed character
upper Uppercase characters
xdigit Hexadecimal digits
Suppose that you are in a directory containing the following files: 
a aa aax Alice b bb c cc
Type the following command at a C shell prompt: 
     ls [:lower:]
The C shell lists all file names that begin with lowercase characters: 
a aa aax b bb c cc

For more information about character class expressions, see the ed command.