POSIX regular expression cheatsheet

Tags:

Alphabetic [:alpha:]
Alphanumeric [:alnum:]
Control characters [:cntrl:]
Hex numbers [:xdigit:]
Lowercase [:lower:]
Nonespace characters [:graph:]
Numbers [:digit:]
Printable [:print:]
Punctuation [:punct:]
Tab or space [:blank:]
Uppercase [:upper:]
White space [:space:]
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