Mastering the Nmap Scripting Engine

String handling

Lua's string library supports a lot of handy string operations. Strings will obviously be used frequently when writing NSE scripts since they are perfect for representing byte sequences. Let's review the most common functions and operators used in string handling.

Character classes

Character classes are special operators used in patterns. We will need them when matching or subtracting substrings, so keep them in mind when we review patterns and string operations:

Character classes	Represents
.	All characters
%a	Letters
%c	Control characters
%d	Digits
%l	Lowercase letters
%p	Punctuation characters
%s	Space characters
%u	Uppercase letters
%w	Alphanumeric characters
%x	Hexadecimal digits
%z	Null (0x90)

Magic characters ...