String 

A string is a sequence of characters enclosed by double quotes. A string may also contain double quotes, but the quotes must be immediately preceded by a backslash. A backslash is represented in a string as \\. Quotes are not required if a string begins with a letter, and contains only letters, numbers, dashes (-), and underscores (_). For example, a string defining a network interface such as hme0 or eth0 does not require quotes as it contains only letters and numbers. However a string defining an IP address contains periods and requires quotes, such as: 192.168.100.1  

Integer 

Signed integer constants are a sequence of digits from 0 to 9. They may be preceded by a dash, and are interpreted in base 10. Integers cannot exceed the value of a 32-bit signed integer: 21471183247. 

Boolean 

A boolean is an integer, the possible values of which are 0 (false) and 1 (true).