Learn Ruby Language and Be an exploit coder-12

Libraries

Hello buddies...

Take a look on this code...

• require 'open-uri'

• 
  

• open("http://writingexploit.blogspot.com") do |f|

•   f.each_line {|line| p line}

•   puts f.base_uri         # <URI::HTTP:0x40e6ef2 URL:http://writingexploit.blogspot.com/>

•   puts f.content_type     # "text/html"

•   puts f.charset          # "iso-8859-1"

•   puts f.content_encoding # []

•   puts f.last_modified    # Thu Dec 05 02:45:02 UTC 2002

• end

On line 1 we have what's called a "require". This is how you add features to your script from the Ruby feature set or other sources (e.g., Ruby Gems, stuff you wrote yourself). Rather than give you all the features at once, Ruby asks you to say what you plan to use. This keeps your programs small, but it also acts as documentation for other programmers who read your code later.

Hold Up! Features Have Another Name

I call them "features" here (these little things you require to make your Ruby program do more) but nobody else calls them features. I just used that name because I needed to trick you into learning what they are without jargon. Before you can continue, you need to learn their real name: libraries.

From now on we will be calling these "features" that we require libraries. I'll say things like, "You want to require the open-uri library." They are also called "modules" by other programmers, but let's just stick with libraries.

Extra Credit

Research the difference between require and include. How are they different?
Can you require a script that doesn't contain a library specifically?
Figure out which directories on your system Ruby will look in to find the libraries you require.