Ruby Ebook [EN - FR]
I tryed to learn ruby to develop msf exploit but I don't find good ebook for that.
Can u help me ?

(I'm belgium so a french ebook can be better)
When you say "develop msf exploit" do you mean that you're looking to create exploit modules for metaploit?

I think maybe you should first look into what kind of exploits you want to develop: For example application security, binary exploitation or other areas? Learn the go-tos around the exploit. Create a POC for this exploit.

Learn ruby. And translate your POC into ruby so you can somehow automate the exploit payload and/or the execution/delivery.
Enchanté. Je ne parle pas le français. But that's really besides the point since the lingua franca of the cyber community is English anyway.

I gather from the content of your post that you're a beginner. Nothing wrong with that, but i would suggest you study up on English before you study up on how to write an exploit that can be employed by the Metasploit Framework. Assuming you're teaching yourself about hacking or more generally, computer science you'll find that nearly all resources with regards to this are written in English.

Secondly, MSF Modules aren't Exploits. Sure they contain exploit code but the Ruby scripts are the means to an end. They're designed so that the actual payload can be configured and effectively deployed/launched by the wider Framework.

Being proficient in Ruby does not an Exploit Developer make. My suggestion to you would be to start off learning a programming language before you dive into stuff like Exploit Dev. C, C++ and Python are good languages to learn, once you know Python getting into Ruby will be easy.

Finally, like Insider alluded to you need figure what manner of systems you want to exploit. The three programming languages i named are just generally good to learn and cover a broad range in terms of their capabilities with regards to Exploit Dev and much, much, more.