best cheat sheet ever

Unified access to the best community-driven cheat sheets repositories of the world.
Let's imagine for a moment that there is such a thing as an ideal cheat sheet. What should it look like? What features should it have?

• Concise — It should only contain the things you need, and nothing else.
  
• Fast — It should be possible to use it instantly.
  
• Comprehensive — It should contain answers to every possible question.
  
• Universal — It should be available everywhere, anytime, without any preparations.
  
• Unobtrusive — It should not distract you from your main task.
  
• Tutoring — It should help you to learn the subject.
  
• Inconspicuous — It should be possible to use it completely unnoticed.
  

 

• Has a simple curl/browser/editor interface.
  
• Covers 56 programming languages, several DBMSes, and more than 1000 most important UNIX/Linux commands.
  
• Provides access to the best community-driven cheat sheets repositories in the world, on par with StackOverflow.
  
• Available everywhere, no installation is needed, but can be installed for offline usage.
  
• Ultrafast, returns answers within 100 ms, as a rule.
  
• Has a convenient command-line client, 
  Code:

  cht.sh ,
  that is very advantageous and helpful, though not mandatory.
  
• Can be used directly from code editors, without opening a browser and not switching your mental context.
  
• Supports a special stealth mode where it can be used fully invisibly without ever touching a key and making sounds.
  

I personally use this tool on my Linux VM and I find it extremely useful for learning


if your new to Linux I suggest u look at this