In example, when working on a Vi editor, There are many buffers where I can recover the info just typing u command. Is there anything similar in unix?
As far as I know, not by default. Here at our university we use unix and if I delete a file then it's gone, all I can do is ask the system admins to restore it from backup if it there is one (they backup once a day here). Better ask your admin what is available for the system you use.
Could you please show me the link where you take that sentences off?
Like I said, it's from the manpage. If you want to see documentation for a command, just type "man command" in the command line, e.g., "man bash" (without the quotes, of course).