hi experts,
Where will I be able to find the whole man of unix commands in Web(the official documentation)?
How many commands are there in total in Unix?
since you didn't ask which version, google "posix"
Another good and reasonably well-defined set would be the FreeBSD manuals, which are conveniently all over Google as well.
I know this probably isn't what you are looking for but I always found this useful for unix command help.
Unix and Linux commands, information and help