RE: line number at the beginning of the line

[Drew Adams]

    is there any command or variable in emacs, that it will displays the
    number for every line at the beginning of it???
    
Don't google first. Try Emacs Wiki first: 
http://www.emacswiki.org/cgi-bin/wiki/Search. You'll find pages like this one: 
http://www.emacswiki.org/cgi-bin/wiki/LineNumbers.

Actually, try Emacs itself first, for help. Unfortunately, vanilla Emacs can't 
display line numbers at the beginnings of lines, so Info and M-x apropos won't 
get you far on this one.