Or, as a much simpler way (as pointed out in the comment) Ctrl + H v will describe the variable which produces much nicer output.
user-init-file is a variable defined in `C source code'.
Its value is
"/home/.emacs"
Documentation:
File name, including directory, of user's initialization file.
If the file loaded had extension `.elc', and the corresponding source
file
exists, this variable contains the name of source file, suitable for use
by functions like custom-save-all' which edit the init
file.
While Emacs loads and evaluates the init file, value is the real name
of the file, regardless of whether or not it has the .elc' extension.
This way is much more verbose. Start up emacs and in your Lisp evaluation buffer type
user-init-file
And press Ctrl+J to evaluate. This will print out where your init file is
user-init-file
"/home/.emacs"