Why won't vim source my .vimrc file

Question

Today, I found my .vimrc didn't take effect. It was ok just hours ago.

When I launched vim with $vim --plugin, :scriptnames echoed nothing: .vimrc file was not sourced. (Note: /etc/vimrc was removed to debug this problem.)

Then I tried to google and found $VIMINIT variable suspicious.

Here is the value of $VIMINIT:

$ echo $VIMINIT
set number

Vim documentation about VIMINIT:

 c. Four places are searched for initializations.  The first that exists
    is used, the others are ignored.  The $MYVIMRC environment variable is
    set to the file that was first found, unless $MYVIMRC was already set.
    -  The environment variable VIMINIT (see also |compatible-default|) (*)
       The value of $VIMINIT is used as an Ex command line.
    -  The user vimrc file(s):
                "$HOME/.vimrc"      (for Unix and OS/2) (*)
                "s:.vimrc"          (for Amiga) (*)
                "home:.vimrc"       (for Amiga) (*)
                "$VIM/.vimrc"       (for OS/2 and Amiga) (*)
                "$HOME/_vimrc"      (for MS-DOS and Win32) (*)
                "$VIM/_vimrc"       (for MS-DOS and Win32) (*)
            Note: For Unix, OS/2 and Amiga, when ".vimrc" does not exist,
            "_vimrc" is also tried, in case an MS-DOS compatible file
            system is used.  For MS-DOS and Win32 ".vimrc" is checked
            after "_vimrc", in case long file names are used.
            Note: For MS-DOS and Win32, "$HOME" is checked first.  If no
            "_vimrc" or ".vimrc" is found there, "$VIM" is tried.
            See |$VIM| for when $VIM is not set.
    -  The environment variable EXINIT.
       The value of $EXINIT is used as an Ex command line.
    -  The user exrc file(s).  Same as for the user vimrc file, but with
       "vimrc" replaced by "exrc".  But only one of ".exrc" and "_exrc" is
       used, depending on the system.  And without the (*)!

I could not understand the vim documentation fully. It seems that $VIMINIT may mess the startup of vim.

Clear $VIMINIT:

$ VIMINIT=
$ echo $VIMINIT

Problem still exist.

Answer 1

Expanding on @mMontu's answer; Vim hunts for initialization in order of that list till it finds one. Since the $VIMINIT variable take precedent to the .vimrc file, it satisfies the search and any other option after that is ignored.

The reason it still didn't work after:

$ VIMINIT=
$ echo $VIMINIT

Is (1) you're setting a local variable not an environment variable. That needs to be exported:

$ export VIMINIT=

(2) this still won't work because VIMINIT is still defined:

$ printenv | grep VIMINIT
VIMINIT=

What needs to happen is removal from the environment all together:

$ unset VIMINIT
$ printenv | grep VIMINIT || echo "Gone"
Gone

(These commands are Bash specific. Change them to suit your preferred shell if needed.)

Answer 2

You probably misunderstood the documentation:

 c. Four places are searched for initializations.  The first that exists
    is used, the others are ignored.

Thus if you are using the VIMINIT, the vimrc won't be loaded.

-  The environment variable VIMINIT (see also |compatible-default|) (*)
   The value of $VIMINIT is used as an Ex command line.

You are setting $VIMINIT to an Ex command, set number, which is OK according to the docs. But if prefer a vimrc, you should include set number on that file instead of using $VIMINIT. You mentioned that you set it to empty and your vimrc was still not loaded, but you actually should unset the variable.