Vim – How to Make Settings Computer-Dependent in .vimrc

If you're editing it, you can reload it with:

:so %

% stands for current file name (see :h current-file) and :so is short for :source, which reads the content of the specified file and treats it as Vim code.

In general, to re-load the currently active .vimrc, use the following (see Daily Vim):

:so $MYVIMRC

From the Vim man page:

-u {vimrc}

Use the commands in the file {vimrc} for initializations. All the other
initializations are skipped. Use this to edit a special kind of files.
It can also be used to skip all initializations by giving the name "NONE".
See ":help initialization" within vim for more details.

If you still want your ~/.vimrc to be processed, try this:

vim -u ~/.vimrc

Add the following line to ~/.bashrc (or your shell's equivalent file if not bash) to have the -u switch added automatically:

alias vim="vim -u ~/.vimrc"

You won't be able to add something to ~/.vimrc to prevent /etc/vimrc from being read, because the system file is processed before your user file (see ":help init", section 3, "Execute Ex commands, from environment variables and/or files").