how could I use different `.vimrc` with `-u` option

Question

I have configured my .vimrc to make my vim work, and then I renamed my .vimrc to be .vimrc2. After that my vim can run as clean mode, but when I run my vim with vim -u .vimrc2, there are errors like this:

E10: \ should be followed by /, ? or &
line   59:
E10: \ should be followed by /, ? or &
line   60:
E10: \ should be followed by /, ? or &
line   61:
E10: \ should be followed by /, ? or &
line   73:
E117: Unknown function: pathogen#infect
E15: Invalid expression: pathogen#infect()

How could I make it work? My .vimrc2 works well if it is renamed to be .vimrc and no -u options are used.

Edit:

my vimrc is here: https://github.com/CoinCheung/learn-coding-notes/blob/master/vim/00-vimrc

Answer 1

Vim will automatically set nocompatible when loading ~/.vimrc or ~/.vim/vimrc. But it's not set automatically when loading a file with the -u option, or using :source.

The solution is to add set nocompatible to the .vimrc2 file, or use the -N flag to set it (vim -N -u .vimrc2).

Personally I think it's always a good idea to add set nocompatible to vimrc files exactly to avoid this confusion, even if it's not strictly needed when loading from the default locations. But some people are dead-set against it 🤷‍