Not reading ~/.vimrc

Once you've loaded vim, :scriptnames will tell you exactly what Vim read.

For me, it starts like this:

  1: /Applications/MacVim.app/Contents/Resources/vim/vimrc
  2: ~/.vimrc
  3: /Applications/MacVim.app/Contents/Resources/vim/runtime/syntax/syntax.vim
  4: /Applications/MacVim.app/Contents/Resources/vim/runtime/syntax/synload.vim
  5: /Applications/MacVim.app/Contents/Resources/vim/runtime/syntax/syncolor.vim

IF you want to check where a particular setting is being set, use "verbose set". For example, :verbose set background tells me:

  background=light
        Last set from ~/.vimrc

so I know that my setting in ~/.vimrc is being read, and that none of the later files is clobbering it.

if you're on linux and want to know if vim is accessing your ~/.vimrc on startup you can launch it with strace:

strace -o vim_strace vim

then quit vim. Open the vim_strace file and search for "vimrc" in the file. you should find a line like that

stat64("/home/youruser/.vimrc", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0

which mean that at least vim sees the file.