Understanding how "vi" finds its global configuration file

Question

On my Ubuntu OS, I see this in /etc/vim/vimrc.tiny:

$ cat /etc/vim/vimrc.tiny
" Vim configuration file, in effect when invoked as "vi".

Here's the partial output from :version:
system vimrc file: "$VIM/vimrc"

It looks like the VIM environment variable is not defined - echo $VIM doesn't show anything.

So how does vi know to read /etc/vim/vimrc.tiny?

Answer 1

This is not a answer to your question, but a follow up on you comment:

From the above methods, I found $VIM to be /usr/share/vim. So following the :version output, I would think that the system vimrc file is /usr/share/vim/vimrc. However, $ ll /usr/share/vim/vimrc shows it's point to /usr/share/vim/vimrc -> /etc/vim/vimrc, not /etc/vim/vimrc.tiny, and there is no mention of .tiny in /etc/vim/vimrc. So it's not still unclear how the .tiny file is used.

---

You have /etc/vim/vimrc and /etc/vim/vimrc.tiny, because you installed multiple vim-related packages on Ubuntu.

• /etc/vim/vimrc.tiny is from the package "vim-tiny".
• /etc/vim/vimrc is from the package "vim-common"

In a default setup of Ubuntu only "vim-tiny" is installed. This is a small Vim build with limited features (e.g. no syntax highlighting). This package also created the file /usr/share/vim/vimrc as a symbolic link to /etc/vim/vimrc.tiny.

Later on a "bigger" Vim package was installed, like "gvim". This has a dependency on "vim-common". The package "vim-common" contains all the runtime files (syntax highlighting etc). This package also creates the file /usr/share/vim/vimrc, but this time as a symbolic link to /etc/vim/vimrc.

So: The file /etc/vim/vimrc.tiny is from the package "vim-tiny" and is not used anymore. The package is still installed and you can call the executable with

$ vim.tiny

To see all installed vim-related packages execute

$ dpkg -l \*vim\*

Answer 2

Have a look at :h VIMINIT there is a list of places vim looks for a config, and it will use the first one found:

Most used are the user vimrc files:

The user vimrc file(s):

• "$HOME/.vimrc" (for Unix and OS/2) (*)
• "$HOME/.vim/vimrc" (for Unix and OS/2) (*)
• "s:.vimrc" (for Amiga) (*)
• "home:.vimrc" (for Amiga) (*)
• "home:vimfiles:vimrc" (for Amiga) (*)
• "$VIM/.vimrc" (for OS/2 and Amiga) (*)
• "$HOME/_vimrc" (for MS-DOS and Win32) (*)
• "$HOME/vimfiles/vimrc" (for MS-DOS and Win32) (*)
• "$VIM/_vimrc" (for MS-DOS and Win32) (*)

But there is also a backup and systemwide files. Have a look at the help since it is somewhat different depending on version,