Question

I have a text file on a unix system. The following text file content creates the problem:

good: ok line
vi: bad line
ok: ok line

So if I run: vim test.txt, I get the following error:

"test.txt" 3L, 39C
Error detected while processing modelines:
line    2:
E518: Unknown option: bad
Press ENTER or type command to continue

If I delete my ~/.vimrc, the error disappears. But what is weird is that, even with an empty ~/.vimrc file, the error appears.

I understand that it’s because the line starts with vi: that the error is created, but I don’t understand why or how to fix this.

Answer 1

The vi: bad line line is in a format that Vim recognizes as a modeline, as mentioned in the error message. Modelines allow one to set options within a file.

The reason it isn’t triggered when you don’t have a ~/.vimrc is because Vim requires you have 'nocompatible' set for modelines to be enabled by default, since it is a Vim-specific feature. The existence of ~/.vimrc is enough for Vim to switch from vi-compatible mode to nocompatible, though, which will result in the 'modeline' option also being set.

For future reference, you can easily find help topics in Vim via :help topic<Tab>. In this case, :help modeline<Tab> would have given you a few topics to look into which explain this feature and how to control it.