Answer by Max Haase for Copying vim colors from older (vim7.4) to vim8

To ensure that your custom syntax highlighting settings persist when you open new files in Vim, you should use the autocmd (autocommand) mechanism in your ~/.vimrc file correctly.The BufWinEnter event is not always sufficient for this purpose. Instead, you should use the Syntax event, which is triggered when syntax highlighting is loaded.

Here is how you can modify your ~/.vimrc to ensure your highlight changes take effect:

" Remove this line if you already have it" au BufWinEnter *.c,*.h highlight Constant ctermfg=9

Add the correct autocommand using the Syntax event:

" Ensure syntax highlighting is enabledsyntax on" Use the Syntax event to apply custom highlightingaugroup my_c_highlightautocmd!autocmd Syntax c highlight Constant ctermfg=9augroup END

Explanation:

syntax on: This ensures that syntax highlighting is enabled.

augroup my_c_highlight: This creates a group for your custom autocommands.Using an augroup helps to manage and clear the autocommands easily.

autocmd!: This clears any existing autocommands in the group to avoid duplicates.

autocmd Syntax c highlight Constant ctermfg=9: This sets the highlight for the Constant group to your desired color (red in this case) whenever a C file's syntax is loaded.

Additional Tips:

If you have multiple highlight groups you want to customize, add additional autocmd lines within the same augroup block.Make sure you have the syntax on command early in your ~/.vimrc to ensure that syntax highlighting is enabled before any customizations are applied.If you're using other plugins or configurations that might affect syntax highlighting, make sure your customizations are loaded after those settings.

With these changes, your custom highlight settings should persist whenever you open C files in Vim.