When working with Nginx configuration files in Vim, you might notice inconsistent syntax highlighting behavior. While system files like /etc/nginx/sites-available/default get proper highlighting, custom files like /etc/nginx/sites-available/myapp don't. This happens because Vim doesn't automatically recognize these files as Nginx configurations.

Vim determines filetypes through several methods:

• File extension patterns (*.conf)
• Shebang lines
• Modeline comments
• Content patterns

For Nginx configs, we need to help Vim recognize these files even without standard extensions.

Add this to your ~/.vimrc:

" Detect Nginx config files
au BufNewFile,BufRead /etc/nginx/*,/usr/local/nginx/conf/* if &ft == '' | setfiletype nginx | endif

For a more comprehensive solution that works with any Nginx config location:

" Enhanced Nginx config detection
function! s:DetectNginx()
    if getline(1) =~ '^#.*nginx configuration'
        setfiletype nginx
    endif
endfunction

au BufNewFile,BufRead *.conf,nginx*.conf,*nginx.conf if &ft == '' | call s:DetectNginx() | endif

If you prefer a simpler solution that defaults to conf syntax for unknown files:

" Fallback to conf syntax for unknown filetypes
au BufNewFile,BufRead * if &ft == '' | setfiletype conf | endif

Here's a complete starter .vimrc for working with Nginx configs:

" Basic settings
set nocompatible
syntax on
filetype plugin indent on

" Nginx specific settings
au BufNewFile,BufRead /etc/nginx/*,/usr/local/nginx/conf/* setfiletype nginx
au BufNewFile,BufRead nginx.conf,*nginx*.conf setfiletype nginx

" Fallback for other config files
au BufNewFile,BufRead *.conf if &ft == '' | setfiletype conf | endif

" Display settings
set number
set ruler
set showcmd
set wildmenu

After making changes to your .vimrc, verify the filetype detection works:

1. Open a new Nginx config file: vim /etc/nginx/sites-available/test
2. Check the current filetype: :set ft? (should return nginx)
3. Verify syntax highlighting is working

• Install the vim-nginx plugin for enhanced Nginx syntax support
• Consider adding modelines to your Nginx config files: # vim: set ft=nginx:
• For large configurations, use :syntax sync fromstart if highlighting breaks

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Many sysadmins and developers who work with Nginx configuration files in Vim face this common issue: while default Nginx config files like /etc/nginx/nginx.conf or /etc/nginx/sites-available/default get proper syntax highlighting, newly created files don't. This happens because Vim doesn't automatically recognize these files as Nginx configuration files.

Vim uses several methods to determine filetype:

1. File extension (.conf, .txt, etc.)
2. Shebang line (for scripts)
3. Modeline (special comments in file)
4. Content analysis

For Nginx configs, the most reliable approach is to explicitly tell Vim to treat them as configuration files.

Add these lines to your ~/.vimrc:

" Set filetype for Nginx configs
autocmd BufNewFile,BufRead /etc/nginx/*,/usr/local/nginx/conf/* if &ft == '' | setfiletype nginx | endif

This tells Vim to:

• Apply to both new (BufNewFile) and existing (BufRead) files
• Match files in common Nginx config directories
• Only set filetype if not already detected (if &ft == '')
• Use the nginx filetype (better than just 'conf')

If you prefer file-specific settings, add this as the first or last line in your Nginx config:

# vim: set ft=nginx:

The advantage is it travels with the file, but requires editing each config file.

To check if syntax highlighting is working:

:set filetype?
:set syntax?

Both should return "nginx" for properly configured files.

For a better editing experience, consider adding these to your .vimrc:

" Nginx-specific settings
autocmd FileType nginx setlocal commentstring=#\ %s
autocmd FileType nginx setlocal tabstop=2 shiftwidth=2 expandtab

This sets:

• Proper comment character (# for Nginx)
• 2-space indentation (common Nginx style)

If syntax highlighting still doesn't work:

1. Verify you have Nginx syntax files installed (usually in /usr/share/vim/vimfiles/syntax/nginx.vim)
2. Check for conflicting filetype plugins
3. Try manually setting with :set filetype=nginx