How Does Vim Auto-Indent Handle Mixed Tabs And Spaces?

If you're fiddling with Vim's indentation and want precise control, the trio I reach for is :set shiftwidth, :set tabstop, and :set softtabstop. shiftwidth (sw) controls how many spaces a single indentation level uses for operations like >>, <<, and automatic indentation. I usually do :setlocal shiftwidth=4 for projects that use four-space indents. tabstop (ts) sets how many spaces a literal TAB character displays as; use :set tabstop=4 to make existing tabs line up visually with your intended width. softtabstop (sts) affects insert-mode behavior: :set softtabstop=4 makes pressing Backspace or Tab behave like you're working with 4-space logical tabs even if actual file uses tabs. A couple of other practical commands I keep in my .vimrc: :set expandtab to insert spaces instead of real tabs (or :set noexpandtab to keep tabs), :set autoindent to keep the previous line's indentation, and :set cindent or :set smartindent for C-like auto-indenting. If you want the changes to apply only to the current buffer, use :setlocal sw=2 ts=2 sts=2. To reformat an entire file after changing settings, I often run gg=G to reindent the whole buffer, or :retab to convert tabs to spaces (or the reverse with :retab!). These little tweaks saved me hours when I was switching between Python, Makefiles, and Go projects.

Okay, here's a practical and friendly way I handle Vim's auto-indent when I need it out of the way for a few moments. If I just want to paste something without Vim reformatting it, I usually toggle paste mode: :set paste to turn it on, paste the text, then :set nopaste to go back. I often map a key for that so it’s painless, for example :set pastetoggle= or put in my config nnoremap :set paste! to flip it. Paste mode stops auto-indent, indentexpr, and other niceties, so your pasted code won't get mangled. If I need to disable automatic indentation for editing (not just pasting), I prefer buffer-local switches so I don’t mess with other files: :setlocal noautoindent nosmartindent nocindent and, if needed, :setlocal indentexpr= to clear any expression-based indent. To restore, use :setlocal autoindent smartindent cindent or reopen the buffer. Little tip: :set paste? shows whether paste is on. Personally, I use paste for quick fixes and :setlocal for longer edits — keeps things predictable and quiet during a frantic refactor.

Man, that frustration is so real — I’ve been there. First thing I do is check whether vim even thinks it should indent: open the file and run :set filetype? and :verbose set autoindent. If filetype is empty or wrong, indent scripts won’t run. If :verbose shows autoindent being turned off by some script, that points to the culprit. Next, consider obvious toggles that silently kill indentation: if you’ve got 'set paste' enabled (or you toggled paste mode earlier with a mapping), indentation won’t behave. Also check whether you disabled 'autoindent', 'smartindent', or 'cindent' by mistake. Use :set paste? and :set autoindent? to inspect current state. If those look fine, source your vimrc manually (:source ~/.vimrc) and watch :messages for errors — a syntax error early in the file can stop the rest of the config from loading, so later indent settings never get applied. Also run vim -u NONE (or nvim -u NORC) to see if a vanilla session indents correctly; if it does, a plugin or a line in your vimrc is to blame. Useful commands: :scriptnames (shows loaded scripts), :verbose set shiftwidth? tabstop? expandtab? and checking ~/.vim/indent or plugin ftplugin files for overrides. If you want, paste the problematic snippet and I’ll poke at it with you.

Okay, this is the hot take I give my friends when they ask how to stop JavaScript files from turning into a jagged mess: treat indentation as a filetype thing, not a global, and use 2 spaces plus an actual JS-aware indent engine. I usually put this in my vimrc (or better, in ftplugin/javascript.vim): filetype plugin indent on autocmd FileType javascript,typescript setlocal shiftwidth=2 softtabstop=2 tabstop=2 expandtab autocmd FileType javascript,typescript setlocal autoindent smartindent Those lines give you consistent 2-space soft tabs (the de facto style for many JS projects) and rely on Vim's smartindent for basic braces. But honestly, for real-world code with ES6/JSX/template literals, install a javascript-indent plugin (like the popular one that provides an indentexpr) and let it set indentexpr for you; it handles arrow functions, template literals and some weird edge cases better than plain smartindent. I also map = to re-indent visually: vmap = = or use gg=G to reformat a whole file. Finally, I pair this with an on-save formatter — 'prettier' is my go-to — so even when teammates differ, my local formatting is predictable. If you want the exact plugin names or a sample ftplugin that runs Prettier on save, I can paste that too.

Honestly, getting Python auto-indent working in vim is one of those tiny victories that makes editing a joy. My go-to is to enable vim's filetype detection and then set sensible Python indentation rules in my config. Add these lines to your ~/.vimrc or init.vim for Neovim: filetype plugin indent on set autoindent set expandtab set shiftwidth=4 set softtabstop=4 set tabstop=4 The first line turns on filetype-specific plugins and indent scripts (this loads vim's python indent file). The rest make tabs into spaces and use four spaces per indent, which is the common Python convention. If you want the setting to apply only to Python buffers, drop the global lines into ~/.vim/ftplugin/python.vim and use setlocal instead of set. If indentation still feels off, check the buffer's filetype with :set filetype? and inspect loaded scripts with :scriptnames. I sometimes install a plugin like 'vim-python-pep8-indent' or use external formatters like 'black' called via a formatter plugin to normalize whitespace. Try opening a .py and typing an indented block — it should behave. If not, tell me what output :set filetype? and :verbose set shiftwidth? give and we can debug further.

Okay, I’ll gush a bit: if you want auto-indent to actually behave instead of randomly guessing, start by combining a detector, a language-aware indenter, and a formatter. I like using vim-sleuth to sniff tabs vs spaces and shiftwidth automatically; it fixes half my headaches before I even open the file. After sleuth, for Neovim I plug in nvim-treesitter with its indent module turned on — it understands syntax much better than old regex-based indent scripts. Pair that with either null-ls or coc.nvim (or ale if you prefer linters/formatters) to run real formatters like prettier, clang-format, shfmt, or rustfmt on save. That lets the language tools correct structural indentation rather than vim guessing. Small extras that helped me: editorconfig-vim to respect project settings, indent-o-matic as a fallback detector in weird repos, and indent-blankline.nvim for visual guides so you can spot mistakes. Also don't forget filetype plugin indent on and sensible defaults (autoindent, smartindent/cindent where appropriate). With those layered, indentation accuracy improves dramatically and my diffs stop being a jungle of whitespace edits.

If you've ever opened a file in Vim and wondered why indentation behaves one way in one project and differently in another, the way filetype plugins and indent scripts interact is the usual culprit. In my messy but beloved setup I keep separate snippets in ~/.vim/ftplugin/ and ~/.vim/indent/ and they each have a job: ftplugin files generally set buffer-local editing options (things like shiftwidth, tabstop, expandtab, mappings) while indent scripts (under indent/) provide indentation logic by setting 'indentexpr', 'cindent', 'indentkeys', or related buffer-local options. Because these are buffer-local, whichever script writes a particular option last wins for that buffer. Practically that means you can get conflicts. An ftplugin might set 'shiftwidth' to 4 for 'python' and an indent script might expect 2; or an indent script will set 'indentexpr' to a custom function that overrides simpler behaviors such as 'autoindent'. The usual fixes I use are: enable both with :filetype plugin indent on, then put overrides in after/ftplugin/ or after/indent/ so they load later; or explicitly set local options with setlocal in a ftplugin; or prevent an indent script with let b:did_indent = 1 if you deliberately want to skip it. For debugging, :scriptnames shows what got sourced, and :verbose setlocal shiftwidth? / :verbose setlocal indentexpr? tell you who last changed a setting. I like keeping ftplugin for styling and small mappings, and leaving indentation math to indent scripts — but I always keep an 'after' copy for those moments when I need the last word.

I'll be blunt: yes, you absolutely can set up Vim to auto-indent differently per project directory, and I've done it a bunch of times across projects with different coding styles. When I need a project-specific policy I usually pick one of three safe routes: use a repository-level '.editorconfig' with the EditorConfig Vim plugin (works across editors and is a huge life-saver), add per-project autocommands in my global vimrc that match the project path, or—if I must—use a controlled local vimrc mechanism (with security checks). For example, in your main vimrc you can add an autocmd that applies settings only when the buffer lives under a particular path: augroup proj_indent autocmd! autocmd BufRead,BufNewFile /path/to/myproj/* setlocal shiftwidth=4 tabstop=4 expandtab augroup END That keeps the rules scoped to files under that directory. I avoid blindly enabling 'exrc' because executing arbitrary project .vimrc files can be risky; instead I either require a checked-in '.editorconfig' or use a trusted plugin like 'localvimrc' that prompts you before sourcing. Also remember to use setlocal so other projects aren’t affected. For Neovim, the same autocmds work, but I often detect the project root via an LSP/root_pattern helper and then apply settings dynamically. Overall, choose EditorConfig if you want a cross-editor approach, or autocommands if you prefer staying purely in Vim land.