Vim: Performing Case-Insensitive Searches

Vim performs case-sensitive searches by default. If you search for error, it won’t match Error or ERROR. Here are several ways to enable case-insensitive searching.

Toggle Case Sensitivity During Search

The quickest method — append \c anywhere in your search pattern:

/error\c

This matches error, Error, ERROR, and any other casing. The \c flag applies only to the current search.

Conversely, use \C to force case-sensitive search when ignorecase is enabled:

/error\C

Set ignorecase Globally

Make all searches case-insensitive by default:

:set ignorecase

Or the shorthand:

:set ic

Add it to your ~/.vimrc for permanent effect:

set ignorecase

Smart Case Sensitivity

The best option for most users — combine ignorecase with smartcase:

set ignorecase
set smartcase

With smartcase:

Searching for error (all lowercase) — case-insensitive, matches Error, ERROR
Searching for Error (contains uppercase) — case-sensitive, matches only Error

This gives you the best of both worlds: casual lowercase searches are flexible, while uppercase searches are precise.

Toggle During a Session

Quick key mappings in your ~/.vimrc:

" Toggle ignorecase with leader+i
nnoremap <leader>i :set ignorecase!<CR>

" Show current setting
nnoremap <leader>I :set ignorecase?<CR>

Or use the built-in toggle shortcut — press / to start search, then Ctrl+C to toggle case sensitivity (with some Vim configurations).

Case-Insensitive Substitution

The \c flag also works with substitute commands:

:%s/error/issue/gc\c

Wait — the flag goes in the pattern, not after the flags:

:%s/error\c/issue/gc

This replaces all casings of “error” with “issue”, asking for confirmation on each match.

Search With Very Magic Mode

For complex patterns with case-insensitivity:

/\v\cerror_\d+

The \v (very magic) makes special characters work without escaping, and \c enables case-insensitivity. The order doesn’t matter — \c\v works too.

Search History and Case

Vim remembers search patterns with their case settings. Browse search history with / then arrow keys. Each pattern retains its \c or \C flag from the original search.

Clear search highlighting after a search:

:nohlsearch

Or map it to a convenient key:

nnoremap <Esc> :nohlsearch<CR>

Quick Reference

/pattern\c — Case-insensitive for this search only
/pattern\C — Case-sensitive for this search only
:set ic — Global case-insensitive
:set smartcase — Smart case (use with ic)
:%s/old\c/new/g — Case-insensitive substitution

Case-Insensitive Search in Visual Mode

When searching for the visually selected text, add case-insensitivity:

" Search visual selection (case-insensitive)
vnoremap // y/\V<C-R>"\c<CR>

This yanks the selected text, then searches for it literally (\V very nomagic) with case-insensitivity (\c).

Using * and # with Case-Insensitivity

The * and # keys search for the word under the cursor. With ignorecase set, they automatically become case-insensitive. Without it, make them case-insensitive with a mapping:

" Case-insensitive word search
nnoremap * /\<\=expand('<cword>')\>\c<CR>
nnoremap # ?\<\=expand('<cword>')\>\c<CR>

Plugin: vim-slash

The vim-slash plugin improves search highlighting and automatically clears it after moving:

" Install with vim-plug
Plug 'junegunn/vim-slash'

It doesn’t affect case sensitivity directly, but it enhances the search experience by making highlights less intrusive.

Neovim Differences

In Neovim, the same settings work identically:

set ignorecase
set smartcase

Neovim also supports the /\c and /\C inline flags the same way as Vim. The configuration goes in ~/.config/nvim/init.lua (Lua) or init.vim (Vimscript).