Vim Search Ignore Case

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Searching, or pattern matching, is a foundational Vim skill: Simply enter / and a string to find the next match. You can navigate files quickly this way by hitting <enter> after searching to jump to the first match. By default, these patterns are case sensitive. Searching for FooBar will not match references to foobar. But Vim search ignore case can be enabled using a combination two options I’d recommend:

  • set ignorecase – Makes pattern matching case-insensitive
  • set smartcase – Overrides ignorecase if your pattern contains mixed case

With this powerful combination of options, you get the best of both worlds: Using lowercase in your pattern will automatically match any case. But using one or more uppercase characters in your pattern will restrict matches to exact, case-sensitive matches. Set these options in your .vimrc to ignore case in Vim search.

Bonus trick: If you include \c anywhere in your pattern, the entire pattern functions as if ignorecase is on (the values you have set for these two options are ignored). If you use \C somewhere in your pattern, then Vim will force matching case for the pattern.

Here’s a short video where I demonstrate these two options in practice. I first enable them from Vim command mode. Then I search for colin in lower case. You can see it matches every reference, including the mixed-cased Colin. That is thanks to ignorecase. Next, I search for Colin. Because I’ve enabled smartcase, Vim knows I want a case-sensitive search and finds only the exact match. Try it out!

Demo of Ignoring Case in Vim Search

Also check out these two previous search-related posts:

How do I ignore case in Vim search?

To ignore case in Vim search by default, set the ignorecase option in your .vimrc by adding the following line:

set ignorecase

Get an even better experience by enabling the smartcase option in your .vimrc with the following line:

set smartcase

This will match exact-case text when you use a mixed-case pattern.

Why would I want to ignore case?

Using the search function with / is a fast way to navigate through documents in Vim. By ignoring Vim search case by default, you can match patterns faster by typing less. You can get the best of both worlds by enabling smartcase in Vim. There's a reason it's called smart case -- it enables moving very quickly through files but allow allows exact case match searching when needed.

How does the \c and \C overrides work?

Although it seems a but unintuitive, including either \c or \C inside your search pattern will override these options. Note that they are not flags for the end, but rather escaped characters you include inside your pattern. Check out these ignore case search override examples from the Vim docs:

\cfoo will match foo, Foo, or FOO no matter what your settings are. And foo\C will match only foo.

What are the Vim ignorecase docs?

If the ignorecase option is on, the case of normal letters is ignored. smartcase can be set to ignore case when the pattern contains lowercase letters only. When \c appears anywhere in the pattern, the whole pattern is handled like ignorecase is on. The actual value of ignorecase and smartcase is ignored. \C does the opposite: Force matching case for the whole pattern. {only Vim supports \c and \C} Note that ignorecase, \c and \C are not used for the character classes.

Examples:
      pattern   'ignorecase'  'smartcase'       matches
        foo       off           -               foo
        foo       on            -               foo Foo FOO
        Foo       on            off             foo Foo FOO
        Foo       on            on                  Foo
        \cfoo     -             -               foo Foo FOO
        foo\C     -             -               foo

What are the Vim smartcase docs?

smartcase scs boolean (default off) global

Override the ignorecase option if the search pattern contains upper case characters. Only used when the search pattern is typed and ignorecase option is on. Used for the commands /, ?, n, N, :g and :s.

Not used for *, #, gd, tag search, etc. After * and # you can make smartcase used by doing a / command, recalling the search pattern from history and hitting .

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Written by

Colin Bartlett

102 Posts

Vim enthusiast and software developer for more than 20 years.
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