Changing character case in VIM

There are caces when you need to change the case of a word in VIM. In this post, you will learn how to do that in various ways, each with its own use case.

Commands

In VIM, there are commands to change character case:

• gu - Change to lowercase.
• gU - Change to uppercase.
• g~ - Toggle case.

All the commands can be used in combination with text objects to change the case of a word or a sentence. For example, guaw will change the case of the word under the cursor to lowercase, g~ap will toggle the case of the paragraph under the cursor. The commands can also be used with selections, for example, gu will change the case of the selected text to lowercase, gU will change the case of the selected text to uppercase, and g~ will toggle the case of the selected text.

Examples

Consider you have the following text in your VIM editor:

this is an important text that needs to be capitalized.
                                                      ^ cursor position

And you want to change the case of the word important to uppercase. Here are some ways to do that:

1. Type 3Fi to move the cursor back to the beginning of the word important.
2. Type gUiw to change the word to uppercase.
3. Press ESC to exit insert mode.

After performing the above steps, the text will look like this:

this is an IMPORTANT text that needs to be capitalized.

substitution

Changing character case with commands can be handy, but sometimes you might want to change the character case by searching patterns and replacing them with the desired case. Changing character case can be also done in the :s command.

The following are some replacement examples of changing character case in substitution:

• \U - uppercase everything after this until the end of the pattern.
• \L - lowercase everything after this until the end of the pattern.
• \u - uppercase the next character.
• \l - lowercase the next character.
• \e or \E - end the case change.

Examples

Consider you have the following text in your VIM editor:

this is an important text that needs to be capitalized.
^ cursor position

And you want to capitalized each word in the text. Here are some ways to do that:

1. Type :s/\w\+/\u&/g to capitalize each word in the text.
2. Press Enter to execute the command.
3. Press ESC to exit insert mode.

After performing the above steps, the text will look like this:

This Is An Important Text That Needs To Be Capitalized.

In the command, \w\+ matches one or more word characters, & is the matched pattern, and \u& capitalizes the matched pattern, g is used to replace all occurrences in the line.