Vim’s search and replace feature is powerful. It allows you to search for patterns with regular expressions.

Use the manual’s entry via :h pattern-searches for the help menu.

The basic usage for search in normal mode is / followed by the pattern for a forward search, and ? followed by a pattern for a backwards search.

Search and replace: :s/<pattern to replace>/<replacement>/<flags>

Search and replace in file: :%s/<pattern to replace>/<replacement>/<flags>

Below are useful tricks I found that may not be obvious to a casual Vim user.

Replace Command Separators

You can change the separators between different commands. That’s useful if you want to replace something with forward slashes.

Example:
You want to replace github.com/my-username in the complete file.

:%s/github.com\/my-username/gitlab.com\/my-other-username/g

Notice how you need to escape the slashes with a backslash.

Instead you can do this:

:%s_github.com/my-username_gitlab.com/my-other-username_g

I didn’t find this gem in the documentation, but came upon this idea by borrowing how the sed utility does it. Turns out, Vim can do that, too.

Further Reading:

Changing Case

Let’s say you want to replace something with an uppercase word but can’t be bothered to type your replacement string in uppercase.

Let’s replace all github with GITLAB:

:%s/github/\Ugitlab/g

\U transforms all following characters into uppercase.

See :h sub-replace-special.

Source: Changing case with regular expressions

Fine-Grained Control with the global Flag

You can separate the match from the substitution:

:% g/foo/s/bar/zzz/g

Translation: for every line containing “foo” substitute all “bar” with “zzz.”

Source: Your problem with Vim is that you don’t grok vi.

Use the Argument List to Search and Replace in Multiple Files

Use the :args command to collect a list of files which match a pattern.

For example, find all files that contain the string github:

args `grep -l github`

Then open the argument list with :args again.

Run search and replace with :argdo:

:argo %s/github/GitHub/g

Source: Vim search replace all files in current (project) folder