How do I reuse the replacement text from my last substitution in a new one without retyping it?

Explanation

In a Vim substitution, using ~ as the replacement string repeats the replacement text from the most recent :s command. This is handy when you want to apply the same transformation to a different pattern, or when you need to re-run a substitution with a different search term but the same result text.

How it works

• ~ in the replacement field of :s expands to the last used replacement string
• It is distinct from \~ (which also works in some contexts) and from :~ (a separate command that re-applies the last substitution with the last search pattern)
• The remembered replacement persists until you run another :s command with a different replacement

Example

First, apply a substitution that replaces foo with [REDACTED]:

:%s/foo/[REDACTED]/g

Now, without retyping [REDACTED], apply the same replacement to a different pattern:

:s/secret_value/~/

This replaces secret_value with [REDACTED] — the ~ expanded to the previous replacement.

Before: api_key = secret_value
After:  api_key = [REDACTED]

Tips

• Combine with :~ to apply the last substitute's search pattern as well: after :s/foo/bar/, running :%~ repeats :s/foo/bar/ across the whole file
• Use ~ when scripting repetitive transformations where the target varies but the replacement is always the same
• See :help s/~ and :help :~ to understand the subtle distinction between the two