How do I match only part of a search pattern in Vim using \zs and \ze?

Explanation

Vim's \zs (start of match) and \ze (end of match) atoms let you control which portion of a pattern is treated as the actual match. The full pattern is still used to locate text, but only the part between \zs and \ze is highlighted or affected by substitutions. This is invaluable for complex search-and-replace operations where you need context anchoring without replacing the context itself.

How it works

• \zs — Sets the start of the match. Everything before it is required for the pattern to match, but is not included in the match result.
• \ze — Sets the end of the match. Everything after it is required for the pattern to match, but is not included in the match result.
• \v — Enables "very magic" mode so you don't need to escape most special characters.

You can use either atom alone or both together.

Example

Suppose you want to replace bar only when it follows foo:

:%s/\vfoo\zsbar/baz/g

Before:

foobar foobaz somebar

After:

foobaz foobaz somebar

Only the bar in foobar is replaced — somebar is untouched because it lacks the foo prefix.

Tips

• Use \ze to anchor the end: /\vfoo\zebar highlights only foo when followed by bar.
• These atoms are similar to lookahead/lookbehind in other regex flavors but are more intuitive for substitution.
• Combine with \zs in substitutions to avoid capture groups entirely — cleaner than \(\) with back-references.