How do I open a related file with a different extension using the current filename?

Explanation

In Vim's command line, % expands to the current buffer's filename. You can append filename modifiers to transform it — making it easy to open related files, split into a sibling directory, or construct paths without typing filenames manually.

How it works

Modifiers are appended after % with a colon:

• %:r — root: strip the last extension (src/foo.c → src/foo)
• %:e — extension only (src/foo.c → c)
• %:t — tail (basename, no directory) (src/foo.c → foo.c)
• %:h — head (directory only) (src/foo.c → src)
• %:p — full absolute path
• %:p:h — directory of the current file (modifiers chain)

Example

Editing src/components/Button.tsx and you want to open its CSS module:

:e %:r.css

This expands to :e src/components/Button.css. Or to browse the same directory:

:e %:p:h/

This opens netrw in the current file's directory. Or to open the test file:

:e %:r.test.ts

Tips

• Use <Tab> to complete after the modifier (e.g., :e %:p:h/<Tab>)
• These modifiers also work in :read, :write, :split, :vsplit
• %:t:r chains modifiers: basename without extension (src/foo.c → foo)
• The # register holds the alternate filename and supports the same modifiers: #:r, #:h etc.
• Preview the expansion without opening: :echo expand('%:p:h')