How do I open a file in a read-only split window in Vim?

Explanation

The :sview command opens a file in a horizontal split window with the buffer set to read-only. It combines :split and :view into a single command, giving you a side-by-side reference view of another file without any risk of accidentally editing it. This is especially useful when you need to consult a config file, reference implementation, or documentation file while working in the main window.

How it works

• :view {file} — opens a file in the current window as read-only ('readonly' is set)
• :sview {file} — same, but first creates a new horizontal split
• In a read-only buffer, attempting to write warns: E45: 'readonly' option is set
• You can still copy text, navigate, and search freely
• To open in a vertical split instead: :vert sview {file}

Example

:sview ~/.ssh/config

This splits the window and shows ~/.ssh/config read-only above (or below) your current file:

+---------------------------+
| ~/.ssh/config  [RO]       |
|   Host dev-server         |
|     HostName 10.0.0.1     |
+---------------------------+
| current file.go           |
|   ...                     |
+---------------------------+

Tips

• Use tab completion: :sview <Tab> works just like :e <Tab>
• To also open in a vertical split: :vertical sview {file} or :vert sview {file}
• Close the split with :q or <C-w>q
• To force-write a read-only buffer if needed: :w! (or :set noreadonly first)
• The related command :pedit opens a file in the preview window (:pclose to close)