How do I customize Vim's statusline to show useful file information?

Explanation

Vim's statusline option lets you build a custom status bar from format items. A well-configured statusline surfaces the current filename, file type, cursor position, and more — all without a plugin.

How it works

%f\ %y\ [%l/%L] uses statusline format specifiers:

• %f — Relative path of the current file
• \ — A literal space (the backslash escapes it in the :set command)
• %y — File type in brackets, e.g. [go], [python]
• %l — Current line number
• %L — Total number of lines in the buffer

You can extend this with more items:

• %m — Modified flag ([+] when unsaved changes exist)
• %r — Readonly flag ([RO])
• %c — Current column number
• %p%% — Percentage through the file (the %% outputs a literal %)
• %= — Separator that pushes everything after it to the right side

Example

A practical statusline for your vimrc:

set laststatus=2
set statusline=%f\ %m%r%y\ %=%l/%L\ col:%c

With a modified Go file open at line 42 of 200, column 10, this displays:

src/main.go [+][go]              42/200 col:10

Tips

• set laststatus=2 ensures the statusline is always visible (not just in split windows).
• Wrap sections in %{...} to embed Vimscript expressions: %{&fileencoding} shows encoding.
• Use %#GroupName# to apply highlight groups for color: %#WarningMsg#%m%#StatusLine#.
• For complex statuslines, assign a string to &statusline in your vimrc rather than using :set.