How do I control windows using Ex commands in scripts and mappings instead of Ctrl-W shortcuts?

Explanation

:wincmd {key} is the Ex command equivalent of every <C-w>{key} window shortcut. It lets you perform any window operation — split, move focus, resize, rotate — from a place where keybindings cannot be sent directly: Vimscript functions, autocmds, and command-line mappings.

How it works

:wincmd takes exactly one argument: the key you would press after <C-w>. Any <C-w>{key} combination maps 1:1 to :wincmd {key}:

:wincmd h   " move focus to the left window   (<C-w>h)
:wincmd v   " open a vertical split           (<C-w>v)
:wincmd =   " equalize all window sizes       (<C-w>=)
:wincmd K   " move window to top              (<C-w>K)
:wincmd z   " close the preview window        (<C-w>z)

Example

In a Vimscript function, you can't easily send <C-w> keycodes. Use :wincmd instead:

function! FocusQuickfix()
  copen
  wincmd J   " push the quickfix window to the bottom
  wincmd p   " jump back to the previous window
endfunction

In an autocmd — equalize splits whenever a window is resized:

autocmd VimResized * wincmd =

In a mapping — avoids the <C-w> prefix in the RHS:

nnoremap <silent> <leader>= :wincmd =<CR>

Tips

• :h wincmd lists all accepted keys
• execute 'wincmd ' . key_variable lets you build the command dynamically
• {count}wincmd {key} passes a count, e.g. :5wincmd > widens the window by 5 columns