emacs opens shells in a random window, how to change this?

Question

Try splitting the frame repeating some times the command C-x 3. Then try open the shell with M-x shell.

It will open in a random window and not the one which you have typed the command from. Why?

Answer 1

The reason is that shell uses pop-to-buffer.

If you want to use the selected window try this in your config.

(add-to-list 'display-buffer-alist
             `(,(rx bos "*shell*")
               display-buffer-same-window
               (reusable-frames . visible)))

Answer 2

The following works well in my GNU Emacs 25.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.24.23) of 2017-12-09

(add-to-list 'display-buffer-alist
             `(,(rx bos "*shell*")
              display-buffer-same-window))

However, with the answer provided by @bertfred I get the error

(wrong-type-argument window-live-p nil)

EDIT:

Here is the content of the *Backtrace* buffer after M-x shell with @bertfred's suggested display-buffer-alist:

Debugger entered--Lisp error: (wrong-type-argument window-live-p nil)
  select-window(nil nil)
  pop-to-buffer(#<buffer *shell*>)
  shell(nil)
  funcall-interactively(shell nil)
  call-interactively(shell record nil)
  command-execute(shell record)
  execute-extended-command(nil "shell" "shell")
  funcall-interactively(execute-extended-command nil "shell" "shell")
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)