Passing Emacs variables to minibuffer shell commands

Question

I can run a shell command quickly by hitting M-!. One thing I'd like to do is perform shell quick operations on the current file. An example would be checking the file out through perforce: M-! `p4 edit buffer-file-name` RET (Yes there are perforce integrations, but I'm more interested in the minishell/variable problem rather than a specific workflow) Of course, the `buffer-file-name` variable is not evaluated before the command is sent to the shell. Is there an easy on-the-fly way to do this? Or will I have to roll a custom elisp function?

Accepted Answer

Indeed using C-u M-: is almost right. I'm not so sure about using `shell-quote-argument` in `eval-to-shell-argument` since it only works on strings making it impossible to use `eval-to-shell-argument` to insert a number or a symbol. You could try something like:

```
(defun sm-minibuffer-insert-val (exp)
  (interactive
   (list (let ((enable-recursive-minibuffers t))
           (read-from-minibuffer "Insert: "
                                 nil read-expression-map t
                                 'read-expression-history))))
    (let ((val (with-selected-window (minibuffer-selected-window)
                 (eval exp)))
          (standard-output (current-buffer)))
      (prin1 val)))
```

and then bind this function in your minibuffer with `(define-key minibuffer-local-map [?\M-:] 'sm-minibuffer-insert-val)`. Of course, if the only thing you ever want to insert is the buffer-file-name, then your `execute-shell-command-on-buffer` is simpler.

Passing Emacs variables to minibuffer shell commands

Solution

Problem