Return to Answer

kill-process is working in your case. But the loop is to fast. The first get-buffer-process next to while returns, right after killing cat, the handle to the cat buffer, but the next get-buffer-process near kill-process is returning nil. So kill-process tries to kill a different buffer (e.g.: "scratch").

A solution would be:

(let ((buf
       "*Async Shell Command*"))
  (async-shell-command "cat")
  (while (get-buffer-process buf)
    (message "still has proc")
    (kill-process (get-buffer-process buf))
    (sit-for 1)))

Another solution could be this:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (sit-for 1)
       (message "still has proc")))

kill-process is working in your case. But for a reason get-buffer-process does not return nil to while. Maybe because it refers to a buffer which is not yet closed, and emacs needs to take a breath? A sit-for command will fix this.

A solution would be:

(let ((buf
       "*Async Shell Command*"))
  (async-shell-command "cat")
  (while (get-buffer-process buf)
    (message "still has proc")
    (kill-process (get-buffer-process buf))
    (sit-for 0.01)))

Another solution could be not to use get-buffer-process:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (message "still has proc")))

kill-process is working in your case. But get-buffer-process is, after killing cat, returning the name of a different buffer (eg scratch). You can check this if you insert (sit-for 1) into your while-loop. Then you will get the debugger.

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (get-buffer-process buf)
       (sit-for 1)
       (message "still has proc")
       (kill-process (get-buffer-process buf))))

To solve this, you should rewrite your code to something like this:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (sit-for 1)
       (message "still has proc")))

Edit: the explanation is wrong, but the solution works. ;) i try to figure it out.

kill-process is working in your case. But the loop is to fast. The first get-buffer-process next to while returns, right after killing cat, the handle to the cat buffer, but the next get-buffer-process near kill-process is returning nil. So kill-process tries to kill a different buffer (e.g.: "scratch").

A solution would be:

(let ((buf
       "*Async Shell Command*"))
  (async-shell-command "cat")
  (while (get-buffer-process buf)
    (message "still has proc")
    (kill-process (get-buffer-process buf))
    (sit-for 1)))

Another solution could be this:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (sit-for 1)
       (message "still has proc")))

kill-process is working in your case. But get-buffer-process is, after killing cat, returning the name of a different buffer (eg scratch). You can check this if you insert (sit-for 1) into your while-loop. Then you will get the debugger.

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (get-buffer-process buf)
       (sit-for 1)
       (message "still has proc")
       (kill-process (get-buffer-process buf))))

To solve this, you should rewrite your code to something like this:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (sit-for 1)
       (message "still has proc")))

kill-process is working in your case. But get-buffer-process is, after killing cat, returning the name of a different buffer (eg scratch). You can check this if you insert (sit-for 1) into your while-loop. Then you will get the debugger.

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (get-buffer-process buf)
       (sit-for 1)
       (message "still has proc")
       (kill-process (get-buffer-process buf))))

To solve this, you should rewrite your code to something like this:

(let ((buf
          "*Async Shell Command*"))
     (async-shell-command "cat")
     (while (not (string= (kill-process buf) buf))
       (sit-for 1)
       (message "still has proc")))

Edit: the explanation is wrong, but the solution works. ;) i try to figure it out.