有别于死板的 Shell + Terminal，http://xiki.org/ 给出了一种更为自由的执行命令的方法，受 xiki 启发（其实是它的演示视频，因为我安装不上它）想到一个执行 Shell 命令的方法（下图、代码）：
(defun $ (pattern)
"Run shell command in the current line and insert the output."
(interactive
(list (buffer-substring-no-properties
(line-beginning-position)
(line-end-position))))
(let (directory command)
(pcase pattern
((rx bos "$ " (let cmd (1+ anything)) eos)
(setq directory default-directory
command cmd))
((rx bos (let dir (1+ (not (in " ")))) " $ " (let cmd (1+ anything)) eos)
(setq directory dir
command cmd))
(_ (user-error "Unrecognized format, support '$ date' and '~/.emacs.d $ pwd'")))
(save-excursion
;; Delete old output
(delete-region (progn (forward-line)
(point))
(progn (while (get-text-property (point) '$)
(forward-line))
(point)))
(unless (bolp) (insert "\n"))
(insert
(with-temp-buffer
(let ((default-directory directory))
(shell-command command t)
(propertize (buffer-string) '$ t 'rear-nonsticky t)))))))