这是一个简单的场景，目的是将其他语言编写的程序集成到emacs里面，而不是打开emacs shell，执行这个脚本。
假设有一个文件，里面存放的是文本，用emacs打开，
然后选择一段文本
现在运行一个自定义命令M-x get-length
get-length会运行预先准备好的newlisp脚本，来统计被选中的文本的长度，输出到一个新的 buffer，并显示该buffer.
现在准备一个文本文件: input.txt，里面有一堆字符串
maaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddmaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddmaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddmaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddmaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddmaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd
编写一个elisp文件region.el
(defun region-length (startPos endPos)
"Do some text processing on region. This command calls the external script “wc”."
(interactive "r")
(let (cmdStr)
(setq cmdStr "/your/path/length.lsp") ; full path to your script
(shell-command-on-region startPos endPos cmdStr nil nil nil t)
(switch-to-buffer-other-window "*Shell Command Output*")
)
)
说明：
shell-command-on-region的第4个参数nil表示会打开*Shell Command Output* buffer.
newlisp脚本lenght.lsp输出的结果到stdout，会写入到这个buffer中. newlisp脚本需要设置绝对路径
现在看一下length.lsp
#!/usr/bin/newlisp (while (read-line) (setf str (current-line)) (println (length str)) ) (exit)
现在测试一下:
M-x load-file 加载region.el
然后打开input.txt buffer,选中几个字符
M-x region-length
结果会打开一个buffer，显示长度。
