写了一段非常Naive的Common Lisp代码来读取/etc/os-release文件：
#|
OS-RELEASE
author: Song Wei ([email protected])
Read the /etc/os-release file naively.
Check page: https://www.freedesktop.org/software/systemd/man/os-release.html
License: this program is released in public domain, use at your own risks.
|#
(defpackage :os-release
(:use :cl :cl-user)
(:export read-os-release))
(in-package :os-release)
(defmacro while (test &rest body)
`(do ()
((not ,test))
,@body))
(defun make-dynamic-string ()
(make-array 0 :adjustable t
:fill-pointer 0
:element-type 'character))
;; (let ((s (make-dynamic-string)))
;; (vector-push-extend #\a s)
;; (vector-push-extend #\b s)
;; s)
(defun readline (file-stream)
(multiple-value-bind (line file-end-p)
(read-line file-stream nil nil)
(if (= 0 (length line))
(values nil file-end-p)
(let ((field (make-dynamic-string))
(value (make-dynamic-string))
(reading-value-flag nil)
(with-quote-p nil))
(block :reading-loop
(dotimes (i (length line))
(let ((c (aref line i)))
(cond ((char= c #\=)
(setf reading-value-flag t))
((and reading-value-flag (not with-quote-p) (char= c #\"))
(setf with-quote-p t))
((and reading-value-flag with-quote-p (char= c #\"))
(return-from :reading-loop))
(t
(vector-push-extend
c (if (not reading-value-flag) field value)))))))
(values (list (intern field "KEYWORD") value) file-end-p)))))
(defun read-os-release ()
(with-open-file (file-stream #p"/etc/os-release" :direction :input)
(let ((content nil)
(not-end t))
(while not-end
(multiple-value-bind (field ended) (readline file-stream)
(if ended
(setf not-end nil))
(if field
(setf content (concatenate 'list content field)))))
content)))
;; (getf (read-os-release) :name) => "Arch Linux"