.emacs in order to backup/restore init files

dot.el

;;; -*- coding:utf-8; mode:emacs-lisp -*-
;;;
;;; ~/.emacs.d/dot.emacs
;;;
;;; $ ln -s ~/.emacs.d/dot.emacs ~/.emacs
;;;

;;
;; functionalities to backup/restore init files
;;
(defun backup-init-files-backup ()
  (let ((s "")
        (bak ""))
    (dolist (f backup-init-files-file-list)
      (unless (file-exists-p f)
        (setq s (concat s " " f))))
    (if (null (string= s ""))
        (message "not exists:%s" s)

      (dolist (f backup-init-files-file-list)
        (setq bak (concat f backup-init-files-ext-bak))
        (copy-file f bak t)
        (setq s (concat s " " f)))
      (message "backed up:%s" s))))

(defun backup-init-files-restore ()
  (interactive)
  (let ((s "")
        (bak "")
        (old ""))
    (dolist (f backup-init-files-file-list)
      (setq bak (concat f backup-init-files-ext-bak))
      (unless (file-exists-p bak)
        (setq s (concat s " " bak))))
    (if (null (string= s ""))
        (message "not exists: %s" s)

      (dolist (f backup-init-files-file-list)
        (setq bak (concat f backup-init-files-ext-bak))
        (setq old (concat f backup-init-files-ext-old))
        (copy-file f old t t)
        (copy-file bak f t)
        (setq s (concat s " " f)))
      (message "restored:%s" s))))

(defvar backup-init-files-ext-bak ".last-load")
(defvar backup-init-files-ext-old ".err")
(defvar backup-init-files-file-list '("~/.emacs.d/init.el"))

;;
;; package setting
;;
(require 'package)
(add-to-list 'package-archives '("gnu" . "http://elpa.gnu.org/packages/"))
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
(add-to-list 'package-archives '("melpa-stable" . "https://stable.melpa.org/packages/"))
(setq package-user-dir "~/.emacs.d/packages")
(package-initialize)
(unless (require 'use-package nil t)
  (defmacro use-package (&rest args)))

;;
;; load ~/.emacs.d/init.d
;;
(load "~/.emacs.d/init.el")

(backup-init-files-backup)                ; backup init files when loaded normaly

;; Use `M-x backup-init-files-restore' to restore init files if error occurs while startup Emacs.

;;
;; customize setting
;;
(setq custom-file "~/.emacs.d/custom.el") ; write custom settings into external file instead of init.el
(load custom-file t)

;;
;; dot.emacs ends here
;;