1.最左侧显示行号
在emacs的配置文件（~./.emacs.d/init.el）文件里添加如下内容：
(add-to-list 'load-path "/usr/share/emacs/site-lisp")
(require 'linum)(global-linum-mode t)2. emacs无法输入中文（针对gentoo，其他linux系统可参考）
首先应该先检查字体配置, 然后检查是否开启eamcs的xft的USE标示符.
安装 font-cursor-misc 或 font-adobe-75dpi ，重启计算机测试(好像大部分是因为缺少这个语言包的问题)
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安装：
1). [ebuild N ] media-fonts/font-adobe-75dpi-1.0.0 USE="X nls" 0 kB2). [ebuild N ] x11-apps/bdftopcf-1.0.2 USE="-debug" 0 kB3). [ebuild N ] media-fonts/font-alias-1.0.1 USE="-debug" 0 kB4). [ebuild N ] media-fonts/font-util-1.1.1 USE="-debug" 0 kB
3. 在emacs文件的标题栏显示该文件的绝对路径: （好处是当你打开多个同名文件时，易于区分）
(setq frame-title-format ("%S" (buffer-file-name "%f" (dired-directory dired-directory "%b"))))
4. 如果不想显示绝对路径，只是想显示该文件的名称
(setq frame-title-format "XX@%b")，其中XX为自己的电脑名，或自己可任意取名，甚至可以不需要。
5. linux下为emacs定制c/c++ 和python代码的自动提示
从 Emacs 24 开始，Emacs 对扩展包进行统一管理，极大程度上简化了扩展包的搜索与安装过程。打开 Emacs，然后执行 M-x list-packages ，如果网速足够快，应该很快就能看到 Emacs 官方提供的扩展包列表。
待软件包列表出现后，执行 C-s M-r ^ +company ，回车即可让光标跳到 company 扩展包信息所在的文本行，继而敲击 i 键（表示要安装该扩展包），再敲击 x 键（表示执行安装过程），稍等片刻，Emacs 会自动从下载 company 扩展包并安装至 $HOME/.emacs.d 目录。
提示：C-s 是开启 Emacs 查找模式， M-r 是将查找模式切换为正则表达式查找模式，而 C-s(ctrl +s) M-r(Alt + r) ^ + company 是用于匹配『位于行首且由多个空格与 company 字符串构成的字符串』的正则表达式。
如果以后要删除 company 扩展，步骤与安装步骤类似，只是将 i 键替换为 d 键（表示删除）。company 安装完毕后，在 Emacs 配置文件中做以下配置：
;; 代码补全
(add-hook 'c-mode-hook 'company-mode)(add-hook 'c++-mode-hook 'company-mode)。对于pcl的代码提示功能，只需要安装 company的关于C/C++的头文件即可.(目前是这样的)
在linux下，若emacs启动较慢，可通过hostname查看自己主机的名字，然后打开/etc/hosts文件，将其中localhost改为自己主机名
6.最后贴一下自己的emacs配置文件
;; 关闭启动时的 “开机画面”，将缺省主模式设为 text-mode(setq inhibit-startup-message t);; 语法高亮(global-font-lock-mode t);; 以y/n代表yes/no(fset 'yes-or-no-p 'y-or-n-p);; 显示括号匹配(show-paren-mode t)(setq show-paren-style 'parentheses)(transient-mark-mode t);; 在标题栏提示你目前在什么位置(setq frame-title-format "yxg@%b");;(setq frame-title-format '("%S" (buffer-file-name "%f" (dired-directory dired-directory "%b"))));; 默认显示100列就换行(setq default-fill-column 100);; 去掉工具栏;;(tool-bar-mode 0);; 去掉菜单栏;;(menu-bar-mode 0)(scroll-bar-mode 0)(tooltip-mode 0);; 显示列号、行号(setq column-number-mode t)(setq line-number-mode t);; 回车缩进(global-set-key "\C-m" 'newline-and-indent)(global-set-key (kbd "C- ") 'newline);;(global-unset-key (kbd "C-SPC")) ;;(global-set-key (kbd "M-SPC") 'set-mark-command);;;; c mode ;;;;(defvar xgp-cfsi-left-PAREN-old nil "Command used to input \"(\"")(make-variable-buffer-local 'xgp-cfsi-left-PAREN-old)(defun xgp-cfsi-modify-alist (alist term new) (let ((tl (assq term (symbol-value alist)))) (if tl (setcdr tl new) (add-to-list alist (cons term new)))))(defun xgp-cfsi (style) "Deciding whether using CFSI." (interactive "Style: ") (c-set-style style) (setq indent-tabs-mode nil c-hanging-semi&comma-criteria (quote (c-semi&comma-inside-parenlist))) (xgp-cfsi-modify-alist 'c-hanging-braces-alist 'class-open nil) (xgp-cfsi-modify-alist 'c-hanging-braces-alist 'class-close nil) (local-set-key " " 'self-insert-command))(defun xgp-cfsi-erase-blanks () "Erase all trivial blanks for CFSI." (interactive) (save-excursion (goto-char (point-min)) (while (re-search-forward "[ \t]+$" nil t) (replace-match "" nil nil))))(defun linux-c-mode() (define-key c-mode-map [return] 'newline-and-indent) (setq imenu-sort-function 'imenu--sort-by-name) (interactive) (imenu-add-menubar-index) (which-function-mode) (c-toggle-auto-state) (c-toggle-hungry-state) (setq indent-tabs-mode nil) (xgp-cfsi "linux"))(add-hook 'c-mode-common-hook 'linux-c-mode);; MELPA 扩展包仓库(when (>= emacs-major-version 24) (require 'package) (add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t) (package-initialize));; 代码补全(add-hook 'c-mode-hook 'company-mode)(add-hook 'c++-mode-hook 'company-mode);;(eval-after-load 'company;; '(add-to-list 'company-backends 'company-irony));; 左侧行号显示(add-to-list 'load-path "/usr/share/emacs/site-lisp")(require 'linum)(global-linum-mode t)(custom-set-variables ;; custom-set-variables was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(column-number-mode t) '(show-paren-mode t))(custom-set-faces ;; custom-set-faces was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(default ((t (:family "Liberation Mono" :foundry "1ASC" :slant normal :weight normal :height 98 :width normal)))));;;;;;;;;;;;;;;;;;;;; for zero ;;;;;;;;;;;;;;;;;;;;;;;;;;(add-hook 'c-mode-hook (lambda () (font-lock-add-keywords nil '(("\\(@ *[^@#]+ *#\\) *[;]*[ ]+" 1 font-lock-function-name-face t) ("^ *\\(@\\) *$" 1 font-lock-function-name-face t)))))(defun zero-quantum () (interactive) (insert "@ ") (insert " #\n\n@") (backward-char 5))(define-prefix-command 'ctl-z-map)(global-set-key (kbd "C-z") 'ctl-z-map)(global-set-key (kbd "C-z c") 'c-mode)(global-set-key (kbd "C-z t") 'tex-mode)(global-set-key (kbd "C-z m") 'markdown-mode)(global-set-key (kbd "C-z q") 'zero-quantum)