Comment/uncomment line(s) is easy in Emacs

It's easy if you use evil-nerd-commenter. As its README said, comment/uncomment line is only pressing ",ci" in evil-mode.

You can also select the region and press "M-;" to comment the lines in the region. If part of the line is not in the region, the whole line will still be commented out. This saves your extra key pressing for moving cursor to the beginning of the first line or moving the cursor to the end of the last line.

The reason to make commenting so efficient is that I need comment/uncomment code for debug purpose.

Some people say comment out the code is not a right way to debug. The right way is using debugger.

But if you debug some huge project, using the debugger makes no sense for many reasons:

  • debugging DSL the middleware whose debugger simply does not exist
  • The bug can be reproduced on production server
  • Too much overhead to set up debugger. Say I'm debugging component from other teams and developers and the technologies they use make configuring debugger very harder.


原创日期: 2013-01-31 四

2012年1月31日我写了一年成为Emacs高手(像神一样使用编辑器) (后文简称<一年>),到今天(2013年1月31日)正好一周年.











这是我的twittergoogle plus以及微博,也可以通过我的email<chenbin DOT sh AT GMAIL DOT COM>联系我.我也在新浪weibo.com上开通账号emacsguru.

Open url in Emacs with external browser

Here is some handy elisp function which use browse-url-generic to open the url in external browser (firefox, for example).

The key point is how to detect the url. If we are in w3m-mode, we will use the link under cursor or the URI of current web page. Or else, we will let browse-url-generic to detect the url.

(defun w3mext-open-link-or-image-or-url ()
  "Opens the current link or image or current page's uri or any url-like text under cursor in firefox."
  (let (url)
    (if (string= major-mode "w3m-mode")
        (setq url (or (w3m-anchor) (w3m-image) w3m-current-url)))
    (browse-url-generic (if url url (car (browse-url-interactive-arg "URL: "))))
(global-set-key (kbd "C-c b") 'w3mext-open-link-or-image-or-url)

To specify the external browser like firefox, add below code into ~/.emacs:

;; C-h v browse-url-generic-program RET to see the documentation

;; is-a-mac and linux is the boolean constants defined by me

(setq browse-url-generic-program (cond (is-a-mac "open") (linux (executable-find "firefox")) ))

Simplest workflow on email git commit in Emacs (No magit needed)

Sometimes I just want to email my trivial patch to the original author and forget it. In this case "github fork" or "git format-patch" is too heavy weight for me.

So here is the simplest workflow I can figure out:

  • Step 1, command "M-x vc-dir" whose hotkey is "C-x v d"
  • Step 2, command "M-x git-print-log" whose hotkey is "C-x v l"
  • Step 3, Move focus to the specific commit and run command "M-x log-view-diff" whose hotkey is "d".
  • Step 4, Yank the commit/diff
  • Step 5, Compose new email (command "M-x compose-mail" whose hotkey is "C-x m")
  • Step 6, Make sure the subject of email start with "[PATCH]". See this patch sumbit guide for reasons.
  • Step 7, Paste the content of commit/diff into email body.
  • Step 8, Send the email by command "M-x message-send-and-exit" whose hotkey is "C-c C-c"

Please note:

  • Step 1 is usually necessary unless you only need the diff of current file.
  • Step 2 and step 3 could be replaced with command "M-x vc-diff" or hotkey "C-x v =" if you want to email the diff of work directory.

Import Gmail contacts into BBDB

  • Go to, click the menu "More>>Export…>>vCard format (blah, blah …)".
  • Click "Export" button. Download the contacts.vcf.
  • Make sure bbdb-vcard.el installed.
  • In Emacs run "M-x bbdb-vcard-import-file" and input the full path of contacts.vcf
  • In Emacs run "M-x bbdb-save"
  • Remove contacts whose names are empty. These are Google Plus people inserted automatically by Gmail:

Run the command in shell:

# the orginal ~/.bbdb will be saved as ~/.bbdb.bak
sed -i.bak '/["" ""/d' ~/.bbdb

Search at both stackoverflow and google code in Emacs

Two programming sites are most valuable to me:
solution design and code prototype
google code search
code sample from real product

So I write some elisp code w3mext-hacker-search to automate the workflow.

Copy the into ~/.emacs and you can use hotkey "C-c ; s" to open search results in external browser (firefox, for example):

; external browser should be firefox
(setq browse-url-generic-program
       (is-a-mac "open")
       (linux (executable-find "firefox"))

;; use external browser to search

(defun w3mext-hacker-search () "search word under cursor in google code search and" (interactive) (require 'w3m) (let ((keyword (w3m-url-encode-string (thing-at-point 'symbol)))) (browse-url-generic (concat "" keyword)) (browse-url-generic (concat "" keyword "" ))) )

(add-hook 'prog-mode-hook '( lambda () (local-set-key (kbd "C-c ; s") 'w3mext-hacker-search)) )

Toggle http proxy in emacs-w3m

emacs-w3m is a browser embedded in Emacs. It can handle all my basic web surfing needs.

For some reason, I need switch my http proxy frequently when accessing the internet in China. So I need figure out a easy way doing this.

It turns out all I need to do is to set/unset the environment variable "http_proxy" in elisp code. Restarting the w3m session after change the environment variable is not needed at all.

Here is my code:

(defun toggle-env-http-proxy ()
  "set/unset the environment variable http_proxy which w3m uses"
  (let ((proxy ""))
    (if (string= (getenv "http_proxy") proxy)
        ;; clear the proxy
          (setenv "http_proxy" "")
          (message "env http_proxy is empty now")
      ;; set the proxy
      (setenv "http_proxy" proxy)
      (message "env http_proxy is %s now" proxy)

Use POPFile at Linux

CREATED: <2012-12-28>

UPDATED: <2017-03-12 Sun>

POPFile automatically sorts emails.

1 Install POPFile

2 Install third party packages


cpan DBD::SQLite DBI Date::Format Date::Parse HTML::Tagset HTML::Template IO::Socket::SSL Net::IDN::Encode Mozilla::CA

When being asked by cpan, say you prefer installing local lib.

This is my cpan setup,

$CPAN::Config = {
  'applypatch' => q[],
  'auto_commit' => q[0],
  'build_cache' => q[100],
  'build_dir' => q[/home/cb/.cpan/build],
  'build_dir_reuse' => q[0],
  'build_requires_install_policy' => q[yes],
  'bzip2' => q[/bin/bzip2],
  'cache_metadata' => q[1],
  'check_sigs' => q[0],
  'colorize_output' => q[0],
  'commandnumber_in_prompt' => q[1],
  'connect_to_internet_ok' => q[1],
  'cpan_home' => q[/home/cb/.cpan],
  'ftp_passive' => q[1],
  'ftp_proxy' => q[],
  'getcwd' => q[cwd],
  'gpg' => q[/usr/bin/gpg],
  'gzip' => q[/bin/gzip],
  'halt_on_failure' => q[0],
  'histfile' => q[/home/cb/.cpan/histfile],
  'histsize' => q[100],
  'http_proxy' => q[],
  'inactivity_timeout' => q[0],
  'index_expire' => q[90],
  'inhibit_startup_message' => q[0],
  'keep_source_where' => q[/home/cb/.cpan/sources],
  'load_module_verbosity' => q[none],
  'make' => q[/usr/bin/make],
  'make_arg' => q[],
  'make_install_make_command' => q[/usr/bin/make],
  'mbuild_arg' => q[--install-dirs site],
  'mbuild_install_arg' => q[./Build],
  'mbuild_install_build_command' => q[./Build],
  'mbuildpl_arg' => q[--installdirs site],
  'no_proxy' => q[],
  'pager' => q[/usr/bin/less],
  'patch' => q[/usr/bin/patch],
  'perl5lib_verbosity' => q[none],
  'prefer_external_tar' => q[1],
  'prefer_installer' => q[MB],
  'prefs_dir' => q[/home/cb/.cpan/prefs],
  'prerequisites_policy' => q[follow],
  'recommends_policy' => q[1],
  'scan_cache' => q[atstart],
  'shell' => q[/bin/bash],
  'show_unparsable_versions' => q[0],
  'show_upload_date' => q[0],
  'show_zero_versions' => q[0],
  'suggests_policy' => q[0],
  'tar' => q[/bin/tar],
  'tar_verbosity' => q[none],
  'term_is_latin' => q[1],
  'term_ornaments' => q[1],
  'test_report' => q[0],
  'trust_test_report_history' => q[0],
  'unzip' => q[/usr/bin/unzip],
  'urllist' => [q[]],
  'use_prompt_default' => q[0],
  'use_sqlite' => q[0],
  'version_timeout' => q[15],
  'wget' => q[/usr/bin/wget],
  'yaml_load_code' => q[0],
  'yaml_module' => q[YAML],

cpan will append setup ~/.bashrc,

PATH="$HOME/perl5/bin${PATH:+:${PATH}}"; export PATH;
PERL5LIB="$HOME/perl5/lib/perl5${PERL5LIB:+:${PERL5LIB}}"; export PERL5LIB;
PERL_MB_OPT="--install_base \"$HOME/perl5\""; export PERL_MB_OPT;

Double check installed packages:

perl -MDBI -e 'print $MIME::DBI::VERSION'

If there is any error:

perl -V
rm -rf ~/perl5/*
cpan DBD::SQLite DBI Date::Format Date::Parse HTML::Tagset HTML::Template IO::Socket::SSL Net::IDN::Encode MOZILLA::CA

3 Setup

I only use IMAP. The purpose of tweak POP3 port is only to make the program executable without root permission.

See for details.

Run the below command to fix the root issue.

sed -i 's/pop3_port \+110/pop3_port 1110/g' ~/bin/popfile/popfile.cfg

Here is my popfile setup for Davmail.

Davmail is a gateway to convert Outlook/Exchange service to IMAP/POP3). It's required if and only if you use Microsoft's Exchange/Outlook.

For other email service, you DON'T need Davmail.

If you don't use Davmail and fetch mails directly, you'd better set imap_expunge 1 to fix Microsoft Office 365 has some issue.

Please note ssl is disabled in my setup because I'm running local Davmail Server. Or else, you need enable ssl.

bayes_bad_sqlite_version 4.0.0
bayes_corpus corpus
bayes_database popfile.db
bayes_dbconnect dbi:SQLite:dbname=$dbname
bayes_nihongo_parser kakasi
bayes_sqlite_journal_mode delete
bayes_sqlite_tweaks 4294967295
bayes_subject_mod_left [
bayes_subject_mod_pos 1
bayes_subject_mod_right ]
bayes_unclassified_weight 100
bayes_xpl_angle 0
config_pidcheck_interval 5
config_piddir ./
GLOBAL_debug 1
GLOBAL_last_update_check 1407715200
GLOBAL_message_cutoff 100000
GLOBAL_msgdir messages/
GLOBAL_ssl_verify_peer_certs 0
GLOBAL_timeout 60
GLOBAL_update_check 1
history_archive 0
history_archive_classes 0
history_archive_dir archive
history_history_days 2
html_cache_templates 0
html_column_characters 0
html_columns +inserted,+from,+to,-cc,+subject,-date,-size,+bucket
html_language English
html_last_reset Sat Dec  1 11:06:48 2012
html_local 0
html_page_size 20
html_password b6b3637136ad630eba43aa5ee7106780
html_port 8888
html_search_filter_highlight 0
html_send_stats 1
html_session_dividers 1
html_show_bucket_help 1
html_show_training_help 0
html_skin simplyblue
html_strict_templates 0
html_test_language 0
imap_bucket_folder_mappings job-->job-->geek-->geek-->business-->business-->ad-->ad-->unclassified-->INBOX-->work-->work-->
imap_enabled 1
imap_expunge 1
imap_hostname localhost
imap_login binc1
imap_password password1
imap_port 1143
imap_training_mode 0
imap_uidnexts work-->749-->job-->5914-->INBOX-->20736-->geek-->5009-->ad-->1296-->business-->15-->
imap_uidvalidities job-->98-->work-->107-->ad-->100-->business-->106-->geek-->99-->INBOX-->2-->
imap_update_interval 1000
imap_use_ssl 0
imap_watched_folders INBOX-->INBOX-->
logger_format default
logger_level 0
logger_logdir ./
nntp_enabled 0
nntp_force_fork 1
nntp_headtoo 0
nntp_local 1
nntp_port 119
nntp_separator :
nntp_socks_port 1080
nntp_welcome_string NNTP POPFile (v1.1.3) server ready
pop3_enabled 0
pop3_force_fork 1
pop3_local 1
pop3_port 1110
pop3_secure_port 110
pop3_separator :
pop3_socks_port 1080
pop3_toptoo 0
pop3_welcome_string POP3 POPFile (v1.1.3) server ready
smtp_chain_port 25
smtp_enabled 0
smtp_force_fork 1
smtp_local 1
smtp_port 25
smtp_socks_port 1080
smtp_welcome_string SMTP POPFile (v1.1.3) welcome
xmlrpc_enabled 0
xmlrpc_local 1
xmlrpc_port 8081

The only remaining issue is user name. If it contains "\", you should replace it with "\\" when inputting in Popfile!

4 Run the program

See for details.

cd ~/bin/popfile;perl

5 Start the POPFile automatically when bash login

Insert below code in ~/.bashrc:

OS_NAME=`uname -s`
if [ $OS_NAME == Linux ]; then
   # start popfile
   if [ -f $HOME/bin/popfile/ ]; then
      # @see
      pop_pid=`ps -ef | grep perl | grep | gawk '{print $2}'`
      if [ "${pop_pid}" = "" ] ; then
         cd $HOME/bin/popfile
         perl >> /dev/null 2>&1 &
      cd $HOME

6 Start the POPFile systemd service as a user (OPTIONAL)

My user name is cb. Put popfile.service in usr/lib/systemd/system. Then run `systemctl enable popfile` to install service. Run `systemctl start popfile` to start the service. My Linux distribution is ArchLinux.

here is content of popfile.service.

Description=POPFile (Automatic Email Classification) Service



7 Backup

Please backup popfile.cfg and popfile.db.

See for details.

8 Summary

  • Portable
  • No root privilege needed
  • No X windows needed. I can manage mails in remote shell

Emacs Lisp并不难学

作者:陈斌 (redguardtoo)

原创日期: 2012-11-30 五


我学的是Emacs Lisp(Emacs Lisp),开发环境也是Emacs.所以我举的例子都是只基于Elisp.























(+ 2 3 4)

所有的语法都是这样的前缀表达式(Polish Notation),很多人不习惯这样的语法,但是它有一些突出优点:

  1. 这样的语法做语法解析特别容易,所以第三方支持工具很容易开发. 在大规模系统开发时,这点很有用.例如,分析大型项目的源代码时,你能唯一依靠的grep和正则表达式,ELisp简单严格的语法使得正则表达式很好写.
  2. 实际编程时少打很多运算符号,这对于有实战经验的程序员是巨大的优点.如果你和我说什么重要的是思想和设计模式,打字速度不重要,那么菜鸟请走开.
  3. 最重要的优点是,这种语法相当于一种过滤机制,能够接受这种语法的人通常都是头脑比较开放思维敏捷的人.说到底产品开发的决定性因素是人,所以这个能过滤人的优点是决定性的.



How to use ctags with Emacs effectively

See for general usage of tags file. A file name of tags files is 'TAGS' by default. But in Emacs manual the 'tags file' is named 'tags table'. Either 'tags file' or 'tags table' or 'TAGS' is only different name for the same thing.

According wiki page, people usually use ctags to do two things,

  1. Code navigation
  2. Auto-complete/Intellisense

    In my opinion, ctags is OK for code navigation because it's integrated into Emacs well and ctags supports more programming language. But ctags only uses regular expression to analyze the code. So it's not as precise as professional tools like cscope or GNU Global. According to my own experience, ctags plus grep is actually good enough for code navigation in big enterprise projects with mixed environments. If you are among a few talented geeks who are developing Linux kenel in the most efficient way, you should use better tools like GNU Global. See the head up from Nick Alcock. His summary of the Pro/Con of GNU Global is great.

    Intellisense is a different story. For programming languages like Javascript, ctags provide some intellisense with is better than nothing. C++ is a more complex language which is a litter harder for ctags to handle unless you are not using those "advanced" features of C++.

    I found one missing piece from Emacswiki is the tip on how to manage tags file easily when the TAGS is built from some code of third party libraries (QT, wxWidgets, GTK, Boost, just name a few).

    My typical work flow is:

  3. Load the tags file for my own code.
  4. Load other tags files built from third party libraries related to my current task.
  5. Unload third party tags immediately if its not needed.

    The purpose to load tags files is to look up API easily. For example, I use C++ library wxWidgets to develop my application. I want to use its API called wxWindow::Maximize. I type 'M-x find-tag" and input the keyword "Maximize". So I can check the function definition and know what parameters I need fill in to use "Maximize".

    The reason to do the unload thing is to avoid function name confliction from some tags files. Emacswiki has a section "Choosing Among Multiple Tags for the Same Name" to solve this problem. But unloading is more convenient. In theory, it would be annoying if I need repeat load and unload the same tags files. In reality, it seldom happens because if I need work on Javascript (so I unload C++ related TAGS), I will usually keep working on Javascript until the end of the day.

Produce tags files for all the environments

For exmaple, I produce tags files of Library A for Mac and Linux. I put tags file from Mac at directory "/home/cb/tags/Library_A/mac" and file from Linux at "/home/cb/tags/Library_A/linux"

Use git and github to manage the tags files

So I can have copies of the tags files at github server and my local computers. That's also a part of my strategy to setup the development environment. My projects on different computers usually use same external library.

Emacswiki discusses how to update your tags file frequently because your own code are updated frequently. But the tags file from a big library like wxWidgets need not be updated to often because I only use limited old APIs in that library.

Write emacs lisp code to load/unload these tags files

Here is the code. In this example, if I need load tags file for wxWidgets, I call the function "add-wx-tags". If I need unload the tags file, I press "Ctrl-u" and call the same function "add-wx-tags". Since I use Smex, calling function doesn't mean pressing many keys.

; Set up tags built from third party libraries ===begin
; define tags alias like "wx-tags" here
(setq wx-tags (expand-file-name "~/tags/wx/osx/TAGS"))

; @see <Selecting a Tags Table> in Emacs manual for details.
; We only change the list "tags-table-list". It is documented officialy.
(defun insert-into-tags-table-list(e)
  (add-to-list 'tags-table-list e t)

(defun delete-from-tags-table-list (e)
  (setq tags-table-list (delete e tags-table-list))

; This is a sample command, all you need is copy/paste this template
; for other new commands
(defun add-wx-tags (&optional del)
  "Add or delete(C-u) wxWidgets tags into tags-table-list"
  (interactive "P")
  (let (mytags)
    ; here add your third party tags files
    ; Usually you need load/unload tags files combination in one command
    ; change below line to add them
    (setq mytags (list wx-tags))
    (if del (mapc 'delete-from-tags-table-list mytags)
      (mapc 'insert-into-tags-table-list mytags)
; === end

This solution only uses one standard variable "tags-table-list" in Emacs. So it will always work with any other Emacs plugins you install. And you can use all the old hotkeys and functions ("find-tag", for example) without any problem.

See Emacs manual for technical details.