The most efficient way to `git add` files in dired-mode

Add following code into your .emacs, then use "/" to execute git command on your marked files in dired-mode:

(defun diredext-exec-git-command-in-shell (command &optional arg file-list)
  "Run a shell command git COMMAND' on the marked files.
if no files marked, always operate on current line in dired-mode

" (interactive (let ((files (dired-get-marked-files t current-prefix-arg))) (list ;; Want to give feedback whether this file or marked files are used: (dired-read-shell-command "git command on %s: " current-prefix-arg files) current-prefix-arg files))) (unless (string-match "[?][ \t]\'" command) (setq command (concat command " *"))) (setq command (concat "git " command)) (dired-do-shell-command command arg file-list) (message command))

(eval-after-load 'dired '(define-key dired-mode-map "/" 'diredext-exec-git-command-in-shell))

For example, say you set the alias "a" for git command "add" in your $HOME/.gitconfig.

In order to git add files, you marked files in dired-mode and press "/", then press "a". The command git a(dd) will be executed.

The reason to use git in dired-mode is simple. I'm working for some big enterprise application. You know the enterprise guys have the tendency to create lots of small modules/files for one feature. So I need do lots of cp files somewhere and git add files things these days.

Thanks all the Emacs geeks on the Google+ who enlighten me.

How to split album into different flac and tag them under Gentoo Linux

Install CLI tools

# mac to support ape
sudo USE="alac flac mac shorten sox wavpack" emerge media-sound/shntool
sudo emerge cuetools

Download script

See for the source of bash script.

Here is the full content of the bash script:

# split image file (flac, ape, wav, etc.) according to cue-file
if [ -f "$1" ]; then
    for cuefile in *.cue; do
        i=$(($i + 1))
    if [ $i -eq 1 ]; then
        # precies 1 cuesheet gevonden
        if grep -q "INDEX 01 00:00:00" *.cue ; then
            nice shntool split -t "%n %t" -f *.cue "$1"
            echo "The first track has a pre-gap. Shntool will cut that off and put it in a seperate file."
            echo "You don't want that. Please modify the cuesheet from:"
            grep -m1 "INDEX 00" *.cue
            grep -m1 "INDEX 01" *.cue
            echo "to:"
            echo "    INDEX 01 00:00:00"
            exit 1
    elif [ $i -eq 0 ]; then
        echo "No cuesheet found in the current directory."
        exit 1
    elif [ $i -gt 1 ]; then
        echo "$i cuesheets found in the current directory. Please remove the superfluous cuesheets."
        exit 1
    echo "Split image file (flac, ape, wav, etc.) according to cue-file."
    echo "Output files are in FLAC."
    echo "Usage: `basename $0` <image-file>"
    exit 1

album=`grep -m 1 TITLE *.cue | cut -d\" -f2`
artist=`grep -m 1 PERFORMER *.cue | cut -d\" -f2`

for file in [0-9]*.wav; do
    echo "Encoding $file"

    if [[ ${file:0:1} == 0 ]] ; then
    title=`echo ${file:2} | sed -e "s/.wav$//"`

    nice flac -s -T "artist=$artist" -T "album=$album" -T "title=$title" \
    -T "tracknumber=$tracknr" "$file" && rm "$file"

Put the script somewhere and name it to cue2flac

Start conversion

# convert the ape to corresponding wav file, for example, "a.ape" is converted to "a.ape.wav"
find . -name '*.ape'|xargs -I {} ffmpeg -i {} {}.wav
# split wav and convert it to flac, make sure the *.cue exists in current directory
cue2flac a.ape.wav
# do the cleaning (OPTIONAL)
rm *.ape *.wav

The minimum .emacs for debug purpose

I've installed more than 100 emacs plugins.

Here is my minimum .emacs to test plugins,

(show-paren-mode 1)
(eval-when-compile (require 'cl))

;; test elisps download from internet here
(setq test-elisp-dir "~/test-elisp/")
(if (not (file-exists-p (expand-file-name test-elisp-dir)))
    (make-directory (expand-file-name test-elisp-dir)))

(setq load-path
        (loop for dir in (directory-files test-elisp-dir)
              unless (string-match "^\\." dir)
              collecting (expand-file-name (concat test-elisp-dir dir)))

;; package repositories
(require 'package)
(add-to-list 'package-archives '("marmalade" .  "") t)
(add-to-list 'package-archives '("melpa" . "") t)

;; ==== put your code below this line!

The code is straight forward. I scan any sub-directories in ~/test-elisp and add them into load-path.

I've uploaded the .emacs to Dropbox, so you can use one bash liner to download it:

cd ~/;wget;mkdir -p ~/test-elisp;

How to use keyboard to navigate

Here is the detailed steps,

  1. Install keysnail (a firefox addon)
  2. Install HoK (no less than version 1.3.9) through keysnail
  3. Add below code into .keysnail.js
/* HoK /
key.setViewKey('e', function (aEvent, aArg) {
        ext.exec("hok-start-foreground-mode", aArg);
}, 'Hok - Foreground hint mode', true);

key.setViewKey('E', function (aEvent, aArg) { ext.exec("hok-start-background-mode", aArg); }, 'HoK - Background hint mode', true);

key.setViewKey(';', function (aEvent, aArg) { ext.exec("hok-start-extended-mode", aArg); }, 'HoK - Extented hint mode', true);

key.setViewKey(['C-c', 'C-e'], function (aEvent, aArg) { ext.exec("hok-start-continuous-mode", aArg); }, 'Start continuous HaH', true);

hook.addToHook('PluginLoaded', function () { if (!plugins.hok) return;

/ HoK 1.3.9+ requried / plugins.hok.pOptions.selector = plugins.hok.pOptions.selector / feedly / + ", [data-uri]" + ", [data-selector-toggle]" + ", [data-page-action]" + ", [data-app-action]" ; });

  1. Restart Firefox, logged into and press hot key "e"
  2. Enjoy!

How to use yasnippets to produce email templates in Emacs

CREATED: <2013-05-01 Wed>

UPDATED: <2015-11-13 Fri>


As a freelancer, I need reply agent's email frequently.

So I have several issues to resolve:

  • Avoid writing multiple mails with similar content
  • Avoid attaching same resume again and again
  • Get the agent's name right. This is not easy since I'm living in Sydney


Yasnippet is the best solution for email templates because you can embed Lisp code in the template.


I publicize my .emacs.d at github. But email templates are my private stuff. So I place them in different location.

That's why I place templates at ~/my-yasnippets/message-mode/.

Here is a sample template to reply my agents (jobok.yasnippet):

# -*- mode: snippet -*-
# name: email for OK job
# key: jobok
# --
Hi ${1:`(my-yas-get-first-name-from-to-field)`},

Thank you very much for providing me this great opportunity.

Unfortunately I'm occupied now and will not consider new job for the time being.

Currently I'm working for ${2:COMPANY_NAME} as a contract developer. However, the
contract will be over ${3:END_OF_CONTRACT} and I will be available then.

So keep in touch.

Attached is my latest CV.

<#part type="application/msword" filename="~/org/cv/cv.doc" disposition=attachment description=resume>

`(my-yas-get-first-name-from-to-field)` is a Lisp function embedded in the snippet.

It will automatically fetch the first name of agent,

(defun my-yas-get-first-name-from-to-field ()
  (let ((rlt "AGENT_NAME") str)
      (goto-char (point-min))
      ;; first line in email could be some hidden line containing NO to field
      (setq str (buffer-substring-no-properties (point-min) (point-max))))
    (if (string-match "^To: \"\\([^ ,]+\\)" str)
        (setq rlt (match-string 1 str)))
    (message "rlt=%s" rlt)

Emacs setup

Add following code into .emacs to make yasnippet load the emacs templates:

(require 'yasnippet)
(setq my-yasnippets (expand-file-name "~/my-yasnippets"))
(if (and  (file-exists-p my-yasnippets) (not (member my-yasnippets yas-snippet-dirs)))
    (add-to-list 'yas-snippet-dirs my-yasnippets))
;; yasnippet setup code should be AFTER
(yas-global-mode 1)

Make Emacs support auto-completion for CMake

Easy. You only install company-mode and company-cmake.el according to the documentation HERE.

company-cmake.el is written by me. I'm in the process of signing necessary copyright papers to make it part of company-mode. I was told the process could take one month because I'm deal with GNU foundation. So please be patient.

Anyway, you can use company-cmake.el right now with company-mode without any problem.

Please note I only tested this plugin with cmake 2.8.

Here is screen shot:

UPDATED (12th Jan, 2014): Legal procedure is done. Now company-cmake.el is officially part of company-mode since version 0.6.12.

So all you need to do is install latest company-mode, no other set up required!

Convert multiple line into one big string in Emacs

This command converts selected region in Emacs into one string and put it into the kill ring.

Why I need this command? I'm doing some web developement now. I've got a javascript API whose parameter is a string in html syntax. I write that beautifully indented multiple lines string in html editor to make sure the string is correct. Then I convert the multiple lines string into one string without line breaks so that I can paste the one line string into my javascript code.

In certain situation, this method actually makes code more readable.

Here is code you can paste into your .emacs:

(defun strip-convert-lines-into-one-big-string (beg end)
"strip and convert selected lines into one big string which is copied into kill ring.
When transient-mark-mode is enabled, if no region is active then only the
current line is acted upon.

If the region begins or ends in the middle of a line, that entire line is
copied, even if the region is narrowed to the middle of a line.

Current position is preserved."
  (interactive "r")
  (let (str (orig-pos (point-marker)))
    (when (and transient-mark-mode (not (use-region-p)))
      (setq beg (line-beginning-position)
            end (line-beginning-position 2)))

    (goto-char beg)
    (setq beg (line-beginning-position))
    (goto-char end)
    (unless (= (point) (line-beginning-position))
      (setq end (line-beginning-position 2)))

    (goto-char beg)
    (setq str (replace-regexp-in-string "[ \t]*\n" "" (replace-regexp-in-string "^[ \t]+" "" (buffer-substring-no-properties beg end))))
    ;; (message "str=%s" str)
    (kill-new str)
    (goto-char orig-pos)))
(global-set-key (kbd "C-c C-y") 'strip-convert-lines-into-one-big-string)

How to manage my software configuration at github


Here is the situation:

  • I've set up a repository at github to store my configuration of specifi software.
  • I synchronize the configuration with several computers
  • All these computers belongs to me only.

My issue is after using git pull/push for some time. My commit history looks not linear.


Simple. I need use git pull –rebase origin master instead of git pull origin master

Rebase will usually rewrite my commit history at your local branch. It's totally fine because I won't share the software configuration on my local computer. If I want to share my configuration, I will use the public url at github.

My work flow to debug emacs plugin

Author: Chen Bin < AT gmail DOT com> Created: 2013-03-30 Sat

This is my quick guide on how to start debugging elisp. It's written for developers who are already experienced on debugging program but too lazy to read the Edebug manual.

The most critical set up for the debugging is to set the hot key "C-h C-f" to the command "find-function" so you can jump the definition of the function easily.

(global-set-key (kbd "C-h C-f") 'find-function)

Here is my workflow.

start the debugging

  • Jump to the definition of the command (The hot key is "C-h C-f", as I mentioned before).
  • Run "M-x edebug-defun" . This will set the breakpoint into the entry of the command. BTW, I run "M-x eval-defun" in the function body to undo "edebug-defun".
  • Run the command to be debugged from Emacs
  • Press "space" key (M-x edebug-step-mode) to debug the program step by step
  • Watch the value of expression in the mini-buffer when you press "space" key

basic debug operation

  • Press "i" key (M-x edebug-step-in) to step in
  • Press "o" key (M-x edebug-step-out) to step out
  • Press "b" key (M-x edebug-set-breakpoint) to set the break point (press "u" key unset break point. I don't use this though)
  • Press "g" key (M-x edebug-go-mode) to continue
  • Press "h" key (M-x edebug-goto-here) to proceed until at the current line

Watch the variable and functions

  • Press "e" key (M-x edebug-eval-expression) to run the expression in the context outside of Edebug. Basically it means print a variable's value. Very useful.
  • Press "C-x C-e" key (M-x edebug-eval-last-sexp) in the context outside of Edebug. Similar to "e", useful if you are lazy to input the expression manually.

"Outside of Edebug" means you are only watching the variable's value. You will NOT change the status of program being debugged

Set the variable

  • Press "M-:" key (M-x eval-expression) to evaluate the expression in the context of Edebug itself.

I usually don't do this. It's not my debugging style.

Use screen/rtorrent/cronie to manage torrent client

`man rtorrent` for the keybindings:

  • `Enter` to input magnet from piratebay manually
  • `C-s` to start download
  • `C-d` to delete

For ArchLinux only:

Prepare directory

mkdir -p ~/bt/{session,finished,torrent}


sudo pacman -S cronie
sudo systemctl enable cronie
sudo systemctl start cronie

Add cron task to start and stop rtorrent service

crontab -e #add cron task as current user

The default editor will be open, input below content:

#start rtorrent sesssion at 1am
0 1 * * * /usr/bin/screen -fa -d -m -S torrent /usr/bin/rtorrent
# kill it at  9am
0 10 * * * /usr/bin/screen -S torrent -X quit