VIM - How to format and syntax highlight JSON file

Formatting

• Run this command in shell 
  sudo cpan JSON::XS

• Put this line to ~/.vimrc 
  map <leader>jt  <Esc>:%!json_xs -f json -t json-pretty<CR>
  

• When want to format JSON file press

  \jt

  
  
• credit : “tidify” a json in vim

Syntax highlighting

• Download json.vim form http://www.vim.org/scripts/script.php?script_id=1945 to ~/.vim/syntax/
• Put this line to ~/.vimrc

  au BufRead,BufNewFile *.json set filetype=json

• credit : Add JSON syntax highlighting in Vim on OS X
  

VIM - How to format Html source code

1. :filetype indent on
2. :set filetype=html
3. :set shiftwidth=n (n = indent size)
4. :set smartindent
5. gg=G (gg = top of file, = is a shortcut of re-tindent, G = botton of file)

For 1,3,4 , you can predefine at .vimrc. While editing Html file, just do 2 and 5

VIM - How to format JavaScript source code

1. Download this plugin jsbeautify
2. Copy it to $HOME/.vim/plugin/
3. In Vim, while you want to format JavaScript code, press \ff*

* From jsbeautify's document tells to press <leader>ff which in Vim <leader> by default is set to "\"

Singleton vs Class method

I want to tell you before go on through the detail that following article is based on Java. Different implemented language might not have the similar behavior.

Singleton or Class method ?

This topic might too old for some of you but I always was reminded to this issue when I was going to write some method just do some algorithms - take inputs, processing, return output.

We will find many discussions on this issue if we do googling. Below this are what I conclude those discussions for myself.

1. Singleton provides typing. You can subclassing or passing it around whatever you can do to an object-oriented instance you can do to Singleton object.
2. Singleton provides state which a lot of you may think it is disgusting.
3. Singleton provides lazy-initialization. You have not to have it on your memory until you are really want it.
4. You can have many instances of Singleton-type. Also can limit number of them. While you can not do this with Class method.

I'm going to update this if I find more distinction points

Shutdown Mac OS X with command line

I have founded that ordinary

$shutdown -p now

command line not enough to close Mac box. It doesn't turn the machine off.

After some googlings, I founded this The Command Line Junkie's Guide To Mac OS X,

which tell me that I can shut it down with command :

osascript -e 'tell application "Finder" to shut down'

Java thread stack size

Today, I have just known that there's an another interesting parameter to set to JVM. It is java thread stack size.

With too high thread stack size, it will effect to low number of thread JVM can create - see this experiment. Not enough memory for java thread (cause from too big stack size) will produce "java.lang.OutOfMemoryError: unable to create new native thread"

You can set java stack thread size by adding -XssnK to JVM argument where n stands for a wanted size.

Now, I am not sure what is the default java thread stack size. Someone tells it is 512Kb. Another one tells it is up to the platform. One thing is that it's vary between each java versions. However, there is a way to get it from your running JVM. I got this trick from Get thread stack size at runtime thanks to claudio. Note that this trick may work only with *nix family.

First, you have to know your target JVM's pid (process id). If your system has only one JVM running, it is easy to use 'ps' or top to find it. But if it has many, my often used approach is to use

jps -lv

and justify it from the informations provided. If the informations are equally the same, help yourself :P.

Now you have target JVM's pid.

Then run following command

jinfo -flag ThreadStackSize {PID}

The jvm's set thread stack size will show to you in Kb.

How to connect VPN via PPTP with Ubuntu

I had tried to connect to my office local network with my Karmic machine via PPTP protocol. I saw a VPN stuff when clicked 'Edit Connections' of NetworkManager Applet (normally on top left of you screen) but couldn't do anything to it. So I started googling and found below.

First, I had to install PPTP for NetworkManager

sudo apt-get install network-manager-pptp

Now, we can do setting PPTP VPN.

Just enter gateway, username and password your PPTP VPN will be now ready to work.

But for me, I want to go out to normal internet with my internet router not to go through my office network. I have to do something a bit.

In editing vpn, click on tab IPv4 setting -> Routes.

Enter ip(s) that want to use vpn and netmark.

You can leave another 2 columns, gateway and metric blank.

Thick in box "Use this connection only for resources on its network"

done.


Credit : VPN - Ubuntu Wiki, Howto configure PPTP VPN in Ubuntu Intrepid and Jaunty
Testing OS : Ubuntu 9.10 (Karmic Koala)