Upgrade Debian 3.1(sarge) to 4.0(etch)

It look like that to upgrade from Debian 3.1 to 4.0 should be fairly easy; however, the truth is that you will somehow trap by "libc6" loop. Here is a note to solve the problem.

1. Update 3.1 as best as possible. Modified the /etc/apt/sources.list
   

   #OldStable
   #deb http://security.debian.org/ lenny/updates main contrib non-free
   #deb http://ftp.us.debian.org/debian/ oldstable main contrib non-free

   
   sudo apt-get update

sudo apt-get upgrade
   


2. Switch to the etch sources, and update the kernel.
   

   #etch
   deb http://security.debian.org/ etch/updates main contrib non-free
   deb http://ftp.us.debian.org/debian/ etch main contrib non-free

   
   sudo apt-get update

sudo apt-get install linux-image-2.6.18-6-686
   


3. Pre-Processing
   apt-get install locales
   
   Make sure we handle all the dependency issue:
   apt-get install -f
   


4. Install the kernel.
   
   sudo apt-get install linux-image...
   


5. Update Grub by running: update-grub
   
   Edit /boot/grub/menu.lst, set the Default to correct kernel
   


6. Edit the tow links to the right kernel:

   /boot/initrd.img initrd.img -> initrd.img-2.6.8-3-686-smp
   /boot/vmlinuz  -> vmlinuz-2.6.8-3-686-smp

   , and then Reboot

Install Postfix on Ubuntu

A step by step instruction to install a postfix server on ubuntu 8.10:

1. Install package.
   sudo apt-get install postfix
   
   
   
   1. type of mail configuration: Internet Site
   
   
   2. enter your domain name: e.g. not.exist.edu (You have to register a domain name first) Free Register
   
   
   
   


2. Install mail utilities if you want to send a email through command line.
   sudo apt-get install mailutils
   


3. Write a testing email.
   echo testing_message | mail -s Subject_Not_Important youremail@some.domain.name
   You should get your email in a second. If not, check your SPAM filter/box.
   


4. By default, the log files locate at /var/log
   ls -l /var/log | grep mail
   Check log files if you encounter any errors.
   

How to move mysql datadir to new location

By default the mysql install the datadir at /var/lib/mysql. Unfortunately, people usually did partition their hard disk, or buy a new hard drive later. In such a case, you would like to move the *huge* datadir to another disk to both boost the speed by parallel in I/O and utilize space smartly. Here's what you should do:

1. Stop your mysql service.
   sudo /etc/init.d/mysql stop


2. Copying all files from old location to new location and preserver the ownership and timestamp information.
   sudo cp -r -p /var/lib/mysql /newlocation/


3. Update your mysql configuration file:
   sudo vim /etc/mysql/my.cnf
   

   datadir     = /newlocation/mysql #old: /var/lib/mysql
   



4. Update the second configuration file for apparmor:
   

     /newlocation/mysql/ r, #/var/lib/mysql/ r,
     /newlocation/mysql/** rwk, #/var/lib/mysql/** rwk,



5. (Optional) Rename the old folder to prevent confusing.
   sudo mv /var/lib/mysql /var/lib/mysql.bak


6. Restart your apparmor & mysql service.
   sudo /etc/init.d/apparmor reload
sudo /etc/init.d/mysql start


7. Delete the old location
   sudo rm -rf /var/lib/mysql.bak

Recursively download entire website from a ftp

The easiest way is the following command:
wget -r ftp://user:password @domain.name here

The only problem is that this method doesn't support "resume" function :)

Intall Python 3 on Ubuntu

0. Install related packages:
sudo apt-get install build-essential libncursesw5-dev libreadline5-dev libssl-dev libgdbm-dev libbz2-dev libc6-dev libsqlite3-dev tk-dev g++ gcc

1. Download the file to /tmp:
cd /tmp
wget http://www.python.org/ftp/python/3.1.1/Python-3.1.1.tgz

2. Unzip the tar zip file:
tar xzvf Python-3.1.1.tgz

3. Run configuration command ./configure
* In case you encounter some problem, install build-essential

4. make (optional)

5. Install the program to system:
sudo make install

Appending to Your Python Path

Question:

How do you append directories to your Python path?

Answer:

Your path (i.e. the list of directories Python goes through to search for modules and files) is stored in the path attribute of the sys module. Since path is a list, you can use the append method to add new directories to the path.

For instance, to add the directory /home/me/mypy to the path, just do:

    import sys
    sys.path.append("/home/me/mypy") 

src: Here

wget with proxy

As a researcher, we often need to crawl the web pages and save a dump in local disk for future use. However, sometimes we use a proxy to connect a specific website for security concerns or performance issue. There are two ways to assign this job, the first method:

• Create a ~/.wgetrc file: This file can be used as a configuration file for wget command.
  

  http_proxy=<your http proxy>

  
  Reference: wget manual
  


• Add a environment variable to your ~/.bashrc.

  export http_proxy="...url..."

  
  
  

Either way works well, but how about a proxy through socks proxy?

sorry... I cannot find a solution yet