Updating Ubuntu Package Repositary

What is Repositary?

Repositories are servers which contain sets of packages. In other words Package Repositary is a database where informations about all the softwares available for Ubuntu is stored.
Software in Ubuntu's repository is divided into four categories or components - main, restricted, universe and multiverse.

• Main - The main component contains applications that are free software, can be freely redistributed and are fully supported by the Ubuntu team.
  
  
• Restricted - Supported software that is not available under a completely free license and also not complete support may not be available.
  
  
• Universe - The universe component is a snapshot of the free, open-source, and Linux world. It houses almost every piece of open-source software, all built from a range of public sources. Canonical does not provide a guarantee of regular security updates for software in the universe component
  
  
• Multiverse - The multiverse component contains software that is not free, which means the licensing requirements of this software do not meet the Ubuntu main component licence policy. The onus is on you to verify your rights to use this software and comply with the licensing terms of the copyright holder. This software is not supported and usually cannot be fixed or updated.  Use it at your own risk.

Why updating is necessary?

There are many situations or reasons where you need to update Ubuntu software repositary. One common reason is that, by updating the repositary, you can have a quick access to latest softwares available for Ubuntu. Also in some situations the Ubuntu software repositary may get deleted. When the software repositary is erased you can't install the required softwares from terminal. So in that case to put everything up, you have to update your repositary.

So how to update from Terminal?

It is very easy to update your software repositary through terminal. Just follow the steps.

1. Open the terminal.
2. You should have a internet connection to update your repositary.
3. Then in the terminal enter the command apt-get update
4. Then the 'apt-get' command will ask you for the admin password.
5. After entering the admin password the update process starts. 

Downloading a whole website via Terminal in Ubuntu

In this tutorial i am going to explain how to download a whole website into your computer. After doing the steps i explained below you can use the downloaded website offline!!.  That also without any third-party software.
To download the website and to convert it to offline edition, i am going to use a commandline utility called 'wget'.

These are the steps to download an offline edition of any website.
  1. Open the terminal
  2. Now enter the following command.
                        wget --mirror -p --convert-links -p destination_path website_URL
 
Now i will tell what those words mean.

• wget - This is the utility which does all this great stuff
• --mirror - Turns on options suitable for mirroring
• -p - Instructs to download all the files required to the page to load properly
• --convert-links - Converts all the links in the each web pages to the offline path so that offline navigation between pages is possible.
• destination_path - This is the local path where the downloaded files should be stored. When you are executing the actual command, you have to replace this by a local path. (i.e. Path to any folder that exist in your computer.)
• website_URL - This is the web site address.

So now you know the general command. If you want an example here it is.
                    wget --mirror -p --convert-links -p /home/user/Documents http://en.wikipedia.org
The above command will download Wikipedia frontpage along with the pages linked from the frontpage and all the downloaded files will be stored in the Documents/en.wikipedia.org folder.