CUPS - Print Server

The primary mechanism for Ubuntu printing and print services is the Common UNIX Printing System (CUPS). This printing system is a freely available, portable printing layer which has become the new standard for printing in most Linux distributions.
CUPS manages print jobs and queues and provides network printing using the standard Internet Printing Protocol (IPP), while offering support for a very large range of printers, from dot-matrix to laser and many in between. CUPS also supports PostScript Printer Description (PPD) and auto-detection of network printers, and features a simple web-based configuration and administration tool.

Installation

sudo apt-get install cups

Install Adobe reader

 The correct way to install Adobe reader is:

su

rpm -ivh http://linuxdownload.adobe.com/adobe-release/adobe-release-i386-1.0-1.noarch.rpm

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-adobe-linux

yum -y install nspluginwrapper.i686 AdobeReader_enu

Difference between Hard Link and Soft Link in unix

Hard link:

• Hard Link is a mirror copy of the original file.
• Hard links share the same inode.
• Any changes made to the original or Hard linked file will reflect the other.
• Even if you delete any one of the files, nothing will happen to the other hard links.
• But soft link which points to deleted hard link become a dangling soft link.
• You can't link a directory even within the same file system.
• Hard links can't cross file systems.

Soft link( also called symbolic link):  

• Soft Link is a symbolic link to the original file.(more like windows shortcuts)
• Soft Links will have a different Inode value.
• Any changes made to the soft link will reflect the original file and its hard links.
• A soft link points to the original file. If you delete the original file, the soft link fails. It would become dangling symbolic link.
• If you delete the soft link, nothing will happen.
• You can link a directory using soft link on same file system and also on other file system.
• Soft links can cross file systems

Search Google from Linux O.S commandline

  You can search google for a result even from your linux command line.

curl -A Mozilla http://www.google.com/search?q=Linux |html2text -width 80

You need to install CURL and HTML2TEXT in your box.

apt-get install curl html2text ( Ubuntu)
yum install curl html2text (Fedora )

How to create symbolic link in unix or linux

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To create a symbolic link in Unix or Linux, at the shell prompt, enter the following command:

tsusilkumar# ln -s {target-filename} {symbolic-filename}

For example create softlink for /webroot/home/httpd/test.com/index.php as 

/home/surya/index.php,
enter the following command:

#ln -s /webroot/home/httpd/test.com/index.php /home/surya/index.php

How can I install VLC player in Fedora Linux?

                  step1 : To install VLC on fedora:

•                             Type in the terminal : 

• •                       su - 

     Step2 : Download below link

    yum localinstall --nogpgcheck http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-stable.noarch.rpm http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-stable.noarch.rpm

     Step 3:

            Then type:
    

    •                yum repolist

       

     step 4 :

              Update VLC:

    •                yum update

      step 5 : 

          install vlc 

                     yum install vlc

Linux_distributions

 Linux_distributions

KERNEL

A kernel is a central component of an operating system. It acts as an interface between the user applications and the hardware. The sole aim of the kernel is to manage the communication between the software (user level applications) and the hardware (CPU, disk memory etc). The main tasks of the kernel are :

• Process management
• Device management
• Memory management
• Interrupt handling
• I/O communication
• File system...etc..

Difference between kernel & O.S

The kernel is part of the operating system and closer to the hardware it provides low level services like:

• device driver
• process management
• memory management
• system calls

An operating system also includes applications like the user interface (shell,gui,tools and services).

So the ultimate difference is ,

1. Kernel is responsible for Hardware level interactions at some specific range.But the OS is like hardware level interaction with full scope of computer.
2. Kernel triggers SystemCalls to intimate os that this resource is available at this point of time.OS is responsible to handle that system calls in order to utilize the resource.

GNU (General Public License)

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The GNU General Public License (GNU GPL or GPL) is the most widely used software license, which guarantees endusers the freedoms to use, study, share (copy), and modify the software. 

                  Software that ensures these freedom-rights, is called free software. The license was originally written by Richard Stallman of the Free Software Foundation (FSF) for the GNU project.The GPL license can be used by anyone, to ensure the enduser's freedom rights (use, share, study, modify).

                It is the first copyleft license for general use. Copyleft means that derived works can only be distributed under the same license terms. Under this philosophy, the GPL grants the recipients of a computer program the freedom-rights of the free software definition and uses copyleft to ensure the freedoms are preserved, even when the work is changed or added to. This is in distinction to permissive free software licenses . (source wikipedia)

History of Linux

History of Linux  :


History of Linux began in 1991 with a personal project by a Finnish student, Linus Torvalds, to create a new operating system kernel. Since then, the resulting Linux kernel has been marked by constant growth throughout its history. It has grown from a small number of C files under a license prohibiting commercial distribution to its state in 2009 of over 370 megabytes of source under the GNU General Public License .

                           Since then, the resulting Linux kernel has been marked by constant growth throughout its history. Since the initial release of its source code in 1991. 

The term Linux properly refers to just the operating system kernel itself. However, in popular parlance ‘Linux’ is used to refer to a complete Linux Distribution which includes GUI components and many other utilities, many of which are supplied by the GNU Project. Android, for example .

                        The development of Linux is one of the most prominent examples of free and open source software collaboration: the underlying source code may be used, modified, and distributed—commercially or non-commercially—by anyone under licenses such as the GNU General Public License. Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Some popular mainstream Linux distributions