Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds.
Linux was originally developed as a free operating system for Intel x86-based personal computers. It has since been ported to more computer hardware platforms than any other operating system. It is a leading operating system on servers and other big iron systems such as mainframe computers and supercomputers: more than 90% of today's top 500 supercomputers run some variant of Linux, including the 10 fastest. Linux also runs on embedded systems (devices where the operating system is typically built into the firmware and highly tailored to the system) such as mobile phones, tablet computers, network routers, televisions and video game consoles; the Android system in wide use on mobile devices is built on the Linux kernel.
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 include Debian (and its derivatives such as Ubuntu), Fedora and openSUSE
Linux is an operating system kernel, and UNIX is a certification for operating systems. The UNIX standard evolved from the original Unix system developed at Bell Labs. After Unix System V, it ceased to be developed as a single operating system, and was instead developed by various competing companies, such as Solaris (from Sun Microsystems), AIX (from IBM), HP-UX (from Hewlett-Packard), and IRIX (from Silicon Graphics). UNIX is a specification for baseline interoperability between these systems, even though there are many major architectural differences between them. Linux has never been certified as being a version of UNIX, so it is described as being "Unix-like." A comprehensive list of differences between Linux and "UNIX" isn't possible, because there are several completely different "UNIX" systems.
Linux is a multiuser, multitask GUI based open source operating system developed by Linus Torvalds Torvalds has invited the community to enhance the Linux kernel and thousands of system programmers worked on to enhance.
Prior to Linux, there is UNIX. The desktop work stations from various companies were based on UNIX. Later a numerous companies entered and each one of them had their own UNIX version. As the proprietary authority is owned by each company and the lack of central authority weaken UNIX. As Linux is free and runs on any PC platform it gained the popularity very quickly. The following are few more reasons for its popularity:
- People who are familiar with UNIX can work on Linux with ease and comfort.
- People who want great control over network security and on operating system
LILO stands for Linux Loader which is a bootstrap program. LILO is a code snippet which loads PC BIOS into the main memory at the time of starting the computer system. LILO handles the following tasks:
-Locating Linux kernel
-Identifying other supporting programs and loading them in the memory
The selection of various kernel images and boot routines is supported by LILO. For this reason, LILO is known as boot manager.
Home Directory: Every user will have one home directory and will have complete control over it. On login, home is the default working directory for the user. It contains the configuration files and responsible for login and logout of the user.
Working directory: The directory in which the user is working currently is known as working directory. The home may also be the working directory, if the user is working in it.