Core Questions
What is Linux?
Linux is an operating system based on UNIX, and was first introduced by Linus Torvalds. It is based on the Linux Kernel, and can run on different hardware platforms manufactured by Intel, MIPS, HP, IBM, SPARC and Motorola. Another popular element in Linux is its mascot, a penguin figure named Tux.
What is an operating system?
An operating system is a collection of software programs which control the allocation and usage of various hardware resources in the system. It is the first program to be loaded in the computer and it runs in the memory till the system is shut down
What are the functions of operating system?
The operating system controls and coordinates the use of hardware among the different processes and applications. It provides the various functionalities to the users. The following are the main job of operating system.
- Resource utilization
- Resource allocation
- Process management
- Memory management
- File management
- I/O management
- Device management
What is the difference between UNIX and LINUX?
Linux is an open source, free to use operating system widely used for computer hardware and software, game development, tablet PCS, mainframes etc. Unix is an operating system commonly used in internet servers ,workstations and PCs by Solaris, Intel, HP etc.
What is the advantage of open source?
Open source allows you to distribute your software, including source codes freely to anyone who is interested. People would then be able to add features and even debug and correct errors that are in the source code. They can even make it run better, and then redistribute these enhanced source code freely again. This eventually benefits everyone in the community.
What are the basic components of Linux?
Just like any other typical operating system, Linux has all of these components: kernel, shells and GUIs, system utilities, and application program. What makes Linux advantageous over other operating system is that every aspect comes with additional features and all codes for these are downloadable for free.
What does FSF mean?
The Free Software Foundation (FSF) was founded in 1983 along with its demonstration GNU project. Richard Stallman, an MIT professor, had worked as a student on projects where software was freely exchanged without copying or modifying stipulations. Why, he asked himself and others, should software users be prohibited from copying it for friends, looking at the source code and copying it, and redistributing the results? Taking this idea to the group level, Stallman and others created the FSF and set out to demonstrate that an entire operating system could be developed and shared freely. The result was the Unix-like GNU, which, in August 1996, became complete by adding a kernel. The "free" does not mean at no charge. The Free Software Foundation does charge an initial distribution price for GNU. "Free" refers to the use the person who acquires the software has with it. The Free Software Foundation believes that individuals and society would benefit from, and moreover have the right to study a program's source code to discover how it works, to make changes that enhance the program in some way, and to redistribute and even to sell improved versions to others as long as they in turn make their software free of reuse restrictions
What is kernel?
The kernel is the central module of an operating system (OS). It is the part of the operating system that loads first, and it remains in main memory. Because it stays in memory, it is important for the kernel to be as small as possible while still providing all the essential services required by other parts of the operating system and applications. The kernel code is usually loaded into a protected area of memory to prevent it from being overwritten by programs or other parts of the operating system.Typically, the kernel is responsible for memory management,process and task management, and disk management. The kernel connects the system hardware to the application software. Every operating system has a kernel. For example the Linux kernel is used numerous operating systems including Linux, FreeBSD, Android and others.
Different types of kernel?
Monolithic Kernels -> In this architecture of kernel, all the system services were packaged into a single system module which lead to poor maintainability and huge size of kernel.
Micro kernels -> They follow the modular approach of architecture. Maintainability became easier with this model as only the concerned module is to be altered and loaded for every function. This model also keeps a tab on the ever growing code size of the kernel.
Explain process?
A process is a program that is running and under execution.
What is shell?
The outermost layer of a program. Shell is another term for user interface .operating system and applications sometimes provide an alternative shell to make interaction with the program easier. For example, if the application is usually command driven, the shell might be a menu-driven system that translates the user's selections into the appropriate commands .Sometimes called command shell, a shell is the .command processor interface The command processor is the program that executes operating system commands. The shell, therefore, is the part of the command processor that accepts commands. After verifying that the commands are valid, the shell sends them to another part of the command processor to be executed
Different file types in Linux?
By default linux have only three types of file types.They are
1.Regular file (-)
2.Directory files (d)
3.Special files (This category is having 5 sub types in it.)
a.Block file(b)
b.Character device file(c)
c.Named pipe file or just a pipe file(p)
d.Symbolic link file(l)
e.Socket file(s)
What is CLI?
CLI is short for Command Line Interface. This interface allows user to type declarative commands to instruct the computer to perform operations. CLI offers an advantage in that there is greater flexibility. However, other users who are already accustom with using GUI find it difficult to remember commands including attributes that come with it.
What is GUI?
GUI, or Graphical User Interface, makes use of images and icons that users click and manipulate as a way of communicating with the computer. Instead of having to remember and type commands, the use of graphical elements makes it easier to interact with the system, as well as adding more attraction through images, icons and colors.
What are daemons?
Daemons are services that provide several functions that may not be available under the base operating system. Its main task is to listen for service request and at the same time to act on these requests. After the service is done, it is then disconnected and waits for further requests.
What are environmental variables?
Environmental variables are global settings that control the shell’s function as well as that of other Linux programs. Another common term for environmental variables is global shell variables.
What is LILO?
LILO is a boot loader for Linux. It is used mainly to load the Linux operating system into main memory so that it can begin its operations.
What is the importance of the GNU project?
This so-called Free software movement allows several advantages, such as the freedom to run programs for any purpose and freedom to study and modify a program to your needs. It also allows you to redistribute copies of a software to other people, as well as freedom to improve software and have it released to the public.
Does the Ctrl+Alt+Del key combination work on Linux?
Yes, it does. Just like Windows, you can use this key combination to perform a system restart. One difference is that you won’t be getting any confirmation message and therefore, reboot is immediate.