The freedom to run the program, for any purpose (freedom 0). The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this. The freedom to redistribute copies so you can help your neighbor (freedom 2). The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this You are free to (1)study it, (2)redistribute it, and (3) modify it. 2. Why is Linux popular?
Why is it popular in academia? Bell Labs offered it to educational institutions at nominal cost. The schools, in turn, used it in their computer science programs, ensuring that computer science students became familiar with it. Because UNIX was such an advanced development system, the students became acclimated to a sophisticated programming environment. As these students graduated and went into industry, they expected to work in a similarly advanced environment. As more of them worked their way up the ladder in the commercial world, the UNIX operating system found its way into industry
The source code for the operating system is readily available so that students can understand more easily how GNU/Linux works and can modify the code further to understand its operation and change the way it works. 3. What are multiuser systems? Why are they successful? Sharing the computer’s power among many users and giving them the ability to share data and programs are central features of the system. a multiuser operating system allows many people to use all of the system resources almost simultaneously The use of costly resources can be maximized and the cost per user can be
minimized—the primary objectives of a multiuser operating system. 4. What is the Free Software Foundation/GNU? What is Linux? Which parts of the Linux operating system did each provide? Who else has helped build and refine this operating system? The Free Software Foundation (www. fsf. org) is the principal organizational sponsor of the GNU Project. GNU developed many of the tools, including the C compiler, that are part of the GNU/Linux Operating System Linux is the name of an operating system kernel developed by Linus Torvalds and expanded and improved by thousands of people on the Internet.
Torvalds’s kernel and GNU’s tools work together as the GNU/Linux Operating System 5. In which language is Linux written? What does the language have to do with the success of Linux? 95% is written in C. Because Linux is portable, it can be adapted (ported) to different machines and can meet special requirements. For example, Linux is used in embedded computers, such as the ones found in cellphones, PDAs, and the cable boxes on top of many 10 Chapter 1 Welcome to Linux and Mac OS X TVs. The file structure takes full advantage of large, fast hard disks.
Equally important, Linux was originally designed as a multiuser operating system—it was not modified to serve several users as an afterthought. Sharing the computer’s power among many users and giving them the ability to share data and programs are central features of the system 6. What is a utility program? otften reffered to as “commands” These utilities perform functions that are universally required by users. The sort utility, for example, puts lists (or groups of lists) in alphabetical or numerical order and can be used to sort lists by part number, last name, city, ZIP code, telephone number, age, size, cost, and so forth.
A utility (program), sometimes referred to as a command, is a program that performs a task that is frequently related to the operating system. A utility is simpler than an application program although there is no clear line separating the two 7. What is a shell? How does it work with the kernel? With the user? In a textual environment, the shell—the command interpreter—acts as an interface between you and the operating system. its the link between user and kernal to tell it what to do. or view what the kernal is doing. its the command line interface that accepts input from the user.
8. How can you use utility programs and a shell to create your own applications? Write a shell script, also called a shell program, or a batch file under DOS. A shell script is one or more command lines contained in a file. Make the file executable and give the name of the file as a command: The shell executes the commands in the file, as though you had typed each command individually 9. Why is the Linux filesystem referred to as hierarchical? The Linux filesystem provides a structure whereby files are arranged under directories, which are like folders or boxes.
Each directory has a name and can hold other files and directories. Directories, in turn, are arranged under other directories, and so forth, in a treelike organization. This structure helps users keep track of large numbers of files by grouping related files in directories. Each user has one primary directory and as many subdirectories as required 10. What is the difference between a multiprocessor and a multiprocessing system? multi processor is a computer that has more than one processor (processing units) and
multiprocessing system is the fact that it can process multiple tasks at the same time Multiprocessing is the use of more than one CPU in a computer system 11. Give an example of when you would want to use a multiprocessing system. Multiprocessing is the use of more than one CPU in a computer system so when you have more than one CPU you can take advantage of it. Multiprocessing sometimes refers to the execution of multiple concurrent software processes in a system as opposed to a single process at any one instant 12. Approximately how many people wrote Linux?
Why is this project unique? The Linux kernel was developed by Finnish undergraduate student Linus Torvalds The Linux operating system, which was developed through the cooperation of many, many people around the world, is a product of the Internet and is a free 13. What are the key terms of the GNU General Public License? The GPL says you have the right to copy, modify, and redistribute the code covered by the agreement When you redistribute the code, however, you must also distribute the same license with the code, thereby making the code and the license inseparable.