Chapter 1: What is Linux? 1.1. Basic and applied software The working computer has two parts roughly separately. It is hardware and software. Hardware indicates the machine of the computer. Software indicates the program that operates with hardware. It is just the same as the relation of the main body of the game machine (= hardware) and the software of the game (= software). There are the main two kinds in software. It is basic software and applied software. Basic software is called Operating System(OS) and applied software is called application software. Applied software works on basic software.
1.1.1. Role of OS Extreme speaking, basic software is "Nothing is done by itself. " It offers only very basic functions. For instance, in applied software of the window method used, there are menu, the dialogs to warn, and buttons for the confirmation. In the preparation of applied each software for these functions, making applied software becomes it very much.It is one of the big roles of basic software to offer the function that can be used by applied software commonly. The function "Resource management" is provided also in the rest. "Resource" in this case means functions and abilities that the computer can be offered. For instance, the software of the word processor and the spread sheet can be moved at the same time. Originally, the computer can do only one processing at the same time. However it can operate at the same time because each software has been switched according to very short timing. That is a function that OS rules, it can be said that OS manages "Resource" such as hardware.
1.1.2. Convenient and inconvenient points in OS Because OS offers various functions, and absorbs the difference of hardware, it is very convenient. However, because OS consumes "Resource" of hardware, it is not necessarily effective all. For instance, a vending machine in the town, because the function is limited, the function that corresponds to OS is not provided. Because danger that OS causes the trouble is not avoided, it is made it to a simple design as much as possible. Moreover, the cellular phone did not have OS before. However, a recent cellular phone became very multifunctional such as mail, the access to portable sites, the executions of a mobile application program, etc. besides the telephone call. As a result, it is judged that the introduction of OS is appropriate, and has been almost introduced OS as for a recent cellular phone.
1.2. UNIX 1.2.1. Birth of UNIX UNIX was born in Bell Laboratory of AT&T. At that time, OS named MULTICS was being developed as an advanced research by Bell Laboratory. Mr. Ken Thompson who was the researcher discovered the computer not used in sideward of the laboratory, and installed small OS in the computer to test the mechanism that he thought independently, It is said that it is a birth of UNIX.
Because MULTICS had aimed at the multifunction and high performance too much, the research and development were frustrated. Mr. Ken Thompson introduced functions of MULTICS to the small OS, then the prototype of UNIX was completed. Actually, UNIX worked very compactly the small turn, and came to be used also for a variety of experiment projects. There is details used as OS to move the document composition software when the software of the document proofreading is needed in AT&T. Moreover, because AT&T had not thought about UNIX as a commodity at that time, use had been freely permitted only by paying the expenditures of the carriage and the media fee, etc. Moreover, the user who obtains it was able to research, to develop, and to change originally because it distributed a basic part concerning the design of UNIX called a source code as it was.
1.2.2. Various separation and integration As for distributed UNIX, remodeling has come to be given to each freedom. Then, UNIX of subspecies is made, and it has become shapeless. Then, AT&T came to manage UNIX including the licensing agreement formally. At the following, only the organization that made AT&T (And, group of the management of the license of UNIX) and the contract came to be able to declare UNIX OS that its company had put out. Of course there is an organization that doesn't place a contract.Even if the form of UNIX is taken, UNIX OS that those organizations put out is not formal UNIX. They are called "UNIX system OS" or "UNIX compatible OS". Therefore, even if it is said to a word UNIX, there are correct UNIX in the law that it enters into licensing agreements formally and compatible OS that takes the same form as UNIX exists.
1.2.3. Derivation UNIX Quite a lot of UNIX including compatible OS has spread like that. It is Berkeley version UNIX to have exerted a big influence in derivation UNIXs. Berkeley version UNIX is derivation OS made when Mr. Ken Thompson who is the developer of UNIX is in University of California Berkeley school. There is a part where the design was greatly changed. Moreover, IP (Internet protocol) that had been adopted as a communication method in the U.S.Army at that time was implemented by the function update. UNIX was strong in the Internet, because this details existed. It came to call UNIX of AT&T as System V system UNIX and BSD system UNIX as BSD UNIX, and it divided from now on for a long time.
1.2.4. Birth of Linux A lot of UNIX had been used in the enterprise and the university etc. under a high license fee. It is a dream among many users that it can be used with the personal computer at home. The person who developed UNIX that operated with the personal computer showed up actually. The article "I was making UNIX-compatible OS now" flowed on the Internet in 1991. The contributor is a university student in Finland named Linus Torvalds, and it seems to have begun to write such a program from the study of the function of the computer.The program was open to the public on the network. The prototype of the program was very primitive, and it was able to move only between computer literates. Though the basis of the design was just like UNIX, it is a original UNIX compatible OS without
the flow of System V and BSD. Necessary tools etc. were combined after that, and it came to operate splendidly as UNIX-compatible OS. This is a birth of Linux. The feature in the program of Linux was the license form. The license form named GPL (GNU General Public License) was adopted in the program of Linux. In the license form of software, that the project of GNU proposed, the feature in GPL is to be included the following content. Freedom of use and re-distribution Freedom of modification Guarantee of disclosing the modified content (You may modify it, but you must disclose the modified content), therefore various users was able to get and use it without charge freely. In addition, because the modification was permitted, it is possible to improve it. However, on the license, there was a condition that you must disclose the content (If it was demanded). As a result, the style that some individuals and organization don't conceal improvement result and all user received the favor and developed was completed.
1.3. Characteristic of UNIX system OS 1.3.1. Kernel and User land It was explained that software divid to basic software and applied software. They are called as "Kernel" and "User land". There are the following characteristic in each. Kernel It manages hardware. Any program can not operate hardware directly without the kernel. Hardware is managed. Any program cannot operate hardware directly without the kernel. Each computer have various differences on hardware. However, the kernel does not communicate the difference to the program which runs on the user land and the user who uses the program. The function of OS "Resource management" indicates this kernel. User land Applied software run. Under the environment offered by the kernel, programs are run. Because the kernel manages hardware, it can not operate hardware directly. Mr. Linus who developed Linux declared first "The kernel is being developed." And he opened the kernel to the public, people all over the world offers the program of the user land, and today's Linux exists. There are plural in the meaning that word Linux contains. As one of them, Linux points strictly at the kernel. This is a meaning of the narrow sense of word Linux.
1.3.2. Using UNIX UNIX system OS is basically operated by the command. The command operates in the user land. The GUI environment named X Window System (following description) exists and the operation based on the mouse input (click etc.) is possible too.
1.3.3. Shell It explained that UNIX system OS was operated by the command in the preceding clause. The command is literal "Instruction", and includes the command of various usages. The interactive command input environment is prepared in UNIX, and it is called the shell. The shell understands the input command, and executes it. Two functions are greatly provided in the shell. One is to accept the command input as shown in the above-mentioned. Another one is the execution of the shell script. The shell script is explained in the following chapter, but if it explains easily here, "The hand input command can be executed automatically." It is a function of the shell to offer the environment of the automatic execution.
1.3.4. Login In UNIX system OS, when beginning to use it, the login name and the password are input. This is said, "Login". The purpose of login is to obtain the permission to use the computer. The password is used to secure the login name and the password corresponds to the password number of the account when the login name is assumed to be an account number of the bank. The combination of the login name and the password is called an account, and the permission to use the computer where the account doesn't exist is not obtained.
1.4. Distribution 1.4.1. Birth of distribution Linux pointed at the kernel as shown in the above-mentioned. Moreover, using the tool that GNU offered, various programs such as the command are offered, then it has come to function as UNIX. However, only the user with a high skill was able to use Linux because operation until operating, that is
the installation, is very difficult. Therefore, collecting necessary programs, making an easy installer, even the user with a not high skill was made to be able to install it easily. It is calld the distribution. In the organization that is offering the distribution, there are various policies. There is an organization that confirms the operation thoroughly and tries to offer little trouble and steady program even if somewhat old. And there is an organization too that tries to offer as latest a program as possible. And there is an organization too that changes a part of existing distribution, adding an original package, and says as an original distribution. One example of distributions: Red Hat Enterprize LinuxDebian GNU/Linux
1.4.2. Package In talking about the distribution, the package is a necessary mechanism. When it begins to use Linux as shown in the above-mentioned, it is necessary to install various programs. There are the following problems besides the installation method is difficult without the package. The complex program needs plural dependent programs.If the dependent program depends for another program in addition, it should be installed in correct place and with correct order. An active program to develop always has the update. When a new program is installed, after an old program that is operating now is beautifully deleted, then it should be installed. The delete operation besides the install operation is very difficult. The package is used to solve these difficult problems. The package manages the installed file and the version of the program. Moreover, when the package is installed, the dependent package is also installed automatically because the dependency of the program is managed. There is an enterprise named RedHat as a distribution to contribute to the management of the package greatly. RedHat developed the mechanism named RPM(RedHat Packaging Manager) for its own distribution. It is general to use this PRM for the package management now. In a part of distributions, the package management of the DEB form might be used. It will be able to be said that RPM is 90% or more if it says in the ratio. The state that is installed including the distribution with the package and is working might be called Linux. This is a meaning of the wide sense of Linux.
1.5. The chapter test 1. Let's give three kinds of applied software of the personal computer that usually uses it. 2. Let's give two hierarchies that exist in UNIX system OS. 3. Let's list three advantages of introducing the package.
