About Linux Introduction

First, Linux preliminary introduction

• Advantages of Linux

1. Free, open-source
2. Multi-threading, multi-user support
3. Good security
4. Superior in memory and file management
5. System stability
6. Consume less resources

• Disadvantages of Linux

1. Relatively difficult to operate

2. Lack of professional software and game support

• Application of Linux

1. Network server

2. Mission-critical applications (financial database, large Enterprise network management environment)

3. High Performance computing tasks for academic institutions

4. Handheld Systems (PDAs, mobile phones, navigation systems)

5. Personal office Use

• The Linux mascot/logo

Penguin (English name: Tux), Origin: Because Torvalds in childhood was bitten by penguins, so very impressive

In Linux, you can make tux speak by command:

#sudo Apt-get Install Cowsay

• The path of development of Linux

2. The early computer architecture is also very difficult to use, in addition to the instruction cycle shipowner unpleasant, operating interface is also very disturbing! Because at that time the input device only card reader, output device only printer, users can not interact with the operating system (multi-channel batch processing system). Later, due to hardware and operating system improvements, you can use the keyboard for information input.
4. At the beginning of 1960 , MIT (MIT) developed a time- sharing operating system, CTSS, which allows multiple terminals to be connected to the host, using the host's resources for operations. However, advanced hosts provide up to 30 terminals (only input and output functions)
6. around 1965 , Bell (Bell Labs), MIT (MIT) and GE co-sponsored the Multics Project , which was designed to allow more than 300 terminals to be connected to a mainframe. The complete historical note can be consulted: http://www.multicians.org/
8. around 1969 , the project was behind schedule, funding was scarce and Bell Labs withdrew.
10. In 1969 , Ken Thompson (Multics project participant) 4 weeks wrote out a set of kernel programs, kernel tools, and a small file system in assembly language. It was dubbed UNICs, and the system was a prototype of UNIX.
12. In 1973 , Ken Thompson and Dennis Ritchie (father of the C language) collaborated to write UNICs in a high-level language (because of the specificity of assembly language and the fact that the computer machine architecture was different at the time, So every time to install to a different machine will have to rewrite the assembly language, then the ready-made high-level programming language has a B language. But the core performance compiled by the B language is not very good. Later Dennis Ritchie to rewrite the B language into C, and then rewrite and compile the core of the UNICs in C language, and finally released the official UNIX version!
14. after 1973 , Bell Labs (affiliated at T-T American Telecom) partnered with the University of California, Berkeley (Berkeley). Bill Joy from the University of Berkeley, by modifying the original UNIX code, ported to the right machine, and developed a lot of tool software and compiler programs.
16. In 1977 , the UNIX branch BSD(Berkeley software distribution) was born. Bill Joy was also the founder of Sun's later company. Sun is developing its own commercial UNIX version at the core of BSD.
18. After 1977 , the major commercial companies began the development of UNIX operating systems. For example, the Aix of the home system V,IBM and companies such as HP and Dec have their own hosts paired with their Unix operating systems. At that time, Unix had not been ported to the PC, because the CPU in the early 286-person computer architecture was not capable of multitasking, and Unix was emphasizing multitasking, so no one was interested in porting UNIX to a personal computer.
20. 1979, AT/T introduced the System v Seventh edition of Unix, the biggest feature of this version is the PC that can support the x86 architecture. The UNIX copyright was withdrawn due to the business problem.
22. In 1984 , as the core source code for System V seventh was not open, Professor Andrew Tanenbaum (Tan Ningbong) began rewriting the original UNIX code and wrote Minix , the core program of Unix like. , and transplanted to x86.
24. The Minix operating system of the x86 architecture was born in 1986 .
26. 1984 , Richard Mathew Stallman Storman started , which is intended to create a free, open UNIX operating system. But a person weak, so first wrote some can run under Unix applet, so the GNU program gradually open awareness. But the visibility was not enough, and then he wrote a software that everyone needed (any software needed to be compiled into binaries to be executed), so he began to write the C compiler program, which is now quite famous GNU C Compiler (GCC)! In addition, he has written more jutting C function libraries (GNU C library), as well as basic interfaces that can be used to operate the operating system bash shell!

    Several important software developed by GNU, such as:
    ? Emacs
    ? GNU C (GCC)
    ? GNU C Library (glibc)
    ? Bash Shell

    And in order to avoid the development of the open source free software is taken to make and Lee Software, two is Stallman also the GNU non-FSF developed software, all hang the GPL (general public License) Copyright Proclamation ~ This FSF core view souvenirs is "copyright system is to promote import society import step means, copyright itself is not natural power." "For the two FSF about the 趌 two GNU want to go deeper, please refer to Chaoyang University of Science and Technology, Professor Hongchogui website http://people.ofset.org/~ckhung/a/c_83.php, quit directly to the GNU:/http Www.gnu.org has a more in-depth overview!

    Gun* Why is it called GNU? In fact GNU is the GNU's not unix abbreviation

28. In 1988 , there was a growing demand for the two graphical user interface (graphical user Interface, GUI), and in 1984 the X Window System was first published by MIT and other third parties, and set up a non-profit XFREE86 this organization.
30. In 1991 , Linus Torvalds of the University of Helsinki in Finland posted a message on the BBS that he wrote a small core program with tools such as Bash, GCC, which can operate on Intel's 386 machine. So many people are interested! From now on, Linux is an extraordinary journey!

• background: At the time, the entire University of Helsinki had only one new Unix system, with only 16 weaving machines (terminal). At that time the computer only has the computing function, terminal is only responsible for providing input/output. Under this kind of sentiment attaining, it is very difficult to meet the requirements of the demand, so I want to engage in a UNIX computer to play. Later, he knew that there was a Unix-like system that was fully compatible with UNIX and could run on the Intel 386 machine, and that's the Minix system that we mentioned earlier that Professor Tan Ningbong wrote for educational needs! After buying the latest Intel 386 PC, he immediately installed the Minix operating system. In addition, Minix this operating system is attached to the original code, so Torvalds also learned from this source code a lot of core programming design concepts!   
• Start to dry: Torvalds I was playing the compilation of the early Cairns regional, compiled to consult Cairns regional on two hardware has a very close cuss system,. First, he wrote three small programs, a program will continue to output a, one will continue to output B, the last one will be two programs to switch. He had three programs executed simultaneously, and as a result, he saw that the screen was smooth and ababab ... He knew that he had succeeded!

• Referring to Minix's design philosophy and the Code of the book, he carefully studied the performance optimization of the 386-person computer, then used the GNU Free software to combine the core program code with 386, and finally wrote the core program he needed. And this little thing really can run up on the top of the 386 ~ can also read the Minix file system. Oh, that's great! Not enough, he hoped that this asmeamerican order can get a few changes to build acial, two, he will this core placed in the Web to provide everyone download, at the same time on the BBS posted a message:

• The news has attracted a lot of attention, and they also went to the site of the offer to download the core to install. Interestingly, because Torvalds placed the core of the FTP site Directory is: Linux, Still, we call this core Linux.
• At the same time, in order to make Linux compatible with the two Unix system, and the second is to start to put some of the software can be operating on UNIX to run on Linux. He found that there were a lot of software that did not work on the core of Linux. This time he has two methods, one is to modify the software, ridiculed the software can run on Linux, the other is to modify the Linux, ridiculed Linux Fu Yi software can operate yingying fan! By the two Linux would like to be compatible with two Unix, two is the choice of the first thing in the "Modify Linux"! In order to ridiculed all software can be executed on Linux, and the second is the reference standard POSIX yingying *.

POSIX yingying * POSIX is the abbreviation for the Portable Operating System interface (Portable Operating system Interface), which focuses on the interface between the canonical core and the application, which is a standard published by the American Institute of Electrical Non-electronic workers Asmeamerican (IEEE).

• Linux virtual Team generation, for this group of never met virtual team data transmission, second, Linux will be established core website: http://www.kernel.org!
• 1994 , finally completed the core version of Linux ! Version 1.0. This version also adds support for the X Window system.
• 1996 , completed the Linux 2.0 version

Popular Science Development: < computer history >

< Silicon Valley Computer History Museum >

Second, the basic knowledge of Linux 1. Core version number of Linux

• • 2.6.18-92.el5 major version. Minor version. Release book-Modified version
  • The main and minor versions are odd: in the developing version (development) such as 2.5.XX, this core version is mainly used in testing does not develop new features, so usually this version is only used by core developers Asmeamerican division.
  • The primary and secondary versions are even: stable versions (stable) such as 2.6.xx, which are added to these versions when core functionality matures, are used primarily in general home computers and Enterprise editions. The emphasis on the two provides a relatively stable Linux job environment platform for users.
  • Release is a new release of the core version that has been added to a certain Asmeamerican degree under the attaining of the main and minor architectures.
  • If you have modified part of the program code for a version of the core, then the new core version that has been modified can be added to the so-called modified version.

2. Linux core version and distribution version

• Linux is essentially the core of an operating system and the core tools it provides. He is the GNU GPL licensing model, so that anyone can get the original code cannot execute this core program and can be modified. In addition, because the Linux reference POSIX training Ji Van, two is compatible with two UNIX operating systems, along can also be called Cookbook Unix like one.
• Many commercial companies abstain from nonprofit groups, integrating Linux Kernel (including tools) with operational software, plus their own creative tool programs that allow users to install/manage Linux systems directly on CD-ROM/DVD or through the network. This "Kernel + softwares + tools can be fully installed" boom, which we call Linux distribution, is generally translated into a fully installable suite, or a Linux publisher suite.
• All Linux distributions use kernel are released by http://www.kernel.org, and these developers are based on the Linux standard Base (LSB) as well as the directory schema of the file system Hierarchy Standard (FHS) and other standards developed. The only difference may be the management tools developed by the developers themselves, and the different patterns of the suite management.

? fhs:http://www.pathname.com/fhs/
? lsb:http://www.linuxbase.org/

• Main Linux distributions publisher URL:

Red hat:http://www.redhat.com
? fedora:http://fedoraproject.org/
? Mandriva:http://www.mandriva.com
? Novell suse:http://www.novell.com/linux/
? debian:http://www.debian.org/
? slackware:http://www.slackware.com/
? gentoo:http://www.gentoo.org/
? ubuntu:http://www.ubuntu.com/
? centos:http://www.centos.org/

• Chinese Linux Extension Program: CLE This suite, http://cle.linux.org.tw/developed a lot of Chinese language kits and translated a lot of English files, so that we can now use the Chinese Linux
• The well-known open source Licensing page:

GNU general public LICENSE:HTTP://WWW.GNU.ORG/LICENSES/LICENSES.HTML#GPL

GPL Version 2 Chinese cultural provisions, http://linux.vbird.org/linux_basic/1010appendix_A.php

Berkeley software Distribution (BSD): Http://en.wikipedia.org/wiki/BSD_license

Apache License, Version 2.0:http://www.apache.org/licenses/license-2.0

Iii. preliminary knowledge of Linux 1. Tips

• Login username root, equivalent to administrator under Windows
• Into the graphical interface #startx (the graphical interface consumes memory, the general server does not go to install)
• Shutdown Command #shutdown-H now shuts down immediately
• Restart Command #shutdown-r-now Immediate restart or #reboot
• User logoff command #logout
• Switch Admin account #su –root (log in as little as root)
• VI Editor
• Switch Directory command #cd directory name (CD ~ Switch to home directory, CD: Switch to parent directory, CD/switch to root directory)
• Show file directory #ls-L (list)-A (hidden)
• Shows which path is currently under #pwd

2. Files directory under Linux

• Linux file systems are hierarchical tree-like structures

/

Root Home bin Sbin mnt etc var boot

Root: The file that holds the root user

Home: Files for ordinary users

Bin: Store Common commands

Sbin: Store commands that you want to be able to use with certain permissions

MNT: Default mount directory for CD-ROM and floppy drive

Boot: Store the boot file (boot system)

ETC: Store configuration-related files (environment variables, etc.)

var: Storing files that change frequently

USR: holds the default folder for installing software

3. User management under Linux

In the Linux machine, the file attributes can be divided into "readable, writable, executable" and other parameters to define the applicability of a file, in addition, these attributes can also be divided into three categories, respectively, "file owners, files belong to groups, other non-owners and groups." This is a fairly good system confidentiality for project planning or other program developers.

• Add user (under root) #useradd xiaoming

• Set password   #passwd xiaoming (add password to current user without user)

• Delete User #userdel xiaoming (user deleted, but file is still in)

• Remove user and file directories   #user-R xiaoming

• Add Group #groupadd group name

• Assign users to a group #useradd-G Group name User name

• Delete Group   #groupdel group name

• Change the user's group #usermod –g user name

• Change the initial directory of user login   #usermod –d directory name User name

• View all groups in Linux #cat/etc/group | More (ID number of the group)

• View all user information in Linux #cat/etc/passwd               Note: Between fields to: separate

User Password User ID Group ID comment user Home directory resolver bash

Test x 505 505 NULL/home/test/bin/bash

4. linux file permissions

• Guideline one, in Linux, each user must belong to a group and cannot exist independently
• Guideline two, a user can be in more than one group, whichever is the most privileged
• Guideline three, when a user creates a file, the group in which the file is located is the user's group
• Guideline four, except for the owner of the file and the user in the group, other users of the system are other groups of files

The file has three permissions, R readable 4 means, W writable 2 means, x executable file 1 indicates

-rw-r--r--In addition to the first-outside, the remaining three are a group of

First-Indicates the file type (-for normal files, D for directories, and L for linked files)

First set of rw-: The file owner's permissions to the file 7=4+2+1

Second set of r--: The file is in the same party as the permissions 4=4+0+0

Third group r--: the permissions of the other group's users on the file 4=4+0+0

#ls-ahl View all groups of files

#chagrp Modify the group in which the file is located

To change permissions for all files in the entire directory, use the command #chmod –R 744 directory Name

Note: There are two directories in the documents directory, respectively, 123 and 456, 456 directories of the Files AA and BB under the root user only read and write (rw-) permissions, this we will be the 456 directory of all the files are changed to readable writable executable (RWX)

Iv. common commands for getting started with Linux

References: Bird's-cousin private cuisine

About Linux Introduction