main content
1, process
2, the structure of the operating system
3, the operating system's development history
4, Kernel version of the problem with the GNU / Linux system
5, open source system
6, Centos installation and a small portion of the used
7, Linux installation and brief order
1, process
There are two main concepts of the process: first, the process is an entity. Each process has its own address space, under normal circumstances, including the text area (text region), the data region (data region) and stack (stack region). Code is executed by a processor stored text area; dynamically allocated memory area stores data used during execution process variables; stack area stores instructions and local variables of the calling procedure activities. Second, the process is an "execution procedures." Program is a lifeless entity (operating system performs the) only when the processor attached to the program of life, it can become an active entity, we call for the process.
Operating system process is basic and important concepts. The default is the daemon program process --- a normal process, the program will start its own program process, the general process relies on daemons.
( Note: Not all process can directly call the system call to use direct hardware resources, most of the normal process can not go directly to the hardware resources by calling syste call, they need the help of library files, to run properly on your system. )
Library files on Windows suffix is .dll, library files on Linux suffix is .os
Shell is the most common way to interact with the Linux operating system, bash is the most basic interaction (ps command to see the process under Linux --process)
Graphical interactive programs on Linux systems is also a common application, common graphics program ---- KDE, GNOME, Xface .......
2, the structure of the operating system
Hardware --kernel ----------- application
(system call)
------------ library ---- ordinary process (special: interactive shell (managers and systems))
3, the operating system's development history
Early development of the operating system intention is to achieve a batch function, and early batch system can not play the full functionality of the hardware, so the company began developing the three systems multi-tasking multi-process, the three companies GE General Electric, BELL Bell Labs , MIT Massachusetts Institute of Technology, in 1970, when the birth of the first operating system multics system (multi-tasking operating system);
after the completion of system development, they lost the original target, and so GE BELL pulled out of the project, which BELL a young scientist Ken Thomson (ken thompson), apply to the company in order to run his own space travel game purchase of a computer system, which was rejected the company; therefore, he based PDP DEC (digital equipment) developed 7 (best time is PDP-11) system developed its own system, used to run space travel, that's behind us Unix systems (DEC company also has a system (VMX))
ken except invented Unix systems , he was the inventor of the C language; 1973 C language was invented, ken and his colleagues can not wait Ritchie C language Rewrite the Unix system;
because of the huge contribution to the computer industry, ken get a year of paid annual leave, at this time there, he went to the University of California, Berkeley; and in this school, which has a distinguished student Bill Joy (SUN founder), he organized BSRG, and BSRG developed a new system BSD (Unix and similar) under the leadership of ken. At this point BSD commercialization, began selling to make money; but the owner of the Unix system BELL laboratories have begun to sell after the company was acquired by Novell, and for reasons similar to the code, because of copyright issues between the two, hit a decade of lawsuits and in this decade the inside, the new iT giant quietly developed, it is Mircosoft;
1981年个人PC机的兴起为微软带了商机，他借助母亲的关系，将转轴买来的的CP/M系统敲敲打打后，也就是我们后来为人所知的DOS系统，转手卖给了IBM；此时PC机市场有着一个巨无霸，那就是jobs的苹果公司；苹果Apple1系统基于Unix开发，要远远强于DOS系统，同时jobs在Xerox公司的PARC实验室那看到了鼠标与图形界面的开发，它从Xerox公司购买到了图形界面，而比尔盖茨则假装帮助jobs开发图形界面。而得到图形界面的比尔盖茨将自己的DOS从新开发，这就是Windows系统；
Windows系统可以说在系统行业属于非常差的系统，经常蓝屏，比尔盖茨为了解决这个问题，推导了原本CP/M的框架从新使用了DEC的vmx系统作为底层开了一个新的系统，这就时候我们的Windows NT；
十年后，当Microsoft非常强大以后，BSD和Unix停止了官司，开始发展自己的系统，其中BSD开发了FreeBSD OpenBSD NetBSD；与此同时，Bill Joy则在这时候成立了自己的小型机系统SUN OS，也就是我们后面所知道的Solaris；SUN 2001年被oracle收购；*SUN为我们的Linux引入了CSHELL；而基于Unix系统则各个厂家开发了自己的系统例如上面说到的solaris，以及IBM的AIX和惠普的HP-Unix；
此时的系统市场已经高度商业化；Unix、BSD商业化以后，大学里面就无法在使用这些系统教学了，此时，荷兰大学的一个教授Andrew开发了自己系统Minix系统。此时有个学生linus想使用Minix系统，但是想修改minix里面的一些驱动程序，所以自己开发了一个Linux系统；此时和80年代的一个stallman发起了freedom计划，也就是GNU计划，GNU is not unix；GPL宣言也由此诞生，General Public License；Emacs/gcc(GNU C Complier)也就是GNU计划提供的软件；
我们说此时的GNU/Linux系统只是C语言的源代码程序，而想要运行起来就必须对这些C语言程序进行编译；而为了兼容各种CPU硬件架构，这是就出现了一些第三方公司，来开发Linux的打包程序的公司：其中包括RedHat SLS Debian SUSE，他们只是将Linux的源代码进行编译，能够让Linux系统在各种硬件上面运行，这些厂家就叫做Linux的发行商。
4、内核与GNU/Linux系统的版本问题
内核版本---kernel
GNU/Linux版本---发行商版本
常见：红帽（RedHat）(收取服务费)---Centos,Fedore,openSUSE(欧洲) ； Debian(安全)---Ubuntu，（麒麟、红旗）
5、开源体系
a.GNU
全称：GNU is Not Unix
GNU计划：将商业版的软件程序进行开源的一个计划
GPL协定：如果你使用了GNU计划中定义的开源软件代码，这样的话，你就必须将对应的所有代码进行开源。
b.BSD
c.Apache(阿帕奇)
本身是一个做网站起家的社区，Hadoop项目在2005年秋天作为Lucene的子项目Nutch的一部分正式引入，称为Apache项目的顶级项目。
6、Centos的安装与一小部分使用
在安装过程中，自定义硬件处选择新（CD),再选择使用ISO映像文件（将CentOS-6.6-i386-minimal.iso文件选入），然后继续；不需要做磁盘检测，所以选择skip。
注：CTRL + alt 释放鼠标，不再锁定-----tab是转换----CTRL + alt + enter是虚拟机界面全屏
7、Linux的安装与命令简介
1、安装
a.直接将操作系统安装在硬件设备上（双系统）————比较麻烦，不给予推荐
b.使用VMM管理平台来进行安装（虚拟机的方式）————VMM管理平台：VMware workstations , Virtualbox
硬盘的划分：3个区域必须要划分：/boot（启动时指定文件），swap（交换分区），/（根分区）
拍摄快照：如果出错，可以恢复快照（虚拟机--快照--拍摄快照--初始化状态）
2、常用Linux命令的基本使用
- ls：list查看当前文件夹下的内容（当前根目录）
- pwd：显示当前路径（绝对路径）
- cd（目录名）：切换到目标目录
- touch（文件名）：修改时间戳
---扩展：stat命令用于以文字的格式来显示inode内容
atime访问时间，ctime修改文件属性的时间，mtime修改文件内容的时间
- mkdir（目录名）：创建文件夹，目录
- rm（文件名）：remove 删除
- clear：清屏 = CTRL + l