linux环境下命令行解释器sh小例

1、the child. VIII health supervision and law enforcement. Accelerating the construction of health inspection system, comprehensive implementation of food safety coordination responsibilities, strengthening health law enforcement and supervision, increase the intensity of combat of illegal practice. IX

2、 carrying patriotic public health campaign. Further develop urban and rural sanitation and clean, and promoting health education and health promotion work, create smoke-free health units carry out activities, full implementation of the rural drinking water and latrines project. X efforts to raise th

3、e level of medical services. Active implementation of XX County Hospital construction projects, strengthen the county peoples hospital medical building, upgrading of township hospital medicine services, and constantly improve the level of service, and better meet the needs of the people. Integrated

4、and other health programs. Continued solid job maintaining stability, carry out the Hui ju work to promote clean government and anti-corruption work JIU feng, and do a new round of health Xinjiang work, increased health letters, comprehensive management, safety, environmental protection, fire protec

5、tion, legal work, and efforts to promote the healthy and harmonious development of health service. District Judicial Council 2015 summary material 2015, XX District Judicial Council in district, and District Government of right led Xia, in superior business sector of carefully guide Xia, in here mem

6、bers line wind supervisor of care guide Xia, to party of 18 big and 18 session three in the, and four in the plenary spirit for guidelines, in-depth implement implementation science development views, according to province, and city, and district University workers workshop and early full District j

7、udicial administrative workshop of deployment, to service full district economic social development for Center, to created People are satisfied with a service-oriented administration of justice bodies to lead to further improve work style, improve administrative efficiency, and for the whole area of

8、 the rule of law area, accelerate the construction of rule XX provide a powerful legal guarantee and realize the new leap of XX the judicial administrative work. Our main approach is: first, innovation, and comprehensively promote the rule of law publicity and education work. Around the main line of

9、 spirit of carrying forward the Socialist concept of the rule of law, fully six . Dynamic, extensive Franco-Prussian district activities. Out of 45 per cent this year, sending pictures, literature, more than 40,000 copies. Young Franco-Prussian, set off a climax. Through the learning child star and

10、VCD youth double hundred selection, method in the heart, on the line essay, lucky star of English law and other activities, set off a new round of young people across the district law, usage, abide by the climax. Second, strengthen management and strive to build a new pattern of mediation. Full medi

11、ation video command system, the role of mediation Network Academy, promoting mediation network entities and the achievement of practical results. Enhanced grid troubleshooting warning mechanism, continue to promote medical, public, and prosecutors, against regulation, consumer culture, such as docki

12、ng, professional mediation organizations of normalized and standardized construction, urban management, logistics, land, and more new professional in the field of mediation and docking mechanism. Establishment of NPC deputies and CPPCC members, 西 安 邮 电 大 学进程和程序：编写命令解释器sh课程名称： 高级操作系统实验 专 业： 软件工程 学生学号

13、： 1303210047 学生姓名： 李力 community organizations and other mechanism for third parties to participate in mediation to resolve the contradiction, forming the participation of the whole society, the whole area covers of the mediation network and make concerted efforts and mutual accountability of the med

14、iation system. Troubleshooting warning to deepen the grid mode. Mesh and staffing continues to sound, troubleshooting warning system of grid coverage. Town linked to the patch-level mediation Center personnel mastering responsibilities grid cell and town-level individual grid cells and responsibilit

15、ies grid grid information contact the long point basis, assisting the production life of the masses in the encountered problems and disputes, found signs of hidden trouble to report first to the upper grid. In accordance with the screening requirements of grid, efforts to increase frequency and conc

16、entration of contradictions and disputes, disputes the Troubleshoot, mediate special events, truly things not out of the village, and not out of town, the contradiction is not submitted. Sound classification of disputes and separations for early warning, disposal systems and major disputes Express,

17、reporting and zero-reporting system, and constantly enhance the contradiction and dispute investigation and mediation work of the foresight, initiative and science. Improve the risk assessment of major disputes mechanism, do preventive work. 1-in June, the region has accepted mediation disputes 4299

18、, 4181 mediation success, three-level mediation organizations accepting mediation in 1673, 1648 mediation success, success rate of mediation 98.5%. 1115 discourage mass petitions, 138 meter-wide, preventing contradictions from intensifying 89, prevent the transfer penalty case 4/6 people. Mediation

19、Center mediation, 73, all mediation successful, involved compensation amount of 4.4165 million Yuan, of which 10 death dispute involving indemnity amount 2.456 million Yuan. Third, the solid foundation to enhance the special crowd control level of education. Promote the construction of judicial admi

20、nistrative. Staging batches to parts of town (Street) by Justice, and town (Street) led, judicial staff to negotiate the construction of judicial administrative difficulties in the work, and conducted door-to-door guidance. In accordance with provincial requirements, study guide the town (Park Stree

21、t) public legal services centre, the establishment of the judicial administrative stations in the village. The provincial Justice Department investigation about the construction of judicial administrative. On March 14, the provincial Office of the Department of Justice led to the second . Correction

22、 of the construction of information platform. Based on actual demand-oriented community corrections, in accordance with the principle of simple work, to further improve the system, optimization, enhance the integration of information and operations, improve work efficiency, our district intranet pla

23、tform of community corrections community inmates information input rate of 100%, mobile positioning and monitoring to achieve daily sporadic checks. Strictly regulate the evaluation of community correction mechanism, improve the quality of assessments. Further standardize the assessment mechanism, o

24、f all objects must be surveyed by field visits, participants include close relatives of the accused, the village (neighborhood) Committee cadre, the victim, police stations, and make conversation transcripts. Surveys including the defendant usually, neighborhoods, the village (neighborhood) the opin

25、ion of the目 录一、进程与程序2二、进程的理解22.1 进程结构理解2三、 shell 运行程序的方式43.1 shell的主循环43.2 一个程序建立、运行另一个程序，以及退出程序53.2.1 一个程序运行另一个程序的方式： exec函数。53.2.2 一个程序创建另一个程序的方式： fork函数。63.2.3 父进程在执行子进程退出后，继续执行的方式： wait函数73.2.4 shell运行程序7四、 实例演练：实现psh2.c84.1 步骤分析：84.2 程序流图94.3 核心代码10一、进程与程序 可执行程序是一个机器指令及其数据的序列，一个进程则是程序运行时的内存空间和设

26、置。程序是静止的进程是动态的。进程包括程序和程序处理的对象（数据集）。进程能得到程序处理的结果。进程和程序并非一一对应的。一个程序运行在不同的数据集上就构成了不同的进程。通常把进程分为系统进程和用户进程两大类。把完成操作系统功能的进程就称为系统进程，而完成用户功能的进程则称为用户进程。二、进程的理解进程存在于用户空间，用户空间是存放运行的程序和它们的数据的一部分内存空间。就像管理磁盘的多个文件，内核管理内存中的多个进程，为它们分配存储空间，并记录内存分配情况。2.1 进程结构理解为深入了解进程内容，我们通过源码进行学习：进程数据结构，Linux的进程控制块为一个由结构task_struct所定

27、义的数据结构，这个结构就在上面的sched.h中。这个文件中有一行代码：struct task_struct long state; long counter; /任务运行时间片 long priority; long signal; /信号。每个比特代表一种信号。 struct sigaction sigaction32; long blocked; /* bitmap of masked signals 进程信号屏蔽码*/ /* various fields */ int exit_code; /退出码，父进程会取得 unsigned long start_code; /代码段地址 uns

28、igned long end_code; /代码长度（字节数） unsigned long end_data; /代码长度+数据长度（字节数） unsigned long brk; /总长度 unsigned long start_stack; /堆栈段地址 long pid,father,pgrp,session,leader; /进程、父进程、进程组、会话、会话首进程号 unsigned short uid,euid,suid; /用户id、有效用户id、保存的用户id unsigned short gid,egid,sgid; /组id、有效组id，保存的组id long alarm;/

29、闹钟定时 long utime,stime,cutime,cstime,start_time; /用户态（系统态）运行时间、子进程用户态（系统太） unsigned short used_math; /是否使用了协处理器 /* file system info */ int tty;/进程使用tty的子设备号，1标识没有使用 unsigned short umask; /文件创建屏蔽字 struct m_inode * pwd; /当前工作目录i节点结构 struct m_inode * root; /根节点i节点结构 struct m_inode * executable; /执行文件i节点

30、结构 unsigned long close_on_exec; /执行时关闭文件句柄位图标志 struct file * filpNR_OPEN; /进程使用的文件表结构 /* ldt for this task 0 - zero 1 - cs 2 - ds&ss */ struct desc_struct ldt3; /本任务的局部表描述符。0空，1代码段cs，2数据段和堆栈段ds&ss /* tss for this task */ struct tss_struct tss; /进程的任务状态段信息结构 ;其中：extern struct task_struct *taskNR_TASK

31、S;为记录指向各PCB的指针，指针数组定义于/kernel/sched.c中，原定义为：struct task_struct*taskNR_TASKS = &(init_task.task), ;2.2、进程组、会话组、控制终端进程组，会话组的概念出现是为了linux方便管理的，主要是为了作业控制的。最常见的就是在终端上发送一个中断信号（crtl+c），这个中断信号会发送到控制终端的前台进程组。简单说，进程组是一个或者多个进程的集合，而会话（session）是一个或者多个进程组的集合。Unix系统中的内存分为系统空间和用户空间，进程存在于用户空间。建立一个进程时，内核要找到存放程序指令和数据的

32、空闲内存页。内核还要建立数据结构来存放相应的内存分配情况和进程属性。3、 shell 运行程序的方式要写一个shell，我们必须明白：1、 如何建立一个程序2、 如何运行一个程序3、 等待exit()3.1 shell的主循环Shell的主循环体可以用以下伪代码表示：while( 输入结束 ) 获取命令；执行命令；等待命令结束；其时间流图用下图表示：3.2 一个程序建立、运行另一个程序，以及退出程序3.2.1 一个程序运行另一个程序的方式： exec函数。exec 系统调用从当前进程中把当前程序的机器指令全部清除，然后在空的进程中载入调用时指定的程序代码，最后运行这个程序exec()小例：ma

33、in()char *arglist3;arglist0=ls; arglist1=-l; arglist2=0;printf(* About to exec ls -l/n); execvp(ls,arglist); printf( * ls is done /n); 运行指令 ls -l/usr/bin 该程序将不会显示 第二条指令 “* ls is done”，因为当执行到execvp(“ls”,arglist)时，内核将新进程载入进当前指令，替代了当前代码，如同换脑。如右图所示：。exec调整进程的内存分配，使之适应新的程序对内存的要求，相同进程，不同的内容。3.2.2 一个程序创建另一个程序的方式： fork函数。当系统调用fork函数后，内核将完成以下四步：首先：分配新的内存块