期末_操作系统实验课程设计.doc

操作系统实验课程设计（二）（参照实验五）学院：计算机科学与工程 专业： 信息管理工作与信息系统 学号： 2008142118 姓名： 丁建东 一、 实验题目：设计一个Shell解释器二、 实验目的：本设计的主要目的在于学会如何在Unix系统下创建进程和管理进程。三、实验内容：实现一个简单的shell（命令行解释器），类似于bash, csh等。要求实现的shell支持以下内部命令：1. cd 更改当前的工作目录到另一个。如果未指定，输出当前工作目录。如果不存在，要求有适当的错误信息提示。改命令应能够改变PWD的环境变量。2. echo 显示echo后的内容且换行。3. help 简短概要地输出你的shell的使用方法和基本功能。4. jobs输出shell当前的一系列子进程，要求提供子进程的命名和PID号。5. quit, exit, bye退出shell。所有的内部命令应当优于在$PATH中同名的程序。任何非内部命令必须请求shell创建一个新进程，且该子进程执行指定的程序。这个新进程必须继承shell的环境变量和指定的命令行参数。要求实现的shell支持以下内部命令：Batch Processing 如果shell启动带有一个文件名作为参数，打开该文件并执行文件里所有命令。待所有进程全部结束退出shell。四、实验思路： 1.所用到的系统函数（1）打开目录void cd()API调用：int chdir(dir)；getcwd(dir,dir_max)；实现：改变当前目录，并判断目录是否存在。（2）回应void echo()实现：用户输入字符串，以回车结束输入。char echo_stringecho_lenecho_max;/用户输入命令，以空格符隔开，存为字符串数组按顺序输出用户输入的字符串。（3）输出当前子进程Void jobs()API调用：shmget（），shmat（）实现：开辟一个共享内存区，一旦创建一个子进程，就把该进程的进程ID和名字记字共享区里，在子进程结束的时候消除该记录。这样，调用jobs时只要读取共享区里的记录并输出就可以知道当前运行的子进程了。（4）输出当前路径void pwd()API调用：getcwd（）；五、程序流程图。六、程序代码#include #include #include #include #include #include #include #include #define MAXLENGTH 25#define SUBLENGTH 5#define LINELENGTH 40#define ECHO myshell#define QUIT exitchar * readline;typedef enum EXEC,REDI,REDIS,PIPE,NOHUP,BACKGROUNDTokenType;typedef void (*fun)(char *);void analyse(void);void exec(char*);void redi(char*);void piped(char*);void bgtask(char*);sigset_t *set;int main(void) readline = (char *) malloc(MAXLENGTH*sizeof(char); set = (sigset_t *)malloc(sizeof(sigset_t); sigemptyset(set); if( sigaddset(set,SIGINT) = -1) printf(sigset error1!n); exit(0); if(sigprocmask(SIG_BLOCK,set,NULL) = -1) printf(sigset error2!n); exit(0); while(1) /signal(SIGINT,SIG_IGN); /ctrl+c is ignored fputs(ECHO,stdout);/printf echo gets(readline);/gets readline if(strncmp(readline,QUIT,4) = 0) /equal exit then exit free(readline); return 0; analyse();/analyse /analyse the readlinevoid analyse(void) TokenType type = EXEC; /command style int i = 0; char c ； /function mapping fun fun_array = exec, redi, NULL, piped, NULL, bgtask ; /the nohup is amazing /* /test if contains nohup if(!strncmp(readline,nohup ,6) printf(nohup!n); signal(SIGHUP,SIG_IGN);/ SIGHUP is ignored int j = 6; c = *(readline+j); /deal with the readline while(c != 0) *(readline+i) = c; i+; j+; c = *(readline+j); *(readline+i) = 0; i = 0; */ c = *(readline+i); /control the TokenType while(c != 0) if(c = ) type = REDI; *(readline+i) = +; else if(c = ) type = REDIS; *(readline+i) = +; else if(c = |) type = PIPE; *(readline+i) = +; else if(c = &) type = BACKGROUND; *(readline+i) = +; i+; c = *(readline+i); /with the function array ,do it (*fun_arraytype)(readline);/execute simple commandvoid exec(char * p) printf(%sn,p); char * tmp = (char *)malloc(SUBLENGTH*sizeof(char*); int num = 0; pid_t pid; /split the string tmpnum = strtok(p, ); while(tmp+num = strtok(NULL, ) ; pid = fork(); if(pid = 0) if(sigprocmask(SIG_UNBLOCK,set,NULL) = -1) printf(sigset error!n); exit(0); /execute it int error = execvp(tmp0,tmp); if(error void redi(char *p) char * str = strtok(p,+); char * file_name = strtok(NULL, ); char *tmp = (char *)malloc(SUBLENGTH*sizeof(char*); int num = 0; int file,file_old,file_new; pid_t pid; tmpnum = strtok(str, ); while(tmp+num = strtok(NULL, ) ; / open the file file = open(file_name,O_WRONLY | O_CREAT); if(file = -1) printf(open file error!n); free(tmp); / inorder to recover file_old = dup(STDOUT_FILENO); / redirect the stream file_new = dup2(file,STDOUT_FILENO); if(file_new = -1) printf(dup error!n); close(file); return ; pid = fork(); if(pid = 0) int error = execvp(tmp0,tmp); if(error 0) printf(Command is not found!n); exit(0); close(file); free(tmp); exit(0); else wait(NULL); /recover the stream if(dup2(file_old,file_new)= -1) printf(dup2 errorn); /command contains |void piped(char *p) char *str1 = strtok(p,+); char *str2 = strtok(NULL,+); char lineLINELENGTH; / use pipe implements the | FILE *in = popen(str1,r); FILE *out = popen(str2,w); if(in = NULL|out = NULL) printf(popen error!n); return ; /read the string and write to out while(fgets(line,LINELENGTH,in) != NULL) if(fputs(line,out) = EOF) printf(fputs error!n); pclose(in); pclose(out); / implements background task void bgtask(char *p) char *str = strtok(p,+); char *tmp = (char *)malloc(SUBLENGTH*sizeof(char *); int num = 0; pid_t pid; /split tmpnum = strtok(st