操作系统实验报告 shell程序

1、操作系统实习报告 日期： 实习题目： shell程序完成人姓名：组号：学号实习内容简要描述本实验要实现一个简单的命令解释器，也就是Linux中的shell程序。实验程序起名为ysh，要求其设计类似于目前流行的shell解释程序，如bash、csh、tcsh，但不需要具备那么复杂的功能。ysh程序应当具有如下一些重要的特征：能够执行外部程序命令，命令可以带参数。 能够执行fg、bg、cd、history、exit等内部命令。 使用管道和输入输出重定向。支持前后台作业，提供作业控制功能，包括打印作业的清单，改变 当前运行作业的前台/后台状态，以及控制作业的挂起、中止和继续 运行。除此之外，在这个实

2、验中还须做到： 使用make工具建立工程。 使用调试器gdb来调试程序。 提供清晰、详细的设计文档和解决方案。主要代码结构（附注释）#include <stdio.h>#include <ctype.h>#include <string.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <sys/wait.h>#include <math.h>#includ

3、e <signal.h>#include <stdlib.h>#include "ysh.h"#define NO_PIPE -1#define FD_READ 0#define FD_WRITE 1int is_founded(char * cmd) int k = 0; while(envpathk != NULL) strcpy(buf,envpathk); strcat(buf,cmd); if(access(buf,F_OK) = 0) return 1; k+; return 0;void getenviron(int n,char *

4、s) int i = 0,j = 0,k = 0; char c; char buff80; char * p; while(c=si) != '=') buffi+ = c; buffi+ = '0' if(strcmp(buff,"PATH") = 0) while(si != '0') if(si = ':') buffj+ = '/' buffj = '0' p = (char *)malloc(strlen(buff) + 1); strcpy(p,buff); env

5、pathk+ = p; envpathk = NULL; j = 0; i+; else buffj = si; j+; i+; else fprintf(stderr,"No match");int getline(int fd,char * buf) int i = 0; char c; while(read(fd,& c,1) bufi+ = c; if(c = 'n') bufi-1 = '0' return i; return i;void init_environ() int fd,n; char buf80; if(fd

6、 = open("ysh_profile",O_RDONLY,660) = -1) printf("init environ variable error!n"); exit(1); while(n = getline(fd,buf) != 0) getenviron(n,buf); envhis.start = 0; envhis.end = 0; head = end = NULL;int pipel(char * input,int len) char * argv1030; char * filename0; int i,j,k,is_bg =

7、0; int li_cmd = 0; int fd101,pipe_in = -1; int pipe_out = -1,flag = 0; pid_t pid; for(i = 0,j = 0,k = 0;i <= len;i+) if(inputi = ' ') | (inputi = 't') | (inputi = '0') | (inputi = '|') | (inputi = '>') | (inputi = 'n') if(inputi = '|') |

8、(inputi = '>')if(inputi = '>') flag =1;if(j > 0 ) bufj+ = '0' argvli_cmdk = (char *)malloc(sizeof(char) * j); strcpy(argvli_cmdk,buf); k+;argvli_cmdk = (char *)0; li_cmd+; k = 0;j = 0; if(j = 0)continue; elsebufj+ = '0'if(flag = 0) argvli_cmdk = (char *)mallo

9、c(sizeof(char) * j); strcpy(argvli_cmdk,buf); k+; else filename0 = (char *)malloc(sizeof(char) * j); strcpy(filename0,buf); j = 0;else if(inputi = '&') && (inputi = '0') is_bg = 1;continue; bufj+ = inputi; argvli_cmdk+ = NULL; for(i = 0;i <= 10;i+) fdiFD_READ = NO_PIPE

10、;fdiFD_WRITE = NO_PIPE; for(i = 0;i < li_cmd;i+) if(pipe(fdi) = -1) printf("Can not open pipe!n"); return 0; for(i = 0;i < li_cmd;i+) if(is_founded(argvi0) = 0) printf("Can not found command!n"); break; if(i != 0) pipe_in = fdi - 1FD_READ; else pipe_in = NO_PIPE; if(i != li

11、_cmd) pipe_out = fdiFD_WRITE; else if(flag = 1) if(pipe_out = open(filename0,O_WRONLY | O_CREAT | O_TRUNC,S_IRUSR | S_IWUSR) = -1) printf("Can not open %sn",filename0);return 0; else pipe_out = NO_PIPE; if(pid = fork() < 0) printf("Fork failed!n"); return 0; if(pid = 0) if(pip

12、e_in = NO_PIPE) close(pipe_in);if(pipe_out = NO_PIPE) close(pipe_out);if(pipe_out != NO_PIPE) dup2(pipe_out,1); close(pipe_out); if(pipe_in != NO_PIPE) dup2(pipe_in,0); close(pipe_in);execv(buf,argvi); else if(is_bg = 0) waitpid(pid,NULL,0);close(pipe_in);close(pipe_out); return 0;void add_history(c

13、har * inputcmd) envhis.end = (envhis.end + 1) % HISNUM; if(envhis.end = envhis.start) envhis.start = (envhis.start + 1) % HISNUM; strcpy(envhis.his_cmdenvhis.end,inputcmd);void history_cmd() int i,j = 0; if(envhis.start = envhis.end) return; else if(envhis.start < envhis.end) for(i = envhis.start

14、 + 1;i <= envhis.end;i+) printf("%dt%sn",j,envhis.his_cmdi); j+; else for(i = envhis.start + 1;i < HISNUM;i+) printf("%dt%sn",j,envhis.his_cmdi); j+; for(i = 0;i <= envhis.end;i+) printf("%dt%sn",j,envhis.his_cmdi); j+; void cd_cmd(char * route) if(route != NUL

15、L) if(chdir(route) < 0) printf("cd;%s Error file or directory!n",route); void jobs_cmd() struct NODE * p; int i = 1; p = head; if(head != NULL) do printf("%d %d %st%sn",i,p -> pid,p -> state,p -> cmd); i+; p = p -> link;while(p != NULL); else printf("No jobs!n

16、");void add_node(char * input_cmd,int node_pid) struct NODE * p; p = (struct NODE *)malloc(sizeof(struct NODE); p -> pid = node_pid; strcpy(p -> state,input_cmd); strcpy(p -> state,"running"); p -> link = NULL; if(head = NULL) head = p; end = p; else end -> link = p; en

17、d = p; void del_node(int sig,siginfo_t * sip) struct NODE * q; struct NODE * p; int id; if(sig_z = 1) sig_z = 0;goto out; id = sip -> si_pid; p = q = head; if(head = NULL) goto out; while(p -> pid != id && p -> link != NULL) p = p -> link; if(p -> pid != id) goto out; if(p = h

18、ead) head = head -> link; else while(q -> link != p) q = q -> link;if(p = end) end = q; q -> link = NULL;else q -> link = p -> link; free(p); out:return;void setflag() sig_flag = 1;void ctrl_z() struct NODE * p; int i = 1; if(pid1 = 0) goto out; if(head != NULL) p = head; while(p -

19、> pid != pid1) && (p -> link != NULL) p = p -> link;if(p -> pid = pid1) strcpy(p -> state,"stopped");else add_node(input,pid1); strcpy(end -> state,"stopped"); else add_node(input,pid1); strcpy(end -> state,"stopped"); sig_z = 1; kill(pid1,S

20、IGSTOP); for(p = head;p -> pid != pid1;p = p -> link) i+; printf("%dt%st%sn",i,end -> state,end -> cmd); pid1 = 0;out:return;void bg_cmd(int job_num) struct NODE * p; int i = 0; p = head; for(i = 1;i < job_num;i+) p = p -> link; kill(p -> pid,SIGCONT); strcpy(p -> s

21、tate,"running");void fg_cmd(int job_num) struct NODE * p; int i = 0; p = head; for(i = 1;i < job_num;i+) p = p -> link; strcpy(p -> state,"running"); strcpy(input,p -> cmd); pid1 = p -> pid; signal(SIGTSTP,ctrl_z); kill(p -> pid,SIGCONT); waitpid(p -> pid,NUL

22、L,0);int main() init_environ(); while(1) char c; char * arg20; int i = 0,j = 0,k = 0; int is_pr = 0,is_bg = 0; int input_len = 0,path; int pid = 0,status = 0; struct sigaction action;action.sa_sigaction = del_node;sigfillset(& action.sa_mask);action.sa_flags = SA_SIGINFO;sigaction(SIGCHLD,&

23、action,NULL);signal(SIGTSTP,ctrl_z); path = get_current_dir_name();printf("ysh%s ",path);while(c = getchar() = ' ') | (c = 't') | (c = EOF) ;if(c = 'n') continue;while(c != 'n') bufinput_len+ = c; c = getchar();bufinput_len = '0' input = (char *)mall

24、oc(sizeof(char) * (input_len + 1);strcpy(input,buf); for(i = 0,j = 0,k = 0;i <= input_len;i+) if(inputi = '<') | (inputi = '>') | (inputi = '|') if(inputi = '|') pipel(input,input_len); add_history(input); free(input);else redirect(input,input_len); add_histo

25、ry(input); free(input);is_pr = 1;break; if(is_pr = 1) continue;for(i = 0,j = 0,k = 0;i <= input_len;i+) if(inputi = ' ') | (inputi = '0') if(j = 0) continue; else bufj+ = '0' argk = (char *)malloc(sizeof(char) * j); strcpy(argk+,buf); j = 0; else if(inputi = '&'

26、;) && (inputi + 1 = '0') is_bg = 1; continue; bufj+ = inputi; if(strcmp(arg0,"exit") = 0) add_history(input); printf("Bye bye!n"); free(input); break; if(strcmp(arg0,"history") = 0) add_history(input); history_cmd(); free(input); continue;if(strcmp(arg0,

27、"cd") = 0) add_history(input); for(i = 3,j = 0;i <= input_len;i+) bufj+ = inputi; bufj = '0' arg1 = (char *)malloc(sizeof(char) * j); strcpy(arg1,buf); cd_cmd(arg1); free(input); continue;if(strcmp(arg0,"jobs") = 0) add_history(input); jobs_cmd(); free(input); continue

28、;if(strcmp(arg0,"bg") = 0) add_history(input); for(i = 0;i <= input_len;i+) if(inputi = '%') break; i+; for(;i <= input_len;i+) bufj+ = inputi; bufj = '0' arg1 = (char *)malloc(sizeof(char) * j); strcpy(arg1,buf); bg_cmd(atoi(arg1); free(input); continue;if(strcmp(arg0,"fg") = 0)