shell命令解释器资料

#include <sys/wait.h>#include <unistd.h>#include <stdlib.h>#include <stdio.h>#include <signal.h>#include <string.h>#include <fcntl.h>char *stack[1000]={"/"} ;int num=1;extern char **environ;/*内装式shell命令的函数声明:*/int lsh_cd(char **args);int lsh_help(char **args);int lsh_exit(char **args);int lsh_pushd(char **args);int lsh_popd(char **args);int lsh_dirs(char **args);int lsh_redirect1(char **args);int lsh_redirect2(char **args);int lsh_redirect3(char **args);int lsh_redirect4(char **args);int lsh_export(char **args);int lsh_echo(char **args);/*装入的命令列表,紧随其后的是相应的功能。

*/char *builtin_str[] = {"cd","help","exit","pushd","popd","dirs","export","echo"};int (*builtin_func[]) (char **) = {&lsh_cd,&lsh_help,&lsh_exit,&lsh_pushd,&lsh_popd,&lsh_dirs,&lsh_export,&lsh_echo};int lsh_num_builtins() {return sizeof(builtin_str) / sizeof(char *);}/* 安装在内部的函数实现。

. *//**@brief Bultin command: change directory.@param args List of args. args[0] is "cd". args[1] is the directory.@return Always returns 1, to continue executing.@brief Bultin命令:改变目录。

@param args参数列表。

args[0]是“cd”。

args[1]是目录。

@return总是返回1,继续执行。

*/int lsh_cd(char **args){if (args[1] == NULL) {fprintf(stderr, "lsh: expected argument to \"cd\"\n");} else {if (chdir(args[1]) != 0) {perror("lsh");}}return 1;}/**@brief内置命令:打印的帮助。

@param args参数列表。

不检查。

@return总是返回1,继续执行。

*/int lsh_help(char **args){int i;printf("Type program names and arguments, and hit enter.\n"); printf("The following are built in:\n");for (i = 0; i < lsh_num_builtins(); i++) {printf(" %s\n", builtin_str[i]);}printf("Use the man command for information on other programs.\n"); return 1;}/**@brief内置命令:退出。

@param args参数列表。

不检查。

@return总是返回0,终止执行。

*/int lsh_exit(char **args){return 0;}//pushd函数：int lsh_pushd(char **args){if(chdir(args[1]) != 0){perror("lsh");}else{stack[num++]=get_current_dir_name();int i=num-1;while(i>=0){printf("%s ",stack[i]);i--;}printf("\n");}return 1;}//popd函数：int lsh_popd(char **args){if(num<2){printf("popd:directory stack empty!\n");return 1;}num--;chdir(stack[num]);int i=num-1;while(i>=0){printf("%s ",stack[i]);i--;}printf("\n");return 1;}//dirs函数：int lsh_dirs(char **args){if(args[1]==0){int i=num-1;char m=stack[i];stack[i]="/";while(i>=0 ){printf("%s ",stack[i]);i--;}printf("\n");stack[num-1]=i;return 1;}else{if(strcmp(args[1],"-c")==0){//memset(stack,0,sizeof(stack));num=1;}if((strcmp(args[1],"-p")==0)&&(strcmp(args[2],"-v")==0)){int j=num-1;while(j>=0){printf("%d %s \n",num-1-j,stack[j]);j--;}}}}int file1,file2;//重定向1：int lsh_redirect1(char **args){file1=open(args[2],O_CREAT | O_RDWR);file2=dup(1);dup2(file1,1);close(file1);lsh_launch(args);dup2(file2,1);//close(file2);return 1;}//重定向2：int lsh_redirect2(char **args){file1=open(args[2],O_CREAT | O_RDWR);file2=dup(2);dup2(file1,2);close(file1);lsh_launch(args);dup2(file2,2);close(file2);return 1;}//重定向3：int lsh_redirect3(char **args){file1=open(args[2],O_CREAT | O_RDWR | O_APPEND);file2=dup(1);dup2(file1,1);close(file1);lsh_launch(args);dup2(file2,1);close(file2);return 1;}//重定向4：int lsh_redirect4(char **args){file1=open(args[2],O_RDONLY|O_TRUNC);file2=dup(0);dup2(file1,0);close(file1);lsh_launch(args);dup2(file2,0);close(file2);return 1;}//export:int lsh_export(char **args){int i=0;int buf[100];int *name;int *value1;int *value2;int *value3;if(args[1]==NULL){while(environ[i]!=NULL){printf("%s\n",environ[i]);i++;}}else{strcpy(buf,args[1]);name= strtok(buf,"=");strtok(NULL,":");value1= getenv(name);value2= strtok(NULL,":");value3=strcat(value1,value2);setenv(name,value3,1);}return 1;}int lsh_echo(char **args){printf("%s:%s\n",args[1]+1,getenv(args[1]+1));return 1;}/**@brief启动程序,等待它终止。

@param args零终止的参数列表(包括程序)。

@return总是返回1,继续执行。

*/int lsh_launch(char **args){pid_t pid;int status;pid = fork();if (pid == 0) {// Child processif (execvp(args[0], args) == -1) {perror("lsh");}exit(EXIT_FAILURE);} else if (pid < 0) {// Error forkingperror("lsh");} else {// Parent processdo {waitpid(pid, &status, WUNTRACED);} while (!WIFEXITED(status) && !WIFSIGNALED(status)); }return 1;}/**@brief执行shell内置或启动程序。