??本次實驗課也是沒有新內容，繼續對重定向、管道進行綜合訓練，題目如下：

??但是，我沒寫出來！所以這篇先放一個好兄弟的代碼，等過段時間不忙了再分析他的寫自己的，嘿嘿！代碼如下（因為不是一個人的代碼，所以代碼風格和前幾版都不太相同，學優點就ok）：

#include<stdlib.h> #include<stdio.h> #include<sys/types.h> #include<unistd.h> #include<sys/wait.h> #include<string.h> #include<sys/stat.h> #include<fcntl.h> char *command_begin; int commnd_count = 0; #define MAX_SIZE 1024 #define TRUE 1 #define MAX_ARGC 16 #define MAX_COMMANDS 64 #define MAX_S 64 typedef struct s_command {int argc;char *argv[MAX_ARGC];char *input; //用于重定向輸入 char *output; //用于重定向輸出 }s_command;s_command commands[MAX_COMMANDS]; int parse_command(char *command); int parse_commands(char *command); char** _splite(const char *command, char ch); void func_echo(char * opt); void mysys(struct s_command *c); void exec_pipe();int main(int argc,char *argv[]) { while(TRUE) {char ch[] =">";char *opt = (char *)malloc(sizeof(char)* MAX_SIZE);write(1,ch,strlen(ch));int size;size = read(0, opt, MAX_SIZE);if (size < 0) {printf("Read error\n");exit(0);}opt[size - 1] = '\0';command_begin = (char *)malloc(sizeof(char)*MAX_SIZE);strcpy(command_begin, opt);parse_commands(opt);if (commands[0].argv != NULL && !strcmp("exit",commands[0].argv[0]) ) {printf("exit\n");exit(0);}if (commnd_count == 1) {pid_t pi;pi = fork();if (pi == 0) {mysys(&commands[0]);exit(0);}wait(0);}else {pid_t pid;pid = fork();if (pid < 0) {printf("Error,create process error\n");exit(0);}else if (pid == 0) {exec_pipe();exit(0);}wait(NULL);}commnd_count = 0;memset(&commands,0,sizeof(commands)); }return 0; }int parse_command(char *command) {char *inner_ptr = NULL;int ar = 0;char *word;word = strtok_r(command, " ", &inner_ptr);while (word != NULL) {commands[commnd_count].argv[ar] = (char *)malloc(sizeof(char)*MAX_S);strcpy(commands[commnd_count].argv[ar], word);ar++;word = strtok_r(NULL, " ", &inner_ptr);}commands[commnd_count].argv[ar] = NULL;return ar; }int parse_commands(char *command) {char *outer_ptr = NULL;char *word;word = strtok_r(command, "|", &outer_ptr);while (word != NULL) {char buffer[100];strcpy(buffer, word);commands[commnd_count].argc = parse_command(buffer);commnd_count++;word = strtok_r(NULL, "|", &outer_ptr);}return commnd_count;}char** _splite(const char *command, char ch) {char * temp = (char *)malloc(sizeof(char *) * (strlen(command) + 1));char **rec;int count = 0;for (int i = 0; i < strlen(command); i++) {if (command[i] == ch) {temp[i] = '\0';count++;continue;}temp[i] = command[i];}temp[strlen(command) - 1] = '\0';rec = (char **)malloc(sizeof(char*)*(count + 1));count = 0;int st = 0;for (int i = 0; i < strlen(command); i++) {if (temp[i] == '\0') {rec[count] = (char *)malloc(sizeof(char) * sizeof(&temp[st]));strcpy(rec[count], &temp[st]);st = i + 1;count++;}}rec[count] = NULL;return rec; } void func_echo(char * opt) {char * temp = (char *)malloc(sizeof(char *) * (strlen(opt) + 1));for (int i = 0; i < strlen(opt); i++) {temp[i] = opt[i];}int sign = 0; // judge > front or behindchar *echo_s;char *file_name;for (int i = 4; i < strlen(opt); i++) {if (opt[i] == '>') {temp[i] = '\0';echo_s = (char *)malloc(sizeof(char)*(i));strcpy(echo_s, &temp[5]);sign = 1;}else if (sign == 1) {if (opt[i] == ' ') continue;file_name = (char *)malloc(sizeof(char)*(strlen(opt)));strcpy(file_name, &temp[i]);break;}}char ch[] = "\n";if (sign == 0) {echo_s = (char *)malloc(sizeof(char)*strlen(opt));strcpy(echo_s, &opt[5]);write(1, echo_s, strlen(echo_s));write(1, ch, strlen(ch));}else {int fd = creat(file_name, 0777);if (fd == -1) {puts("Create error");exit(0);}dup2(fd, 1);close(fd);write(1, echo_s, strlen(echo_s));write(1, ch, strlen(ch));} }void mysys(struct s_command *c) {char buff[MAX_SIZE];if (c->argv != NULL && !strcmp("pwd", c->argv[0])) {char *cwd = getcwd(buff, sizeof(buff));if (cwd == NULL) {printf("error\n");exit(-1);}else {printf("current dir: %s\n", cwd);}}else if (c->argv != NULL && !strcmp("cd", c->argv[0])) {if (c->argv[1] == NULL) {printf("parenter error\n");exit(0);}else {chdir(c->argv[1]);}}else if (c->argv != NULL && !strcmp("echo", c->argv[0])) {int p = fork();if (p == 0) {func_echo(command_begin);exit(0);}wait(NULL);}else {pid_t pid;pid = fork();if (pid < 0) {printf("Error,create process error\n");exit(0);}else if (pid == 0) {execvp(c->argv[0], c->argv);exit(0);}wait(NULL);}}void exec_pipe() {int fd[2];pipe(fd);pid_t pid;pid = fork();if (pid < 0) {printf("Error,create process error\n");exit(0);}else if (pid == 0) {dup2(fd[0], 0);close(fd[1]);close(fd[0]);mysys(&commands[1]);exit(0);}dup2(fd[1], 1);close(fd[1]);close(fd[0]);mysys(&commands[0]); }

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