OSLab课堂作业1

 
 

日期：2019/3/16

作业：实现命令cat, cp, echo。

myecho命令

#include <stdio.h> int main(int argc, char *argv[]) {     int i = 0;     printf("argument count = %d\n", argc);     for (; i < argc; i++)         printf("%s\n", argv[i]);     return 0; }

 
 

mycat命令

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/stat.h> #include <fcntl.h> static char buf[256] = {0}; int main(int argc, char *argv[]) {     printf("Running program is %s\n", argv[0]);     printf("Argument count is %d\n", argc);     printf("File name is %s\n", argv[1]);     int file_desc = open(argv[1], O_RDONLY);     if (file_desc == -1)     {         perror("file is not existed!");         exit(EXIT_FAILURE);     }     int flag = read(file_desc, buf, 255);     while (flag != 0 && flag != -1)     {         printf("%s", buf);         memset(buf, 0, sizeof(buf));         flag = read(file_desc, buf, 255);     }     return 0; }

 
 

mycp命令

不支持dst为目录的cp命令。

#include <stdio.h> #include <stdlib.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> static char buf[256] = {0}; int main(int argc, char *argv[]) {     printf("src is %s\n", argv[1]);     printf("dst is %s\n", argv[2]);     int src = open(argv[1], O_RDONLY);     if (src == -1)     {         perror("file doesn't exist!\n");         exit(EXIT_FAILURE);     }     int dst = open(argv[2], O_RDWR | O_CREAT);     int flag = read(src, buf, 255);     while (flag != 0 && flag != -1)     {         write(dst, buf, 255);         memset(buf, 0, sizeof(buf));         flag = read(src, buf, 255);     }     return 0; }

 

mycp2命令

支持dst为目录。

#include <sys/types.h> #include <dirent.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> static char buf[256] = {0}; void cp_to_file(int src, int dst) {     int flag = read(src, buf, 255);     while (flag != 0 && flag != -1)     {         write(dst, buf, flag);         memset(buf, 0, sizeof(buf));         flag = read(src, buf, 255);     }     close(src);     close(dst); } int main(int argc, char *argv[]) {     printf("src is %s\n", argv[1]);     printf("dst is %s\n", argv[2]);     int src = open(argv[1], O_RDONLY);     if (src == -1)     {         perror("file doesn't exist!\n");         exit(EXIT_FAILURE);     }     int dst;     DIR *pdir = opendir(argv[2]);     if (pdir == NULL)     { //dst is file         dst = open(argv[2], O_RDWR | O_CREAT);         cp_to_file(src, dst);     }     else     { //dst is dir         printf("%s is a dir\n", argv[2]);         char temp[256];         strcpy(temp, argv[2]);         if (temp[strlen(temp) - 1] != '/')             strcat(temp, "/");         strcat(temp, argv[1]);         puts(temp);         dst = open(temp, O_RDWR | O_CREAT);         cp_to_file(src, dst);     }     return 0; }