Linux C变成小例子——实现ls命令

来源：互联网发布：nginx的特点编辑：程序博客网时间：2024/06/05 19:42
/* * ls2.c * *  Created on: Dec 30, 2013 *      Author: fedora */#include <stdio.h>#include <sys/types.h>#include <dirent.h>#include <sys/stat.h>#include <pwd.h>#include <grp.h>void show_file_info(char* filename, struct stat* info_p) {char* uid_to_name(), *ctime(), *gid_to_name(), *filemode();void mode_to_letters();char modestr[11];mode_to_letters(info_p->st_mode, modestr);printf("%s", modestr);printf(" %4d", (int) info_p->st_nlink);printf(" %-8s", uid_to_name(info_p->st_uid));printf(" %-8s", gid_to_name(info_p->st_gid));printf(" %8ld", (long) info_p->st_size);printf(" %.12s", 4 + ctime(&info_p->st_mtime));printf(" %s\n", filename);}void mode_to_letters(int mode, char str[]) {strcpy(str, "----------");if (S_ISDIR(mode)) {str[0] = 'd';}if (S_ISCHR(mode)) {str[0] = 'c';}if (S_ISBLK(mode)) {str[0] = 'b';}if ((mode & S_IRUSR)) {str[1] = 'r';}if ((mode & S_IWUSR)) {str[2] = 'w';}if ((mode & S_IXUSR)) {str[3] = 'x';}if ((mode & S_IRGRP)) {str[4] = 'r';}if ((mode & S_IWGRP)) {str[5] = 'w';}if ((mode & S_IXGRP)) {str[6] = 'x';}if ((mode & S_IROTH)) {str[7] = 'r';}if ((mode & S_IWOTH)) {str[8] = 'w';}if ((mode & S_IXOTH)) {str[9] = 'x';}}char* uid_to_name(uid_t uid){struct passwd* getpwuid(),* pw_ptr;static char numstr[10];if((pw_ptr = getpwuid(uid)) == NULL){  sprintf(numstr,"%d",uid);  return numstr;}else{return pw_ptr->pw_name;}}char* gid_to_name(gid_t gid){struct group* getgrgid(),* grp_ptr;static char numstr[10];if(( grp_ptr = getgrgid(gid)) == NULL){sprintf(numstr,"%d",gid);return numstr;}else{return grp_ptr->gr_name;}}void do_ls(char dirname[]) {DIR* dir_ptr;struct dirent* direntp;if ((dir_ptr = opendir(dirname)) == NULL) {fprintf(stderr, "ls2: cannot open %s \n", dirname);} else {while ((direntp = readdir(dir_ptr)) != NULL) {dostat(direntp->d_name);}close(dir_ptr);}}void dostat(char* filename) {struct stat info;if (stat(filename, &info) == -1) {perror(filename);} else {show_file_info(filename, &info);}}int main(int ac,char* av[]){if(ac == 1){do_ls(".");}else{while(--ac){printf("%s: \n",*++av);do_ls(*av);}}}
输出的结果如下图所示：
1 0