自己動手寫shell命令之ls

標籤：unix環境進階編程   shell   

linux下ls命令（支援-R參數）的c語言實現：

#include <stdio.h>#include <sys/types.h>#include <dirent.h>#include <sys/stat.h>#include <pwd.h>#include <grp.h>#include <string.h>void do_ls(char *);void do_stat(char *,char *);void show_file_info(char *,struct stat *,char *);void mode_to_letters(int ,char []);char * uid_to_name(uid_t);char * gid_to_name(gid_t);int recursive = 0;int main(int argc,char * argv[]){int i;for(i = 1;i < argc;i++){if(strcmp(argv[i],"-R") == 0){recursive = 1;break;}}if(argc == 1 && recursive == 0)do_ls(".");else if(argc == 2 && recursive == 1)do_ls(".");else{int index = 1;while(argc > 1){if(strcmp(argv[index],"-R") != 0)do_ls(argv[index]);index++;argc--;}}return 0;}void do_ls(char * path){DIR * dir;struct dirent * direntp;if((dir = opendir(path)) != NULL){while((direntp = readdir(dir)) != NULL){char absolute_pathname[255];strcpy(absolute_pathname,path);strcat(absolute_pathname,"/");strcat(absolute_pathname,direntp->d_name);printf("%s\n",absolute_pathname);do_stat(absolute_pathname,direntp->d_name);}closedir(dir);}elsefprintf(stderr,"can't open %s",path);}void do_stat(char * absolute_filename,char * filename){struct stat  s;if(lstat(absolute_filename,&s) == -1)perror(absolute_filename);elseshow_file_info(absolute_filename,&s,filename);}void show_file_info(char * absolute_filename,struct stat * info,char * filename){char mode[11];mode_to_letters(info->st_mode,mode);printf("%s ",mode);printf("%d ",info->st_nlink);printf("%s ",uid_to_name(info->st_uid));printf("%s ",gid_to_name(info->st_gid));printf("%d ",info->st_size);printf("%.12s ",4+ctime(&info->st_mtime));printf("\n");if(recursive == 1){if(S_ISDIR(info->st_mode) && strcmp(filename,".") != 0 && strcmp(filename,"..") != 0)do_ls(absolute_filename);}}void mode_to_letters(int mode,char * c_mode){strcpy(c_mode,"----------");if(S_ISDIR(mode))c_mode[0] = 'd';if(S_ISCHR(mode))c_mode[0] = 'c';if(S_ISBLK(mode))c_mode[0] = 'b';if(mode & S_IRUSR)c_mode[1] = 'r';if(mode & S_IWUSR)c_mode[2] = 'w';if(mode & S_IXUSR)c_mode[3] = 'x';if(mode & S_IRGRP)                c_mode[4] = 'r';        if(mode & S_IWGRP)                c_mode[5] = 'w';        if(mode & S_IXGRP)                c_mode[6] = 'x';if(mode & S_IROTH)                c_mode[7] = 'r';        if(mode & S_IWOTH)                c_mode[8] = 'w';        if(mode & S_IXOTH)                c_mode[9] = 'x';if(mode & S_ISUID)c_mode[3] = 's';if(mode & S_ISGID)c_mode[6] = 's';if(mode & S_ISVTX)c_mode[9] = 's';}char * uid_to_name(uid_t uid){struct passwd * passwd_pointer;passwd_pointer = getpwuid(uid);return passwd_pointer->pw_name;}char * gid_to_name(gid_t gid){struct group * group_pointer;static char numstr[10];if((group_pointer = getgrgid(gid)) == NULL){sprintf(numstr,"%d",gid);return numstr;}return group_pointer->gr_name;}

自己動手寫shell命令之ls