一、代码

#include <stdio.h>  
#include <sys/types.h>  
#include <dirent.h>  
#include <sys/stat.h>  
#include <pwd.h>  
#include <grp.h>  
#include <unistd.h>  
#include <string.h>  
#define LS_NONE 0  
#define LS_L 101  
#define LS_R 102  
#define LS_D 103  
#define LS_I 104  
#define LS_A 200  
#define LS_AL (LS_A+LS_L)  
#define LS_AI (LS_A+LS_I)  
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[],int mode)  
{  
    DIR* dir_ptr;  
    struct dirent* direntp;  
      
    if ((dir_ptr = opendir(dirname)) == NULL)  
    {  
        fprintf(stderr, "ls2: cannot open %s \n", dirname);  
    }  
    else  
    {  
        if(mode==LS_D)  
        {  
            printf("%s\n", dirname);  
        }  
        else  
        {  
            char dirs[20][100];  
            int dir_count = 0;  
                  
            while ((direntp = readdir(dir_ptr)) != NULL)  
            {  
      
                if(mode < 200 && direntp->d_name[0]=='.')  
                {  
                    continue;  
                } 
                char complete_d_name[200];  // 文件的完整路径  
                strcpy (complete_d_name,dirname);  
                strcat (complete_d_name,"/");  
                strcat (complete_d_name,direntp->d_name);  
                      
                struct stat info;  
                if (stat(complete_d_name, &info) == -1)  
                {  
                    perror(complete_d_name);  
                }  
                else  
                {  
                    if(mode == LS_L||mode == LS_AL)  
                    {  
                        show_file_info(direntp->d_name, &info);  
                    }  
                    else if(mode == LS_A||mode == LS_NONE||mode == LS_I||mode == LS_AI)  
                    {  
                        if(mode == LS_I||mode == LS_AI)  
                        {  
                            printf("%llu ", direntp->d_ino);  
                        }  
      
                        printf("%s\n", direntp->d_name);  
                    }  
                    else if(mode == LS_R)  
                    {  
      
                        if(S_ISDIR(info.st_mode))  
                        {  
                            printf("%s\n", direntp->d_name);  
                            strcpy (dirs[dir_count],complete_d_name);  
                            dir_count++;  
                        }  
                        else  
                        {  
                            printf("%s\n", direntp->d_name);  
                        }  
                    } 
                }  
            }  
            if(mode == LS_R)  
            {  
                int i=0;  
                printf("\n");  
                for(;i<dir_count;i++){  
                printf("%s:\n", dirs[i]);  
                do_ls(dirs[i],LS_R);  
                printf("\n");  
                }  
            }  
        }  
        closedir(dir_ptr);  
    }  
}  
int analyzeParam(char* input){  
    if(strlen(input)==2)  
    {  
        if(input[1]=='l') return LS_L;  
        if(input[1]=='a') return LS_A;  
        if(input[1]=='d') return LS_D;  
        if(input[1]=='R') return LS_R;  
        if(input[1]=='i') return LS_I;  
    }  
    else if(strlen(input)==3)  
    {  
        if(input[1]=='a'&& input[2]=='l') return LS_AL;  
        if(input[1]=='a'&& input[2]=='i') return LS_AI;  
    }  
    return -1;  
}     
int main(int ac,char* av[])  
{  
    if(ac == 1)  
    {  
        do_ls(".",LS_NONE);  
    }  
    else  
    {  
        int mode = LS_NONE;  
        int have_file_param = 0;  
        while(ac>1)  
        {  
            ac--;  
            av++;  
            int calMode = analyzeParam(*av);  
            if(calMode!=-1)  
            {  
                mode+=calMode;  
            }  
            else  
            {  
                have_file_param = 1;  
                do  
                {  
                    printf("%s:\n", *av);  
                    do_ls(*av,mode);  
                    printf("\n");  
                    ac--;  
                    av++;  
                }while(ac>=1);  
            }  
        }  
        if (!have_file_param)  
        {  
            do_ls(".",mode);  
        }  
    }       
}

二、截图