参见附图，改进你的ls的实现。提交代码运行截图和码云链接。

#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)  

// 展示单个文件的详细信息
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);
    }
}  

// 解析一个单词参数，如-l，-i
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; // 默认为无参数ls
        int have_file_param = 0; // 是否有输入文件参数
        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);
        }
    }
}

原文地址：https://www.cnblogs.com/fakerli/p/12105440.html