Linux系统命令，手动编写实现ls -l

添加如下的四个C语言函数代码，实现四个功能，使得显示内容与系统自带的ls更接近。

void mode_to_char(int mode,char str[])

void mode_to_char(int mode,char str[])
{
    strcpy(str,"----------");
  //  mode_t newmode = mode & 07777;//get the last four digits
   // int i=0;
//judge user's 
    if(mode & S_IRUSR)str[1]='r';
    if(mode & S_IWUSR)str[2]='w';
    if(mode & S_IXUSR)str[3]='x';
//judge group's
    if(mode & S_IRGRP)str[4]='r';
    if(mode & S_IWGRP)str[5]='w';
    if(mode & S_IXGRP)str[6]='x';
//judge other's
    if((mode & S_IROTH)==S_IROTH)str[7]='r';
    if(mode & S_IWOTH)str[8]='w';
    if(mode & S_IXOTH)str[9]='x';
}

char* uid_to_name(int uid)

#include
char* uid_to_name(uid_t uid)
{
	struct passwd * pw_ptr;//Gets the username based on the user id
	pw_ptr = getpwuid(uid);
	return pw_ptr->pw_name;
}

char* gid_to_name(gid_t gid)

#include
char* gid_to_name(gid_t gid)
{
	struct group * grp_ptr;//Gets the group name based on the group id
	grp_ptr = getgrgid(gid);
	return grp_ptr->gr_name;
}

C 库函数 char *ctime(const time_t *timer)
返回一个表示当地时间的字符串，当地时间是基于参数 timer。
返回的字符串格式如下： Www Mmm dd hh:mm:ss yyyy 其中，Www 表示星期几，Mmm 是以字母表示的月份，dd 表示一月中的第几天，hh:mm:ss 表示时间，yyyy 表示年份。
“4+”是因为要跳过前四位表示星期的数，
“%.12s”表示打印十二位宽的右对齐字符

printf("%.12s ",4+ctime(&buf->st_mtime));

#include
#include
#include
#include

void show_stat_info(char *,struct stat * );
void mode_to_char(int ,char str[]);
char* uid_to_name(uid_t );
char* gid_to_name(gid_t );
//char* gid_to_name(int gid)

int main(int ac,char *av[])
{
    struct stat info;
    if(ac>1)
        if(stat(av[1], &info)!= -1)
	{
            show_stat_info(av[1],&info);
	   // mode_to_char(buf->st_mode,a);
            return 0;
        }
        else
            perror(av[1]);
    return 1;
}

show_stat_info(char *fname,struct stat * buf)
{
    char * uid_to_name(), * gid_to_name(),*ctime();
    void mode_to_char();
    char modestr[11];
    mode_to_char(buf->st_mode,modestr);
    printf("%s ",modestr);
    printf("%d ",(int)buf->st_nlink);
    printf("%s ",uid_to_name(buf->st_uid));
    printf("%s ",gid_to_name(buf->st_gid));
    printf("%ld ",(long)buf->st_size);
    printf("%.12s ",4+ctime(&buf->st_mtime));
    printf("%sn",fname);
//+4: Removes the display of the day of the week
//%.12s: Print 12 aligned characters
}

#include
char* uid_to_name(uid_t uid)
{
	struct passwd * pw_ptr;//Gets the username based on the user id
	pw_ptr = getpwuid(uid);
	return pw_ptr->pw_name;
}

#include
char* gid_to_name(gid_t gid)
{
	struct group * grp_ptr;//Gets the group name based on the group id
	grp_ptr = getgrgid(gid);
	return grp_ptr->gr_name;
}

void mode_to_char(int mode,char str[])
{
    strcpy(str,"----------");
  //  mode_t newmode = mode & 07777;//get the last four digits
   // int i=0;
//judge user's 
    if(mode & S_IRUSR)str[1]='r';
    if(mode & S_IWUSR)str[2]='w';
    if(mode & S_IXUSR)str[3]='x';
//judge group's
    if(mode & S_IRGRP)str[4]='r';
    if(mode & S_IWGRP)str[5]='w';
    if(mode & S_IXGRP)str[6]='x';
//judge other's
    if((mode & S_IROTH)==S_IROTH)str[7]='r';
    if(mode & S_IWOTH)str[8]='w';
    if(mode & S_IXOTH)str[9]='x';
}