有過linux 基礎 都知道 ls 命令的作用

下面給出實現程式碼

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <time.h>
#include <dirent.h>
int  fun1(char *dir,char *filename)
{
	struct stat buf;
	char out[100];
	if(stat(dir,&buf)<0)
	{
		perror("stat");
		return (-1);

	}

	switch(buf.st_mode & S_IFMT)
	{
	case S_IFREG:	
		printf("-");
		break;
	case S_IFDIR:	
		printf("d");
		break;
	case S_IFCHR:	
		printf("c");
		break;
	case S_IFBLK:	
		printf("b");
		break;
	case S_IFIFO:	
		printf("p");
		break;
	case S_IFLNK:	
		printf("l");
		break;
	case S_IFSOCK:	
		printf("s");
		break;
	}

	int n;
	for(n=8;n>=0;n--)
	{
		if(buf.st_mode&(1<<n))
		{
			switch(n%3)
			{
			case 2:
				printf("r");
				break;
			case 1:
				printf("w");
				break;
			case 0:
				printf("x");
					break;
			default:
				break;

			}
		}
		else
		{
			printf("-");
		}
	}
	
	
	printf(" %d",buf.st_nlink);
	
	struct passwd *pw;
	pw = getpwuid(buf.st_uid);
	printf(" %s",pw->pw_name);

	struct group *gr;
	gr = getgrgid(buf.st_gid);
	printf(" %s",gr->gr_name);

	printf(" %ld",buf.st_size);
	

	struct tm *t;
	t = localtime(&buf.st_atime);
	printf(" %d-%d-%d %d:%d",t->tm_year+1900,
							t->tm_mon+1,
							t->tm_mday,
							t->tm_hour,
							t->tm_min);
   printf(" %s ",filename);	

	
	   
	if(S_ISLNK(buf.st_mode))
	{
		printf(" -> ");
		if(readlink(filename,out,100)==-1)
		{

		}
		printf("%s",out);

	}
	printf("\n");
	return 0;
}


int main(int argc ,char **argv)
{
	char w[100];
	memset(w,0,100);

	if(argc<2)
		strcpy(w,"./");

	else
		strcpy(w,argv[1]);
	struct stat buf;
	char name[100];
	if(stat(w,&buf)<0)
	{
		fprintf(stderr,"stat error:%s\n",strerror(errno));
		return -1;
	}
	
	if(S_ISDIR(buf.st_mode))
	{
		DIR *dir;
		dir = opendir(w);
		struct dirent *pdr;
		while ((pdr = readdir(dir))!=NULL)
		{
			if(pdr->d_name[0]=='.')
			{
			}
			else
			{
				printf(" dir:%s \n",pdr->d_name);
				memset(name,0,100);
				strcpy(name,w);
			//	strcat(name,"/");
				strcat(name,pdr->d_name);
				fun1(name,pdr->d_name);
			}
			
		}
	}
	else
	{
		fun1(w,w);
	}
	return 0;
}