1.孤儿进程：没有父进程的进程，父进程退出，子进程不退出。

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, const char *argv[])
{
	int a=10;
	pid_t cpid = fork();
	if(cpid>0)
	{
		printf("cpid=%d a=%d %p\n",cpid,a,&a);
	}
	else if(0==cpid)
	{
		while(1)
		{
			sleep(1);
		}
	}
	else
	{
		perror("fork");
		return -1;
	}
	return 0;
}

2.僵尸进程：父进程不退出，子进程退出。

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, const char *argv[])
{
	int a=10;
	pid_t cpid = fork();
	if(cpid>0)
	{
		while(1)
		{
			sleep(1);
		}
	}
	else if(0==cpid)
	{
		printf("cpid=%d a=%d %p\n",cpid,a,&a);
	}
	else
	{
		perror("fork");
		return -1;
	}
	return 0;
}

3.外部输入一个路径，要求显示该路径下，所有文件的详细信息，除了隐藏文件。

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>
#include <string.h>
#include <pwd.h>
#include <grp.h>
#include <fcntl.h>
#include <dirent.h>
 
void Get_Permission(mode_t mode)
{
	char per[]="rwx";
	for(int i=0;i<9;i++)
	{
		if((mode & (0400>>i))==0)
		{
			putchar('-');
			continue;
		}
		putchar(per[i%3]);
	}
}
 
int getFileType(mode_t m)
{
	switch(m&S_IFMT)
	{
	case S_IFSOCK: putchar('s');  break;
	case S_IFLNK:  putchar('l');  break;
	case S_IFREG:  putchar('-');  break;
	case S_IFDIR:  putchar('d');  break;
	case S_IFBLK:  putchar('b');  break;
	case S_IFCHR:  putchar('c');  break;
	case S_IFIFO:  putchar('p');  break;
	default:  printf("类型提取失败\n");
	}
	return 0;
}
 
void getfileUserName(uid_t uid)
{
	struct passwd *pwd=getpwuid(uid);
	if(NULL==pwd)
	{
		perror("getpwuid");
		return;
	}
	printf("%s ",pwd->pw_name);
	return;
}
 
void getfileGroupName(gid_t gid)
{
	struct group *grp=getgrgid(gid);
	if(NULL==grp)
	{
		perror("getgrgid");
		return;
	}
	printf("%s ",grp->gr_name);
	return;
}
 
int main(int argc, const char *argv[])
{
	if(argc<2)
	{
		fprintf(stderr,"请输入文件名\n");
		return -1;
	}
 
	DIR* dp = opendir(argv[1]);
	if(NULL == dp)
	{
		perror("opendir");
		return -1;
	}
	struct dirent* rp = NULL;
	while(1)
	{
		rp = readdir(dp);
		if(NULL == rp)
		{
			perror("readdir");
			break;
		}
		char filename[30]="";
        strcat(filename,argv[1]);
        strcat(filename,rp->d_name);
		if(rp->d_name[0] != '.')
		{
			struct stat buf;
			char copy[20]="";
			strcpy(copy,argv[1]);
			if(stat(strcat(copy,rp->d_name),&buf)<0)
			{
				perror("stat");
				return -1;
			}
			getFileType(buf.st_mode);
			printf(" ");
			Get_Permission(buf.st_mode);
			printf(" ");
			printf("%lu ",buf.st_nlink);
			getfileUserName(buf.st_uid);
			getfileGroupName(buf.st_gid);
			printf("%ld ",buf.st_size);
			struct tm* info = localtime(&buf.st_ctime);
			if(NULL==info)
			{
				return -1;
			}
			char *Month[12] = {"一月", "二月", "三月", "四月", "五月", "六月","七月", "八月", "九月", "十月", "十一月", "十二月"};
			printf("%s %02d %02d:%02d",\
					Month[info->tm_mon],info->tm_mday,\
					info->tm_hour,info->tm_min);
			printf(" %s\n",rp->d_name);
		}
	}
	closedir(dp);
	return 0;
}