setuid_example.c

linux下的程序开发（C语言实现）：本程序主要实现linux下进程的管理

#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>

int main(int argc,char argv[])
{
	int i;
	printf("now the uid is %d\n",getuid());
	if((i=access("/etc/exports",W_OK))==-1)
	{
		perror("access");
		exit(EXIT_FAILURE);
	}
	else
	{
		 printf("the UID have write permission\n");
	}
	printf("now change the uid\n");		 
	if(i=setuid(500)==-1)
	{
		perror("setuid");
		exit(EXIT_FAILURE);
	}
	
	printf("now the uid is %d\n",getuid());
	printf("now the euid is %d\n",geteuid());
	if((i=access("/etc/exports",W_OK))==-1)
	{
		perror("access");
		exit(EXIT_FAILURE);
	}
	else
	{
		 printf("the UID have write permission\n");
	}
			 
	return 0;
}