系统编程 - kill，alarm，read，write

1、父进程杀死子进程

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <signal.h>
#include <unistd.h>

int main()
{
	pid_t pid;
	pid = fork();
	if(pid < 0)
	{
		perror("fork failed");
	}
	else if(pid == 0)
	{
		int i =0;
		for(i = 0; i < 5; i++)
		{
			printf("in child process\n");
			sleep(1);
		}
	}
	else
	{
		printf("in father process\n");
		sleep(2);
		printf("kill child process now\n");
		int nRet = kill(pid, SIGINT);
		printf("nRet = %d\n", nRet);
	}
	return 0;
}

2、定时自杀

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

int main()
{
	int sec = 0;
	sec = alarm(5);
	printf("sec = %d\n", sec);
	sleep(1);
	sec = alarm(5);
	printf("sec = %d\n", sec);
	while(1);
	return 0;
}

3、自己实现文件的拷贝cp

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

int main(int argc, char *argv[])
{
	int fd_src, fd_dest;
	char rdBuf[1024] = { 0 };
	int nRet;
	if( argc < 3 )
	{
		printf("parameter num error");
		return 0;
	}

	fd_src = open(argv[1], O_RDONLY);
	if( fd_src < 0 )
	{
		perror("open src");
		return 0;
	}
	fd_dest = open(argv[2], O_WRONLY|O_CREAT, 0666);
	if( fd_dest < 0 )
	{
		perror("open dest");
		return 0;
	}

	while(1)
	{
		nRet = read(fd_src, rdBuf, 1024);
		if( nRet <= 0)
		{
			break;
		}
		write(fd_dest, rdBuf, nRet);
	}
	close(fd_src);
	close(fd_dest);
	return 0;
}