Linux练习（系统调用复制文件）

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

int main()
{
        char block[1024];
        int in,out;
        int nread;

        in=open("file.in",O_RDONLY);
        out=open("file.out",O_WRONLY|O_CREAT,S_IRUSR|S_IWUSR);
        while ((nread=read(in,block,sizeof(block)))>0)
                write(out,block,nread);
        exit(0);

}