Linux系统函数_read和write实现文件拷贝功能 代码

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

#define N 1024

int main(int argc, char const* argv[])
{
    int fd, fd_out;
    int n;
    char buf[N];

    fd = open(argv[1], O_RDONLY);
    if(fd < 0)
    {
        perror("open 1 error");
        exit(1);
    }

    fd_out = open(argv[2], O_WRONLY|O_CREAT|O_TRUNC, 0644);
    if(fd_out < 0)
    {
        perror("open 2 error");
        exit(1);
    }
    while((n = read(fd, buf, N)))
    {
        if(n < 0)
        {
            perror("read error");
            exit(1);
        }
        write(fd_out, buf, n);
    }
    close(fd);
    close(fd_out);
    return 0;
}