linux 文件操作 --copy_file

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代码：

ngnsvr9 [** NONE **]/home/xionghailong/example $ cat copy_file.c
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>

#define BUFFER_SIZE 1024
#define SRC_FILE_NAME "src_file"
#define DEST_FILE_NAME "dest_file"
#define OFFSET 10240

int main()
{
        int src_file, dest_file;
        unsigned char buff[BUFFER_SIZE];
        int real_read_len;

        src_file = open(SRC_FILE_NAME, O_RDONLY);

        dest_file = open(DEST_FILE_NAME, O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
        if (src_file < 0 || dest_file < 0)
        {
                printf("Open file error\n");
                exit(1);
        }

        lseek(src_file, -OFFSET, SEEK_END);

        while ((real_read_len = read(src_file, buff, sizeof(buff))) > 0)
        {
                write(dest_file, buff, real_read_len);
        }

        close(dest_file);
        close(src_file);

        return 0;
}

源文件：

ngnsvr9 [** NONE **]/home/xionghailong/example $ cat src_file
123456123456123456123456123456123456123456123456123456123456123456123456

编译运行结果：

ngnsvr9 [** NONE **]/home/xionghailong/example $ gcc copy_file.c -o copy_file
ngnsvr9 [** NONE **]/home/xionghailong/example $ ./copy_file
ngnsvr9 [** NONE **]/home/xionghailong/example $ cat dest_file
123456123456123456123456123456123456123456123456123456123456123456123456

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