本文章主要講述Linux環境下檔案的讀寫操作，使用到的函式有open、read、write、lseek。
open:用於開啟或者建立檔案。
read:從檔案中讀指定位元組的資料到記憶體中。
write：講記憶體中資料寫入到檔案中。
lseek：可以改變當前檔案偏移量。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

int main()
{
char read_file[] = "/home/imx/shares/open/read.bmp";
char write_file[] = "/home/imx/shares/open/write.bmp";
int file_len = 0;
int file_total = 0;
int read_len = 0;
char buf[1024] = {0};
int read_fd = open(read_file,O_RDWR);
int write_fd = open(write_file,O_RDWR|O_TRUNC |O_CREAT,00777);
if(read_fd < 0 || write_fd < 0 )
{
printf("file open error\n");
return 1;
}
file_len = (int)lseek(read_fd,0,SEEK_END);//get file total size
file_total = file_len;
printf("file_total:%d\n",file_total);
lseek(read_fd,0,SEEK_SET);
printf("read start\n");
while(read_len = read(read_fd,buf,1024))//file read
{
write(write_fd,buf,read_len);//file write
file_len = file_len - read_len;
memset(buf,0,1024);
}
printf("read and write end\n");
if(file_len != 0)//check file read write
{
close(read_fd);
close(write_fd);
printf("error:read!=write\n");
return 1;
}
close(read_fd);
close(write_fd);
return 0;

}