#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h> //包含open/read/write函數

//命令：./a.out file
//讀取file中的內容進入buffer,並打印出來
int main(int argc, char *argv[])
{
    int fd;    //文件描述符
    char buffer[1024];
    int ret;

    fd = open(argv[1],O_RDONLY); //只讀模式
    if(fd<0
 
) //打開失敗，返回－1
    {
        printf("open error!\n");
        return -1;
    }

    ret = read(fd,buffer,sizeof(buffer)-1);
    if(ret<0)
    {
        printf("read error!\n");
        return -1;
    }

    printf("readCharNum=%d\n",ret);
    printf("file:\n%s",buffer);

}

open、read操作文件