在Ubuntu中使用C语言实现文件的拷贝功能

思路：
a.打开源文件和目标文件；
b.读取源文件的内容，写到目标文件；
c.关闭源文件和目标文件；

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <strings.h>

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

int main(){
    //open file
    int fd1 = open("./cpy_test1.c",O_RDONLY); 
    int fd2 = open("./cpy_test2.c",O_WRONLY| O_CREAT| O_TRUNC,0777);
    if(fd1 == -1){//error
        perror("open");
        return -1;
    }
    printf("fd1=%d\n",fd1);

    if(fd2 == -1){ //error
        perror("open");
        return -1;
    }
    printf("fd2=%d\n",fd2);

    //read file
    char buf[512] = {0};
    int rret = read(fd1,buf,sizeof(buf));
    if(rret == -1){//error
        perror("read");
        close(fd1);
        return -1;
    }
    printf("rret=%d\n",rret);
    
    //write file
    int wret = write(fd2,buf,sizeof(buf));
    if(wret == -1){ //error
        perror("write");
        close(fd2);
        return -1;
    }
    printf("wret=%d\n",wret);

    close(fd1); //关闭源文件
    close(fd2); //关闭目标文件

    return 0;
}