黑马《linux基础编程》学习笔记（71到75）

七十一. makefile练习

题目：

问题1的解答： 

七十二. read , write函数写文件

read_write.c内容

#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdlib.h>

int main(int argc, const char* argv[])
{
    int fd = open("english.txt", O_RDONLY);
    if(fd == -1)
    {
        perror("open error");
        exit(1);
    }

    // 读文件
    char buf[1024];
    int len = read(fd, buf, sizeof(buf));

    // 写文件
    int fd1 = open("temp", O_WRONLY | O_CREAT, 0664);
    if(fd1 == -1)
    {
        perror("open error");
        exit(1);
    }

    while( len > 0 )
    {
        // 写文件
        int ret = write(fd1, buf, len);
        len = read(fd, buf, sizeof(buf));
    }
    close(fd);
    close(fd1);

    return 0;
}

七十三. perror和errno

 

 

 七十四. lseek实现文件拓展

 

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>

int main(int argc, const char* argv[])
{
    int fd = open("copy", O_RDWR);
    if(fd == -1)
    {
        perror("open error");
        exit(1);
    }

    // 拓展文件
    int len = lseek(fd, 0, SEEK_END);
    printf(" file len = %d\n", len);

    lseek(fd, 100000, SEEK_END);
    write(fd, "a", 1);

    close(fd);
    return 0;
}

七十五. 阻塞读终端

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

// ▒▒▒▒▒▒ն▒
int main(void)
{
        char buf[10];
        int n;
        n = read(STDIN_FILENO, buf, 10);
        if (n < 0)
        {
                perror("read STDIN_FILENO");
                exit(1);
        }
        write(STDOUT_FILENO, buf, n);
        return 0;
}

[root@VM_0_15_centos Block]# ls
block  block_read.c  time  timeout_unblock_read.c  unblock  unblock_read.c

[root@VM_0_15_centos Block]# gcc block_read.c -o block_app

[root@VM_0_15_centos Block]# ls
block      block_read.c  timeout_unblock_read.c  unblock_read.c
block_app  time          unblock

[root@VM_0_15_centos Block]# ./block_app
hello,worldabs
hello,worl[root@VM_0_15_centos Block]# dabs
-bash: dabs: command not found