为什么在删除目标文件后成功写入文件描述符?

问题描述

代码:

int main(int argc, char **argv)
{
    int fd = open("test.txt", O_CREAT|O_RDWR, 0200|0400);
    if(fd == -1)
    {
        printf("failure to oepn");
        exit(-1);
    }
    int iRet = write(fd, "aaaaaaaaaa", 10);

    if(iRet == -1)
    {
        printf("failure to writer");
        exit(-1);
    }
    sleep(10);
    printf("You must remove");
    iRet = write(fd, "bbbbbbbbbb", 10);

    if(iRet == -1)
    {
        printf("failure to after writer");
        exit(-1);
    }

   exit(0);
}

在sleep()期间，您删除了test.txt，但是该过程写入成功！为什么?如果日志为"Singleton"实例，则删除磁盘上的文件.写入成功，但是却什么也没得到.

during the sleep(), you delete the test.txt, but the process write successful!why?if a log "Singleton" instance, you remove the file on the disk.write is successful, but you can get nothing.

class log
{
public:
    void loggerWriter(std::string str);
    int fd;
};

log::log(std::string filename):fd(-1)
{
    fd = open(filename.c_str(), O_CREAT|)
    //...
}

log::loggerWriter(std::string str)
{
    writer(fd, str.c_str(), str.size());
}

int main()
{
    log logger("text.txt");
    //...
    //I want to know the text.txt the text.txt have delete on the disk or not.
    //if delete i can create another file to log.
}

取消链接"无法解决此问题.

"unlink" cann't solve this problem.

推荐答案

unlink(2)的手册页明确指出:

如果名称是文件的最后链接，但任何进程仍具有文件打开文件将一直存在，直到最后一个文件引用它的描述符已关闭.

If the name was the last link to a file but any processes still have the file open the file will remain in existence until the last file descriptor referring to it is closed.

caf 在注释中很好地指出:

As caf excellently notes in the comments:

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