Linux 使用 O_RDWR 与 O_RDONLY | O_WRONLY
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Using O_RDWR vs O_RDONLY | O_WRONLY
提问by sircodesalot
In my simple program:
在我的简单程序中：
#include <iostream>
#include <unistd.h>
#include <fcntl.h>
#include <sstream>
using namespace std;
int main(int argc, char *argv[]) {
stringstream ss;
ss << "What does the quick brown fox say?" << endl;
int file_descriptor = open("/dev/tty", O_RDONLY | O_WRONLY);
write(file_descriptor, ss.str().c_str(), ss.str().size());
}
I open the terminal stream using the combination O_RDONLY| O_WRONLY, and this seems to work fine. I get that you shoulduse O_RDWRbecause it makes clearer semantic sense, but my question is why bother creating a whole other flag if joining two existing flags already works? Is there some historical reason for this, or am I just overlooking something, and this really doesn't actually work?
我使用组合打开终端流O_RDONLY| O_WRONLY，这似乎工作正常。我知道您应该使用O_RDWR它，因为它具有更清晰的语义，但我的问题是，如果连接两个现有标志已经有效，为什么还要创建一个完整的其他标志？这有什么历史原因，还是我只是忽略了一些东西，而这实际上不起作用？
采纳答案by Mats Petersson
O_RDONLY | O_WRONLY(at least on my Linux machine) is not the same thing as O_RDWR.
O_RDONLY | O_WRONLY（至少在我的 Linux 机器上）与O_RDWR.
#define O_RDONLY 00
#define O_WRONLY 01
#define O_RDWR 02
The fact that it works seems like a bug/feature/coincidence rather than "it works because it should work that way".
它工作的事实似乎是一个错误/功能/巧合，而不是“它工作是因为它应该以这种方式工作”。
