C语言 EAGAIN 是什么意思？

What does EAGAIN mean?

提问by David van Dugteren

As in the title what does EAGAIN mean?

正如标题中的 EAGAIN 是什么意思？

回答by Frédéric Hamidi

EAGAINis often raised when performing non-blocking I/O. It means "there is no data available right now, try again later".

EAGAIN通常在执行非阻塞 I/O时引发。意思是“目前没有可用数据，稍后再试”。

It might(or might not) be the same as EWOULDBLOCK, which means "your thread would have to block in order to do that".

它可能（或可能不）与 相同EWOULDBLOCK，这意味着“您的线程必须阻塞才能做到这一点”。

回答by turfx

Using man 2 intro | less -Ip EAGAIN:

使用man 2 intro | less -Ip EAGAIN：

     35 EAGAIN Resource temporarily unavailable.  This is a temporary condi-
         tion and later calls to the same routine may complete normally.

回答by wildplasser

What it means is less important. What it implies:

这意味着什么并不重要。它的含义：

• your system call failed
• nothing happened (system calls are atomic, and this one just did not happen)
• you couldtry it again (it could fail again, possibly with a different result)
• or you couldchoose otherwise.

• 你的系统调用失败
• 什么也没发生（系统调用是原子的，而这个只是没有发生）
• 你可以再试一次（它可能会再次失败，可能会有不同的结果）
• 或者你可以选择其他方式。

The whole thing about EAGAINis that your process is not blocked inside the system call; it has the right to choose: either retry or do something useful.

整件事EAGAIN是你的进程没有被系统调用阻塞；它有权选择：要么重试，要么做一些有用的事情。

回答by thelost

According to this, it means "Operation would have caused the process to be suspended."

根据这个，它的意思是“操作会导致进程暂停。”