如果脚本启动后连接了电缆，Python无法获得IP [英] Python not getting IP if cable connected after script has started

问题描述

我希望这不会进入超级用户领域.

I hope this doesn't cross into superuser territory.

所以我有一个嵌入式linux，系统进程自然很简单.我不太确定哪个系统进程会监视物理层并在插入网络电缆时启动dhcp客户端，但是我自己做了一个. ¨ 问题是，如果我有一个使用http连接的python脚本，并且在没有IP地址之前运行，它将永远无法建立连接.即使在我拥有有效的IP之后，python仍然具有

So I have an embedded linux, where system processes are naturally quite stripped. I'm not quite sure which system process monitors to physical layer and starts a dhcp client when network cable is plugged in, but i made one myself. ¨ The problem is, that if i have a python script, using http connections, running before i have an IP address, it will never get a connection. Even after i have a valid IP, the python still has

名称解析中的临时错误"

"Temporary error in name resolution"

那么，如何在不重新启动脚本的情况下使python实现新的可用连接呢?

So how can I get the python to realize the new connection available, without restarting the script?

或者，我是否缺少一些正常的程序，Linux在网络电缆连接上正常运行.

Alternatively , am I missing some normal procedure Linux runs normally at network cable connect.

我正在使用的dhcp客户端是udhcpc，而python版本是2.6.使用httplib进行连接.

The dhcp client I am using is udhcpc and python version is 2.6. Using httplib for connections.

推荐答案

类似httplib的声音/etc/resolv.conf会在您的DHCP客户端获得IP后更新.

Sounds like httplib caches /etc/resolv.conf which is updated after your DHCP client obtains an IP.

您可能会考虑编写一个包装器脚本，该脚本将等到获得IP地址后再调用您的python脚本.

You might consider writing a wrapper script that waits until an IP address is obtained, then calls your python script.

或者，您可以尝试在python脚本中不打开任何套接字连接，直到获得IP地址并更新/etc/resolv.conf.

Alternatively, you could try to, within your python script, not open any socket connections until you have acquired an IP address and /etc/resolv.conf updated.

修改

httplib使用socket.create_connection()，经过一些搜索，我发现做缓存 /etc/resolv.conf. (好吧，看来libc的嵌入式版本实际上是在进行缓存).

httplib uses socket.create_connection() which, after some searching, I found does cache /etc/resolv.conf. (Well, it seems that the embedded version of libc is actually doing the caching).

您可以尝试 SugarLabs的解决方案，尽管我可以没说这是有效的.

You could try SugarLabs' solution, although I can't speak to it's effectiveness.

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