子进程会影响父进程的环境？ [英] Can the child process affect parent process' environment?

问题描述

什么是的孩子继承了父母的环境的是什么意思？通过复制整个环境继承，或通过接收指向同一个环境中继承（不知）？

What does "the child inherits the parent's environment" mean? Inherits by copying the whole environment, or inherits by receiving pointer to the same environment (somehow)?

下面是我的情况：

1. 我有一个正在运行的进程 P 与它自己的环境（变量）


2. 在某些时候， P 执行叉


3. 在 0 的 if语句（又名子进程中的 C ）的 execv 执行


4. 这两个进程将继续独立运行。

1. I have a running process P with its own environment (variables)
2. At some point, P executes fork
3. In the 0-clone of the if-statement (a.k.a. in the child process C), an execv is executed
4. Both processes continue running independently.

所以，在有些时候，应用程序停止正常工作。其原因是 - 破的环境。

So, in some moment, the application stops working fine. And the reason is - "broken" environment.

有趣的是，这两个环境有所改变。当我开始父进程和执行

The interesting part is, that both environments are changed.. When I start the parent process and execute

$ cat /proc/PID/environ

为 - 家长和过程，一切都很好。几小时后，应用程序停止工作，当我执行上面再行（检查环境），两者都改变​​，大量的环境变量的缺失 - 只有标准的是有（如 PWD ，首页， USER ，等等）。

这怎么可能？并在可能的问题 - 在儿童或父

How is this possible? And where could the the problem - in the child or in the parent?

的 修改 的感谢所有的答案，从+1我，因为他们是正确的（@caf，@Saphrosit和@R ..）。这样做的原因问题真的很傻。

Thanks all for the answers, +1 from me, as they were all correct ( @caf, @Saphrosit and @R..). The reason for this issue is really silly..

所有的环境变量放在 / etc / profile文件这是登录后（即..我不知道）执行。

All environment variables were placed in /etc/profile which is executed AFTER LOGIN (that.. I didn't know).

那么，它的出现，这个问题发生在机器的重新启动。因此，在启动时，应用程序将再次启动，但 / etc / profile文件/ 是不会执行/读取。这会导致不良行为。这就是为什么这个问题上手动重启消失 - 一旦根已登录（通过 SSH ），环境变量从的/ etc /型材被读取，当父进程重新启动（由根），这一切都很好 - 环境变量继承。

Well, it appeared, that the issue have happened on restart of the machine. So, on start-up, the application is started again, but /etc/profile/ is not executed/read. And this causes the bad behavior. And that's why the problem disappears on manual restart - once a root is logged in (through ssh), the environment variables from /etc/profiles are read, and when the parent process is restarted (by root), it's all fine - the environment variables are inherited.

愚蠢的错误。

推荐答案

这孩子在叉的瞬间继承父的环境的副本（）。在任一过程中对环境的后续变化不影响其他

The child inherits a copy of the parent's environment at the moment of the fork(). Subsequent changes to the environment in either process do not affect the other.

您可以改变这一点的唯一方法是做一些很奇怪的，像放置在 MAP_SHARED 区域环境，或者使用 ptrace的（） 。你知道，如果你做了这样的事情，虽然。

The only way you could alter this is by doing something very strange, like placing the environment in a MAP_SHARED area, or using ptrace(). You'd know it if you did something like this, though.

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