histfile 变量用来指定存储命令执行历史的文件；默认设置是 $HOME/.history。

The histfile variable lets the user specify the name of the file where the command execution history should be stored; the default is $HOME/.history.

youdao

历史应用程序(即很过时的遗留代码)有时会直接引用这些全局变量，但会在编译过程中产生错误，因为它们的声明并不一致。

Historical applications (that is, horribly outdated legacy code) sometimes refer to these directly, but produce errors during compilation because they're declared inconsistently.

youdao

历史上，很多攻击利用的是命令shell处理IFS环境变量的方法，但是当今大部分的shell(包括GNU bash)已经经过了修改，从而使IFS难以利用。

Historically, many attacks exploited the way the command shell handled the IFS environment variable, but most of today's shells (including GNU bash) have been modified to make IFS harder to exploit.

youdao

You can only use the state variables independent of history.

你只能使用不依赖于历史的,状态变量。

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