懒惰的评价猛砸 [英] Lazy Evaluation in Bash

问题描述

是否有这样做懒的评价比下面的更优雅的方式：

Is there more elegant way of doing lazy evaluation than the following:

pattern='$x and $y'
x=1
y=2
eval "echo $pattern"

结果：

1 and 2

它的工作原理，但评估回声......只是觉得草率，并可能以某种方式不安全。有没有更好的办法在Bash中做到这一点？

It works but eval "echo ..." just feels sloppy and may be insecure in some way. Is there a better way to do this in Bash?

推荐答案

您使用的评估的是正确的，实际上它在shell编程一个pretty常见的模式。 评估的可能是一个安全隐患，确实，但只有当脚本获得权限或数据来自不受信任的来源。我想这不是你的情况吧？

Your use of eval is correct, in fact it's a pretty common pattern in shell programming. eval may be a security risk, indeed, but only if the script gains privileges or the data comes from an untrusted source. I imagine that's not your case, right?

顺便说一句，你也可以这样写：

By the way, you can also write this:

pattern='$x and $y'
x=1
y=2
eval "result=\"$pattern\""

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