在“陷阱退出"窗口中获取shell脚本的退出代码. [英] Get the exitcode of the shell script in a "trap EXIT"

问题描述

我想在我的Bash脚本中执行清理操作，如下所示:

I want to have a cleanup action in my Bash scripts, like this:

#! /bin/bash
set -eu
trap 'echo "E: failed with exitcode $?" 1>&2' ERR

true
false

使用 $?是自然的选择，但事实并非如此.它始终包含 0 .我有什么办法可以监视" ERR 陷阱中的退出代码?

Using $? came to mind as a natural choice, but this isn't the case. It always contains 0. Is there any way that I can "spy" on the exitcode in the ERR trap?

[更新:] 我不知道以前测试过什么.这段代码的工作原理很吸引人，因此我将其作为一个小巧的示例留在这里.

[Update:] I have no idea what I had tested before. This code works like a charm, so I'm leaving it here as a small and good example.

推荐答案

您的(可能是简化的)示例没有出现您提到的问题:

Your (probably simplified) example doesn't exhibit the problem you've mentioned:

+ set -eu
+ trap 'echo "E: failed with exitcode $?" 1>&2' ERR
+ true
+ false
++ echo 'E: failed with exitcode 1'
E: failed with exitcode 1

有可能在&& 或 || 中执行返回 ERR 的命令，或者要遵守下面的代码段.引用手册:

Chances are that the command returning ERR is executed in a && or ||, or subject to other conditions mentioned in the snippet below. Quoting from the manual:

如果 sigspec 是 ERR ，则只要简单该命令的退出状态为非零，但必须遵守以下规定使适应.如果失败的命令是一部分，则不会执行 ERR 陷阱在 until 或 while 关键字之后的命令列表中，在 if 或 elif 保留字之后的测试部分，在&& 或 || 列表中执行的命令，或者该命令的返回状态正在使用！反转.这些是相同的条件， errexit 选项.

If a sigspec is ERR, the command arg is executed whenever a simple command has a non-zero exit status, subject to the following conditions. The ERR trap is not executed if the failed command is part of the command list immediately following an until or while keyword, part of the test following the if or elif reserved words, part of a command executed in a && or || list, or if the command’s return status is being inverted using !. These are the same conditions obeyed by the errexit option.

例如，如果您具有以下内容:

So if you have, for example, the following:

#! /bin/bash
set -eu
trap 'echo "E: failed with exitcode $?" 1>&2' ERR

false && true

执行该操作不会导致失败被困:

Executed it wouldn't cause the failure to be trapped:

+ set -eu
+ trap 'echo "E: failed with exitcode $?" 1>&2' ERR
+ false

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