語境

在設定基本單元測驗系統時，我遇到了一個奇怪的問題。我的目標是確保所有單獨的測驗腳本：

運行set -e以檢測錯誤，而無需在每個檔案中明確設定；
立即知道要測驗的功能（存盤在另一個檔案中），而無需在每個測驗檔案中顯式獲取這些功能。

觀察

假設這是一個名為to-be-sourced.sh. 我們希望能夠知道其中的命令是否失敗：

# Failing command!
false

# Last command is OK:
true

這是一個虛擬測驗運行器，它必須運行測驗檔案：

#! /usr/bin/env bash

if (
    set -e
    . to-be-sourced.sh
)
then
    echo 'Via set: =0'
else
    echo 'Via set: ≠0'
fi

這會產生Via set: =0，這意味著跑步者很開心。但它不應該！我的假設是：

set -e is not propagated within . sourcing, and as explained in the help for . and source, the exit status is the one of the last command.

But then I came up with a workaround that works, but also relies on .:

if bash -ec '. "$0"' to-be-sourced.sh
then
    echo 'Via bash: =0'
else
    echo 'Via bash: ≠0'
fi

This yields ≠0 whenever a command in the test file fails, regardless of whether that command was the last one of the test file. As a bonus, I can toss any number of . a/library/file.sh within the -c command, so each test file can use all of my functions out of the box. I should therefore be happy, but:

Why does this work, considering that the -c command also relies on . to load the test file (and I thought bash’s -e was equivalent to set’s -e)?

I also thought about using bash’s --init-file, but it appeared to be skipped when a script is passed as a parameter. And anyway my question is not so much about what I was trying to achieve, but rather about the observed difference of behavior.

Edit

Sounds like if is tempering with the way set -e is handled.

This halts execution, indicating failure:

. to-be-sourced.sh

… while this goes into the then (not the else), indicating success:

if . to-be-sourced.sh
then
    echo =0
else
    echo ≠0
fi

uj5u.com熱心網友回復：

（這可能并不完全正確，但我認為它捕捉到了發生的事情。）

在您的第一個示例中，在陳述句范圍內的詞法set -e命令中設定選項，因此即使設定了它，它也會被忽略。（您可以通過運行inside來確認它是否已設定。同樣請注意，它本身具有 0 退出狀態，您可以通過替換陳述句來確認它；不是它失敗而是忽略了失敗。）ifecho $-to-be-sourced.sh.trueecho

在您的第二個示例中，在新行程-e中設定選項，該行程對陳述句一無所知，因此不會被忽略。errexitif

轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/451504.html

標籤：bash

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“set-e source”和“bash-ec source”之間的行為差??異

語境

觀察

Edit