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Accepted
Jack Chen
Asked: 2019-06-11 06:19:39 +0800 CST

关于调试陷阱的问题

  • 772

我有一个脚本如下：

function dbgtrap {
echo "badvar is $badvar" 
}

badvar=0

function some_func {
    badvar=1
    badvar=2
    badvar=3
}

set -o functrace

trap dbgtrap DEBUG
    some_func
trap - DEBUG    # turn off the DEBUG trap

获取脚本后，我得到了输出：

badvar is 0
badvar is 0
badvar is 0
badvar is 1
badvar is 2
badvar is 3

我期待的东西像：

badvar is 0
badvar is 1
badvar is 2
badvar is 3

输出的前两行来自哪里？

shell-script debugging

1 个回答

  1. Best Answer

    一旦设置了每个命令行，就会调用陷阱。如使用下面的 TRACE 输出所示：

    + badvar=0
+ set -o functrace
+ trap dbgtrap DEBUG
++ dbgtrap
++ echo 'badvar is 0'
badvar is 0
+ some_func
++ dbgtrap
++ echo 'badvar is 0'
badvar is 0
++ dbgtrap
++ echo 'badvar is 0'
badvar is 0
+ badvar=1
++ dbgtrap
++ echo 'badvar is 1'
badvar is 1
+ badvar=2
++ dbgtrap
++ echo 'badvar is 2'
badvar is 2
+ badvar=3
++ dbgtrap
++ echo 'badvar is 3'
badvar is 3
+ trap - DEBUG

    IIRC shell 在处理结束时调用陷阱，因此在 badvar 值的函数调用输出之前有 3 行输出。

    • 2

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