arping后$?的问题

sparkoo

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aaa@1[bbb]$ sudo arping -A -q -c 1 192.168.1.10
aaa@1[bbb]$ echo $?
1
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aaa@1[bbb]$ sudo sh -c "arping -A -q -c 1 192.168.1.10
>echo $?"
0
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为什么两次$?的值是不一样的啊?