命令中插入了重复的 Perl 表达式

Question

这有道理吗？我需要“编辑”插槽以将其转换为 GPU 板号，但如果我使用多个输入列表，它会将多个 Perl 结果副本放入并行命令中。

是否有一种正确的方法可以在保留“:::”语法的同时仅获取一个 perl 替换实例？

GNU parallel 20230822
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bash-4.2$ parallel --dry-run --jobs 3 echo {= '$_=slot()-1' =} ::: 1 2 3 4
echo 0
echo 1
echo 2
echo 0
bash-4.2$ parallel --dry-run --jobs 3 echo {= '$_=slot()-1' =} ::: 1 2 3 4 ::: a b c
echo 0 0
echo 1 1
echo 2 2
echo 0 0
echo 1 1
echo 2 2
echo 0 0
echo 1 1
echo 2 2
echo 0 0
echo 1 1
echo 2 2
bash-4.2$ parallel --dry-run --jobs 3 echo {= '$_=slot()-1' =} ::: 1 2 3 4 ::: a b c ::: 1
echo 0 0 0
echo 1 1 1
echo 2 2 2
echo 1 1 1
echo 0 0 0
echo 2 2 2
echo 1 1 1
echo 0 0 0
echo 2 2 2
echo 1 1 1
echo 0 0 0
echo 2 2 2

Answer 1

我偶然发现了一种获得我期望的行为的方法：

bash-4.2$ parallel --dry-run --jobs 3 echo {=1 '$_=slot()-1' =} ::: 1 2 3 4 ::: a b c
echo 1
echo 0
echo 2
echo 1
echo 0
echo 2
echo 1
echo 0
echo 2
echo 1
echo 0
echo 2

不太清楚为什么，但它确实有效。