以特殊字符作为元素的回声组合(echo combinations with special character as elements)

 我有一个小脚本，利用回声能力生成元素组合。 那是代码片段， 
 
set={1,2,3,4}
group=3
for ((i=0; i<$group; i++));
do
  repetition=$set$repetition
done

bash -c "echo "$repetition""
 
 这工作正常，问题来自我希望集合由一些特殊字符组成，如逗号，parenthesys等。我尝试过scape但它似乎不起作用，类似于 
 
set={(,),\,,=}
 
 关于如何实现它的任何线索？ 

I've a small script which takes advantage of the echo ability to generate combinations of elements. That's the piece of code,
 
set={1,2,3,4}
group=3
for ((i=0; i<$group; i++));
do
  repetition=$set$repetition
done

bash -c "echo "$repetition""
 
That works fine, the problem comes when I want the set to consist of some special characters, like commas, parenthesys, etc. I've tried with scapes but it doesn't seem to work, something like
 
set={(,),\,,=}
 
Any clue about how to achieve it?

原文：https://stackoverflow.com/questions/26177816