[Help-bash] How to replace a number of substrings simultaneously?

[Peng Yu]

Hi,

I'd like to replace a number of substrings in a string simultaneously in bash.

For example, replace "s1" by $s1, replace "s2" by $s2,...

Something like this will not work robustly, because if $s1 is "s2",
then there will be two $s2 in the result.

x=${x//s1/$s1}
x=${x//s2/$s2}

It can be relatively easy to achieve this in other languages. But it
is not clear what might be the most succinct way to achieve it in
bash.

Does anybody know? Thanks.

-- 
Regards,
Peng