Using IFS with echo [duplicate]

问题

This question already has answers here:

How can I convert an array to a comma separated list in Bash? (5 answers)

Why can't I set IFS for one call of printf (2 answers)

Closed 5 months ago.

Why does this:

arr=(1 2 4 8 16)
IFS=,
echo "${arr[*]}"

print out 1,2,4,8,16 (which is what I want) but this doesn't:

arr=(1 2 4 8 16)
IFS=, echo "${arr[*]}"

?

I'd like to have a temporary IFS without having to set it then reset/unset it.

来源：https://stackoverflow.com/questions/57627024/using-ifs-with-echo