Bash: expand parameters from variable. How?

问题

I want to expand tar parameter --exclude thru variable like:

set -x verbose
EXC=AAA,BBB
echo --exclude={$EXC} > /dev/null

Output: echo '--exclude={AAA,BBB}'

But I expect: echo --exclude=AAA --exclude=BBB

I tried different invocations, but nothing.. Whats wrong?

回答1:

You need to use eval to parse the line after substituting the variable.

eval "echo --exclude={$EXC}"

来源：https://stackoverflow.com/questions/17673337/bash-expand-parameters-from-variable-how