bash expanding value of a variable to use in another variable

Question

I hope the question makes sense, I would like to do something like:

a=test
b=a
echo ${$b} # should echo test

Basically I'd like $b to expand to the value a and have bash echo out the value of variable $a (since ${a} is test).

What syntax should I use?

score 3 · Accepted Answer · answered Apr 20 '12 at 11:13

3

a=test
b=a
echo ${!b} # does echo test

answered Apr 20 '12 at 11:13

bobah

great, good to know dereferences work with vars ;) I only knew that syntax in bash arrays. – c00kiemon5ter Apr 20 '12 at 11:14
why don't you do it like this?: a=test; b=$a; echo $b – Raphael Roth Apr 20 '12 at 13:28
@RaphaelRoth - because what you suggest is not indirection – bobah Apr 20 '12 at 14:34
A more portable alternative (but also quite dangerous if not used carefully) is `eval echo \$$b`. – Idelic Apr 20 '12 at 16:54

1 Answers1