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?

bobah · Accepted Answer · 2012-04-20 11:13:48Z

3

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

answered Apr 20, 2012 at 11:13

bobah

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4 Comments

great, good to know dereferences work with vars ;) I only knew that syntax in bash arrays.

why don't you do it like this?: a=test; b=$a; echo $b

@RaphaelRoth - because what you suggest is not indirection

A more portable alternative (but also quite dangerous if not used carefully) is eval echo \$$b.