Take the 2-minute tour ×
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.. It's 100% free, no registration required.

I have two arrays:

arrayA=(1 2 3)
arrayB=(a b c)

and I want to print out one of them using a command line argument, i.e., without any if else.

I tried a few variations on the syntax with no success. I am wanting to do something like this:


echo ${array${ARG}[@]}

but I get a "bad substitution" error. How can I achieve this?

share|improve this question

3 Answers 3

up vote 6 down vote accepted

Try doing this :

$ arrayA=(1 2 3)
$ x=A
$ var=array$x[@]
$ echo ${!var}
1 2 3


  • from man bash (parameter expansion) :
           The value of parameter is substituted.
 The braces are required when parameter is a positional parameter with
  more than one

digit, or when parameter is followed by a character which is not to be interpreted as part of its name.
* If the first character of parameter is an exclamation point (!), a level of variable indirection is introduced. Bash uses the value of the variable formed from the rest of parameter as the name of the variable; this variable is then expanded and that value is used in the rest of the substitution, rather than the value of parameter itself. This is known as indirect expansion. * The exceptions to this are the expansions of ${!prefix*} and ${!name[@]} described below. The exclamation point must immediately follow the left brace in order to introduce indirection.

share|improve this answer
What exactly is the ! doing in front of the var variable? How does that work, it seemed to be history substitution on googling, but I couldn't see how that worked here. –  Aaron Jan 7 '13 at 22:44
See my edited post –  StardustOne Jan 7 '13 at 22:53

no way :(

if your arrays are that simple, then use associative arrays

    declare -A array
    array[A]="1 2 3"
    array[B]="a b c"

unfortunately, if your arrays are more complicated ( for example array=( "a b" c ) ), that wouldn't work. Then, you need to think harder about another way to reach your goal.

share|improve this answer
What is the reason for the downvote? The associative array provides a nice way of grouping everything, assuming that my elements will all contain no space. –  Aaron Jan 7 '13 at 23:45
@Aaron Assuming your elements don't contain spaces, that is a reasonable design. @watael I guess beginning the answer with “no way” when the primary focus of your question is clearly possible wasn't a good idea. –  Gilles Jan 8 '13 at 0:12

Use eval

arrayA=(1 2 3)
eval echo \${$ARG[@]} # equivalent to eval echo \${arrayA[@]}
                      # note that we escape the first '$' to prevent from 
                      # its parameter expansion before passing it to echo
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.