Bash - variable variables

BashVariables

Bash Problem Overview

I have the variable $foo="something" and would like to use:

bar="foo"; echo $($bar)

to get "something" echoed.

Bash Solutions

Solution 1 - Bash

In bash, you can use ${!variable} to use variable variables.

foo="something"
bar="foo"
echo "${!bar}"

# something

Solution 2 - Bash

eval echo \"\$$bar\" would do it.

Solution 3 - Bash

The accepted answer is great. However, @Edison asked how to do the same for arrays. The trick is that you want your variable holding the "[@]", so that the array is expanded with the "!". Check out this function to dump variables:

$ function dump_variables() {
    for var in "$@"; do
        echo "$var=${!var}"
    done
}
$ STRING="Hello World"
$ ARRAY=("ab" "cd")
$ dump_variables STRING ARRAY ARRAY[@]

This outputs:

STRING=Hello World
ARRAY=ab
ARRAY[@]=ab cd

When given as just ARRAY, the first element is shown as that's what's expanded by the !. By giving the ARRAY[@] format, you get the array and all its values expanded.

Solution 4 - Bash

To make it more clear how to do it with arrays:

arr=( 'a' 'b' 'c' )
# construct a var assigning the string representation 
# of the variable (array) as its value:
var=arr[@]         
echo "${!var}"
Categories
Recommended Bash Solutions
Recommended Variables Solutions

Previous Solution:

ASP.Net MVC and state - how to keep state between requests

asp.net MvcActionViewmodelState

Next Solution:

How to trigger NSTimer right away?

IosNstimer

Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
Questionuser1165454View Question on Stackoverflow
Solution 1 - BashdAm2KView Answer on Stackoverflow
Solution 2 - BashMatt KView Answer on Stackoverflow
Solution 3 - BashbishopView Answer on Stackoverflow
Solution 4 - BashJahidView Answer on Stackoverflow