evaluating variable that comes in an array in shell script

Question

I am trying to read Xcode build settings via shell script, i.e. if there is a build setting called PRODUCT_NAME, I read its value by writing echo ${PRODUCT_NAME} in shell script.

Now, I get this PRODUCT_NAME in an array, lets call myArr having just one element PRODUCT_NAME. I loop over that array as

for i in "${myarr[@]}"
do
:
    echo $i 
done

echo $i would simply output PRODUCT_NAME. However, I want to write something that would evaluate ${PRODUCT_NAME} and give me results.

I have also tried eval echo $i but that also outputs PRODUCT_NAME only

Is the array positional (numeric indexes) or associative (text keys)? — cdarke, Nov 06 '16 at 08:36

score -1 · Accepted Answer · edited May 23 '17 at 10:30

-1

Solved it by using

echo "${!i}"

The second line gives the output as desired. I have taken this answer from here: How to get a variable value if variable name is stored as string?

edited May 23 '17 at 10:30

Community

1
1

answered Nov 06 '16 at 01:51

prabodhprakash

3,825
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3

You don't need the `eval`, or even a temporary variable. Just use `echo ${!myarr[0]}`. – chepner Nov 06 '16 at 02:01
1

In fact, `echo "${!i}"` is all you need inside the loop. – Nov 06 '16 at 05:30

score -1 · Answer 2 · answered Nov 08 '16 at 10:10

As I interpret your problem, You hold the array of variables, and while traversing, you want to use the actual values of the variables.

I tried the below code which is almost similar to which you have written and seems working.

#!/bin/bash

PRODUCT_NAME="Calendar"
PROCUCT_VER="2.3"
PROCUCT_OWNER="Sam"

PRODUCT_DETAILS=( $PRODUCT_NAME $PROCUCT_VER $PROCUCT_OWNER )

for PRODUCT_PROPERTY in "${PRODUCT_DETAILS[@]}"
do
    echo "PRODUCT_PROPERTY: $PRODUCT_PROPERTY"
done

Output:

PRODUCT_PROPERTY: Calendar

PRODUCT_PROPERTY: 2.3

PRODUCT_PROPERTY: Sam

evaluating variable that comes in an array in shell script

2 Answers2