Modify global variable array through a bash function, passing the function the name of the variable as a string

Question

Dear I need something to help me in this. I'm trying to modify a global array through a function , using an auxiliary variable called "array". I would like to modify the global array "config " using a function that takes a string with the name of the variable " config".

I'm trying the following but I have not gotten results .

declare -A config

function testABC {
    array=${1}[@]
    array["key"]="value1"
    array["key2"]="value2"
}

testABC "config"
echo ${config["key"]}
echo ${config["key2"]}

#desired output:
#value1
#value2

My version of bash is 4.2.45

regards.

chepner · Accepted Answer · 2015-08-01 13:42:04Z

2

Use printf -v to set the value. This avoids an unsafe use of eval, as printf can only print text into a named variable, nothing more.

testABC () {
    printf -v "$1[key]" '%s' value1
    printf -v "$1[key2]" '%s' value2
}

Be sure to read http://mywiki.wooledge.org/BashFAQ/006 (from which this answer is taken) for a good understanding of the drawbacks of the various approaches. Shell languages simply aren't a good fit for this type of programming.

answered Aug 1, 2015 at 13:42

chepner

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chepner · Accepted Answer · 2015-08-01 13:35:41Z

1

You almost got it right, something like this should work:

function testABC {
  array="$1"
  # Don't proceed unless the argument is a valid identifier
  valid_id="^[[:alpha:]_][[:word:]]+$"
  [[ $array =~ $valid_id ]] || return

  eval "$array"["key"]="value1"
  eval "$array"["key2"]="value2"
}

We store the argument passed to the function in array variable. After that we construct line that assigns values to keys and use eval. eval replaces $array with "config" and executes the whole line, assigning the values properly.

edited Aug 1, 2015 at 13:35

chepner

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answered Aug 1, 2015 at 6:49

tvm

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1 Comment

chepner Over a year ago

Don't use eval without knowing that $1 is just the name of an array. You're allowing testABC to execute arbitrary code passed as an argument.

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