bash how to get async command output to variable

i want to know how can we get command output to variable in bash

here is my code

#!/bin/bash
opt="svcrack -v -u100 -r1-9999 -z3 10.0.0.1"
opt2="$($opt)"

echo "myout output $opt2"

output

myout output 

not working inside function 🙁

function zwork(){

opt=$(svcrack -v -u100 -r1-9999 -z3 10.0.0.1 2>&1)

echo "myout output $opt"
}

out=$(zwork)

Answer

Please try redirecting stderr to stdout like:

#!/bin/bash
opt=$(svcrack -v -u100 -r1-9999 -z3 10.0.0.1 2>&1)

echo "myout output $opt"

Here you can read more about command substition.