Bash assign variable from a command output

How do I assign the output of a shell command to a shell variable under Unix like operating system? For example, I want to store the date command output to a variable called $now. 

How do you do that?

var=$(/path/to/command arg1 arg2)

The content of test.sh

#!/bin/bash

PROD=$(ls -al)

echo "${PROD}"

the output

~$ bash test.sh |grep xen

drwxrwxr-x   3 user group       4096 Mar  7  2017 test_xen

drwxrwxr-x   3 user group       4096 Mar  7  2017 test_xen_4.7