#!/bin/bash
variable1=$(sed -n "/^variable_1 = \"\(.\+\)\"$/s//\1/p" variables)
variable2=$(sed -n "/^variable_2 = \"\(.\+\)\"$/s//\1/p" variables)
echo "$variable1,$variable2"
sed -i "/variable_2\ =\ \"/ s/=.*/=\ \"$variable1\"/" variables
sed -i "/variable_1\ =\ \"/ s/=.*/=\ \"$variable2\"/" variables