set output into variable from grep from input variable

whats wrong with this bash script: acme2=$(dig txt @$1 _acme-challenge.$1.de) acme3=$(echo $acme2 | grep "^_acme") acme2 has the whole output, but acme3 is always empty I searched several solutions, and tried other possibilities, but nothing works... acme3=echo $acme2|grep acme acme3=$($acme2|grep "^_acme") acme3=$(grep "acme" $acme2) acme3=$(echo "$acme2" | grep "^_acme")