On this text
hardware mac 33:33:333:33:33 hardware mac 33:13:333:33:33 hardware mac 33:23:333:23:34 hardware mac 33:033:133:33:35 ...
I want to replace all lines starting with hardware mac with
hardware mac 00:00:00:00:00:00
I have tried
sed s/^hardware mac/hardware mac 00:00:00:00:00:00/gc
and give error
also the classic vim command
%s:/^hardware mac/hardware mac 00:00:00:00:00:00/gc
But change only the string hardware mac leaving the numbers untouched. How to replace string beginning with hardware mac with my string?