This will replace all occurrences of match_pattern in the file

:g/match_pattern/s//replace_string/g

ex: you want to change all occurrences of an allow rule in your vhost file and comment it out

Allow from 192.168.0.1 to #Allow from 192.168.0.1

:g/Allow from/s//#Allow from/g

This command will find and replace the string that matches the condition.

alternatively, you can use ‘ : ‘ instead of ‘ / ‘ to make path (/) slashes easier to manage (no escape (\) character needed)

:g:match_pattern:s::replace_string:g