Sometimes we need to restart the web server apache in order to reload the new settings, for example, you added some new host config. But we don’t want that the current requests be lost, and we then don’t want that this reload of settings cause problems for the users.
Debian/Ubuntu/Mint:
Reload the settings using the command service
$ sudo service apache2 reload
RedHat/Centos/Fedora:
Reload the settings using the command service
$ sudo service httpd reload
For ALL distributions:
Reload the settings using the command apachectl
$ sudo apachectl -k graceful