As the owner of the OHS Oracle Home, in the ohs/bin subdirectory of that Oracle Home...
./httpd -version
As the owner of the OHS Oracle Home...
opmnctl status
To start everything under OPMN control...
opmnctl startall
To start just the Oracle HTTP Server...
opmnctl startproc ias-component=HTTP_Server
opmnctl restartproc ias-component=HTTP_Server
To stop everything under OPMN control...
opmnctl stopall
To start just the Oracle HTTP Server...
opmnctl stopproc ias-component=HTTP_Server