Apache's init script needs a small addition to allow it to perform graceful
restarts--graceful restarts do zero-downtime updates of loaded modules and
configuration file alterations.  This is very handy for people using Apache
on mission-critical servers.

The URL I listed explains exactly what how graceful restarts work.

Here's what I added to the /etc/rc.d/init.d/httpd init script:

  hotstart)
        echo -n "Hot starting httpd: "
        killproc httpd -USR1
        echo
        ;;

"graceful" might be a better name for the target than "hotstart".  Also, it
would make a lot of sense to store the killproc return value and exit from
the init script with that return value.  That would turn the above into:

  graceful)
        echo -n "Gracefully restarting httpd: "
        killproc httpd -USR1
        RV=$?
        echo
        exit $RV
        ;;

And the default line ("Usage: $0 {.....}") should probably mention the
graceful/hotstart option.

E-mail me if you have any questions: SumnerH at fool.com