How to kill multiple processes

You can use pkill:

pkill httpd

You may also want to use process substitution(although this isn't as clear):

kill $(pgrep command)

And you may want to use xargs:

pgrep command | xargs kill

You can use killall as well, e.g.

killall firefox

to send SIGTERM to all firefox processes.

Yes, you can use a bash feature and looping over the output.

$ for proc in $(pgrep <process command>); do kill $proc; done