To kill a process use kill process-id, where <process-id> is as shown by the ps
command, or kill %n, where n is the job number as reported by the jobs command. If
you feel lazy about finding the process id (laziness can be a good trait for a programmer!),
then you can use the killall command, which kills by the name of the process. For example,
you can use killall wordfreq, which kills all processes that have the string wordfreq
as a part of their name.
If a process has gone amok and does not respond to the kill command, you can give the
-9 option (which is the same as the SIGKILL signal, a signal that will almost surely
kill the process).
killall -9 wordfreq
