^C

   Control-C will send an interrupt to the current program.  Most programs will
   immediately exit when this signal is received, some will ignore it, or will
   delay before acting.  Generally, this is the best way to stop a program that
   needs to be stopped.

^D

   Control-D sends the End-Of-Text (EOT) signal to a program.  Many programs
   dealing with keyboard input will terminate when this signal is used.

^Z

   Control-Z instructs the operating system to immediately halt execution
   of a program.  A halted program will not terminate, or resume, but will
   sit idle until dealt with.  If you attempt to logout with a stopped
   program, you may be warned of a stopped job; attempting to logout again
   may force the job to terminate.

fg

   ForeGround is the easiest way to resume a program.  Uses are:

         fg                  Restart most recently halted job
         fg %1               Restart job #1
         fg %3               Restart job #3  (see 'jobs' command)

bg

   BackGround will resume a program at a lower priority, and allows
   the user to do other things at the same time (i.e. it does not
   interact with the user, so they can go run other programs).
   A program in the background will run until finished, or it will halt
   if it expects input.  A program in the background can be brought to
   the foreground, even when running, with the 'fg' command.  Uses are
   the same as for fg.

kill

    Kill often causes a program to immediately terminate.  Most (95%) programs
    will die gracefully, while some may be stubborn.  It sends an interrupt
    (^C) by default, but can send other signals as well.

        kill %1            Terminate job #1
        kill %3            Terminate job #3
        kill -9 <PID>      Will kill even the most stubborn program.  Note
                           that the Process ID number (PID) can be found
                           with 'ps'.  Note that using this command to kill
                           your login shell will immediately log you out.

jobs

    Will show a listing of all jobs, running or halted, such as:

          [1] + Running       mail
          [2] - Stopped       telnet

    Note that the number in brackets [] is the index number that can be
    used with 'fg', 'bg', and 'kill', as in 'fg %1'

&

    Used to start a program in the background.  For instance:

          finger &              Run 'finger' in the background
          who &                 Run 'who' in the background

Note that these job control commands are very helpful in doing
several things at once, because they allow programs to run simultaneously
(one of the best features of UNIX).