There are stopped jobs
Sometimes when you try to logout with the logout command,
you'll get the message There are stopped jobs. This means
that you have left some suspended jobs hanging around, and you should
finish them off before you log out. Type jobs as above to
get a list of what jobs are stopped; then, you can bring them to the
foreground one at a time (with `fg %1' and so on) and exit
each normally.
You can also type
% kill %3
to kill job number 3, which will cause it to exit prematurely.
If you get stuck or are in a hurry you can use the logout
command twice in a row and you'll be able to log out in spite of your
stopped jobs. The jobs will be killed automatically by the shell.
You really should clean them up yourself though.
If you have background jobs running (as opposed to stopped jobs) they
will continue to run after you log out.