How to kill all running applications using terminal command.
we usually kill by command top and got the code of the application.

ps aux - to show list of running processes
ps aux | grep jetty - get list of all processes containing jetty and colour highlight them
kill 12345 - terminate/kill process with given ID

For Redhat Linux Insert CDROM is mounted in /mnt/cdrom,

rpm --import /mnt/cdrom/RPM-GPG-KEY
rpm -qa gpg-pubkey*
rpm -qi gpg-pubkey-db42a60e-37ea5438
rpm -K /tmp/updates/*.rpm

Then type the following as root into a shell prompt:

ps -aux | grep imap

kill -9 <PID>

killall imapd


Follow peter_budo not searchec. searchec having you regenerate the GPG key makes no sense however the ps aux is correct and killall is good for killing a specific application (example: killall html ).

If you want to log everyone out and kill all their apps ( I am a teacher. I have delusions of omnipotence... ;-) ), use /etc/init.d/gdm restart or stop.

That stops all the login sessions to the GUI which accomplishes a lot. I sometimes set that up in a crontab to dismiss class at a certain time... You can also use pkill -u someuser or pkill -f somecommand (watch out. That kills fred's somecommand and Bill's somecommand but it allows to kill all instances of something like a web browser.)

If you want to kill an application for example firefox:
# pidof firefox
# kill <pid>
or by simply typing
# killall firefox