Windows Ctrl+Alt+Del equivalent in Linux

Ctrl+Alt+Del in KDE Plasma => shutdown

Ctrl+Alt+F2 // 

login and killall appname

Ctrl+Alt+F1 // return to normal mode

Ctrl+Alt+Backspace => kill X (graphical interface)

sudo systemctl restart display-manager // restart desktop (graphical interface)

sudo /etc/init.d/gdm restart // restart X (graphical interface)

sudo shutdown -r now // reboot

sudo reboot

top // display processes

pstree // display processes tree

ps aux | grep proccessname

Ctrl+C // cancel === exit