Locking your session with vlock
If you need to lock your account without log out, you can use ‘vlock’, a very simple-to-use utility to lock virtual consoles.
vlock. Then, to lock your current virtual console, just type
This TTY is now locked. Please press [ENTER] to unlock.
To unlock you will need to type your password. You can lock all your consoles with
vlock -a (you won’t be able to change console with Ctrl + Alt + F buttons, but this won’t work on SSH sessions or terminal emulators):
The entire console display is now completely locked. You will not be able to switch to another virtual console. Please press [ENTER] to unlock.