Ubuntu – Can console be suspended and ask for a password on wakeup


Although I suspect that this is not currently possible, I would just like to ask because it would be something very useful in my opinion. Because when I close my lid and I am in the GUI my computer suspends and then requires a password to be unlocked. However if I do the same in console, there is no suspend and it doesn't ask me for a password to log back in again.

Now this can be a potential security risk so I was wondering if there was a way to pause everything running through console when the lid is closed, and so that when the machine awakes, you have to enter your password back into the console window so that it 'unlocks' your session? I am running Ubuntu GNOME 15.04. When I say the console, I mean the TTYs.

I have had a look at TTY[1-6]: Lock screen after delay (like a screensaver), however I do not feel that it fully answers my question, especially about pausing anything running so that it can continue upon resume.

I am running Ubuntu GNOME 15.10 with GNOME 3.18.

Best Answer

The other question that muru has linked in the comments ( TTY[1-6]: Lock screen after delay (like a screensaver) ) offers us the tool to locking the tty , vlock. At the simplest level , you can combine vlock -a with pm-suspend into a .bashrc function or a script. Here's mine:

$ cat lockTTY.sh 
(sleep 3; sudo pm-suspend) &
vlock -a 

What is happening here ? Basically we're launching pm-suspend with delay in subshell , in background. Meanwhile we use vlock -a to lock all the ttys. After 3 seconds, the laptop suspends.

The catch here however is the sudo pm-suspend part. You have to prevent sudo from asking you password for pm-suspend. In order to do that, we add the following line at the end of /etc/sudosers file

$USERNAME ALL = NOPASSWD: /usr/sbin/pm-suspend

Of course , replace $USERNAME with your actual username. You might call sudo visudo to open that file with your default text editor set in /etc/alternatives/editor , just to be safe, but any editor called with proper permissions will do.

What does this script allows us to do ? Suspend and lock with processes still running. vlock -a has big advantage in preventing switching to other consoles, so it's not just one console being locked, but all of them - you cannot just switch to another tty if one is locked.

You could also suspend first and lock second, i.e. call pm-suspend first and vlock -a second. But that means upon resume there is possibility someome may see your screen for a fraction of a second before vlock kicks in.

What would be the simple and dirty solution in case you don't trust vlock and don't want to install it ? Create a script /etc/pm/sleep.d/10_lockTTY with the following contents:


case "${1}" in
     for NUM in $(seq 1 6); do service tty$NUM restart; done         

This will reset all ttys upon return from suspend, but mind - any processes you had there will be killed.