Is there any way that I can lock the screen CLI-style? I'm trying to target as many desktop managers as possible (mostly LightDM, but GDM, KDM, SLiM, XScreensaver, etc. would be great too), but I can only dig things up for GDM and XScreensaver.

For GDM, it would be:

gnome-screensaver-command -l

For XScreensaver:

xscreensaver-command -lock

Is there a similar command for KDM and LightDM?

  • Can you start the screen saver and ssh in and ps and see what screen saver is running and deduce from there what command to run? (how I found the gnome-screensaver-command) – polynomial Sep 30 '11 at 4:35
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    man lightdm doesn't look too promising... moleberry.com/man/l/lightdm.1.html – jasonwryan Sep 30 '11 at 5:41
  • Perhaps you can try to control them via d-bus (using dbus-send to send the appropriate lock message). – andcoz Sep 30 '11 at 9:24
  • @andcoz: I saw a few dbus-send things while Googling, but sadly none of them worked. I even looked at the LightDM API reference for a solution, but even that doesn't have anything. Heck, I even tried to look at the source of Ubuntu's user switching panel (sorry, can't read like 1,000,000 of C). I might try emailing the dev list for help... – Blender Sep 30 '11 at 15:48
  • @polynomial: That seems like a good solution (maybe post it as an answer?). I don't have a second computer to SSH with, but I can try and print the process list every second or so to deduce what is happening. – Blender Sep 30 '11 at 15:51

I Googled/emailed around a bit and got these two commands.

To lock the screen:


To activate user switching:


For Lightdm, this file resides in a strange spot (at least on Arch Linux):


I merged these two into XFCE's logout button dialog, in case anyone's interested, so the patch is available here: https://aur.archlinux.org/packages.php?ID=52816

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  • Xflock4 must have gnome-screensaver – Prvt_Yadav Apr 28 '18 at 19:29

You can lock all screen savers on X by using xdg-screensaver

xdg-screensaver lock

It'll take care of the gory details.

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There are several DM-independent, simple solutions like alock, slock or xtrlock (manpage). Note that they might not even display any input window prompting for password - you just enter the password while the screen is blank and press Enter (that's the case of slock at least).

If you want the locker to be able to display a screensaver and show a custom prompt on un-locking, try xlock provided with xlockmore package (see this info and the manpage).

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  • I'm not looking for a lock screen (I have my own, plock, for that :P). I'm looking for a way to trigger the lockscreen (whatever it is). – Blender Sep 30 '11 at 15:47
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    Then xautolock (which is a part of xlockmore) provides this functionality - have a look at the last two links I posted and the xautolock manpage. – rozcietrzewiacz Oct 2 '11 at 18:07

For a environment agnostic lock app, there is i3lock which also lets you set the lockscreen background.

For LightDM you can run light-locker as a background process in your session. It will lock your session as soon as the screensaver starts/system resumes from suspend.

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This is not pretty, but working solution for unlock kde or lightdm session from screensaver via cli (command line):

qdbus | grep kscreenlocker_greet | xargs -I {} qdbus {} /MainApplication quit
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