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I am using Ubuntu 12.04. Is there any way to lock the screen or session from a terminal command or script?

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11 Answers 11

93

Simple:

gnome-screensaver-command -l

The following can also work, if the screensaver is set to lock when activate (see screensaver settings), since the command activates the screensaver:

gnome-screensaver-command -a

You can add an alias to the command by editing the file .bashrc (or .bash_aliases) in your home directory:

gedit $HOME/.bashrc

and adding the following line:

alias lock='gnome-screensaver-command -l'

Then from terminal:

source .profile

This will activate the alias. From now on, the alias lock in a terminal will have the effect of locking the screen.

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  • Sorry, I had to modify your changes. (i) no need to use sudo (ii) better .profile than .bashrc, since .bashrc gets called every time you create a new shell and (iii) alias works only when called from shell. – January Sep 21 '12 at 14:18
  • ok now its looking good , you like the idea ? – rɑːdʒɑ Sep 21 '12 at 14:50
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    sure. I usually lock with a single keypress, though, makes it quicker when leaving the office for a coffee. – January Sep 21 '12 at 14:56
  • I think if we add more answer about creating a custom-shortcut key will improve , what do you say ? – rɑːdʒɑ Sep 21 '12 at 14:57
  • Doesn't work, on my Linux mint mate, instead xdg-screensaver lock works. – user218867 Jun 2 at 12:50
33

In addition to what January said, this also works:

gnome-screensaver-command --lock

or

gnome-screensaver-command -l

According to the gnome-screensaver-command man page...

-l, --lock                 Tells the running screensaver process to lock the screen immediately
-a, --activate             Turn the screensaver on (blank the screen)

For further clarification, here is another question/answer (also by January) which describes the differences between invoking the lock and activating your screensaver:

Difference between gnome-screensaver-command -a and gnome-screensaver-command -l

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20

Starting in Ubuntu 14.04, Unity's lock screen no longer uses gnome-screensaver. The command gnome-screensaver-command -l will still work in most cases, but see this question for exceptions.

If that command does not work (say, for instance, that gnome-screensaver is not installed), bringing up the proper Unity lock screen (not the greeter where you can switch users) can be done via this command in a terminal:

dbus-send --type=method_call --dest=org.gnome.ScreenSaver /org/gnome/ScreenSaver org.gnome.ScreenSaver.Lock
17

Please install vlock. Then you can switch to a VT (text terminal, using Ctrl+Alt+F1) and run

vlock -a -s

This works whether you have X11 running or not.

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    looking nice . ok I'll try and let you know . thank you . – rɑːdʒɑ Sep 14 '12 at 7:14
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    ok its looking good , but suits only for TTY . – rɑːdʒɑ Sep 14 '12 at 12:59
  • Version 2.0.4 of vlock does not seem to have the -s switch anymore. Just running vlock -a works fine. – friederbluemle Nov 27 '17 at 11:08
  • In Version 2.2.2, the s flag exists and is defined as -s or --disable-sysrq: disable SysRq while consoles are locked to prevent killing vlock with SAK. SAK is the secure attention key, which protects against trojan password capturing according to kernel.org. In a tty the a flag is enough to password protect. – Timo May 31 '20 at 4:56
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In case that you need to lock the screen on a terminal in a non-GUI environment you could make use of screen

While in screen press the following key combinations to lock the terminal.

Ctrl + a

Ctrl + x

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  • Thank you . now I'm in mobile . I'll try and let you know – rɑːdʒɑ Sep 12 '12 at 11:00
  • For Tmux, set-option -g lock-command vlock (require vlock) – Bohr Jun 27 '15 at 14:51
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$!(sleep 10s ;  xset dpms force suspend) & xdg-screensaver lock

this starts the screen saver in locked mode and then puts your display in standby. sweet and simple, no sudo. command line or shell script works fine. i use this for a keyboard hotkey. Ubuntu Mate 15.10

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  • Works on Kubuntu 16.04 too. – jippie Oct 23 '16 at 9:52
  • ty for xdg-screensaver lock, +1, however your answer didn't do the trick on ubuntu 16.10 gnome 3, i use: xdg-screensaver lock && sleep 2s && sudo pm-suspend. i have this aliased, and also with pm-suspend in my sudoers.d: yourusername yourhostame = NOPASSWD: /usr/sbin/pm-suspend – zamnuts Jan 3 '17 at 7:52
  • ERROR: Unknown command 'lock' in Lubuntu 18.4. LTs – Timo Jun 5 '20 at 4:20
  • Thank you - this works without installing gnome screen save – Amin Jul 14 '20 at 19:52
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For LightDM users, try dm-tool switch-to-greeter.

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    dm-tool lock seems better as that just locks the screen. "switch to greeter" ended my session when I tried it. – pbhj Sep 7 '15 at 16:19
  • Using this in a cron job does not work? Script : lock_script.sh #!/bin/sh dm-tool switch-to-greeter Cron-job : 42 9 * * * /home/user/lock-script.sh – Dinesh May 4 '17 at 7:43
  • dm-tool is not very safe. Not on my system, anyway. Try going to a text TTY (Alt-Ctrl-F2) then back to your X TTY (Ctrl-Alt-F7 for me). It makes the lock screen disappear! – Rolf May 30 '17 at 15:16
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In my case xdg-screensaver lock is works perfectly fine. Also I save it by the setting or when I press window+L it will lock the screen immediately

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  • holms@debian:~$ xdg-screensaver lock ERROR: Unknown command 'lock' – holms Mar 16 at 22:41
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    This works on Mint mate 20.1, which is based on Ubuntu 20.04. – user218867 Jun 2 at 12:49
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    The accepted answer uses a command that I don't even have installed on Ubuntu 20.04. This one works without installing anything extra. – electrovir Jun 24 at 16:31
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A dirty hack of using the shortcut Ctrl+Alt+L for the locking the screen from a terminal:

  1. Install xdotool from the software center or from the terminal as follows:

    sudo apt-get install xdotool
    
  2. Type the following to lock the screen from the terminal:

    xdotool key Ctrl+alt+l
    

Refer to the manual page for xdotool for more.

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  • This was definitely the best - because the other "screen-saver" based ones gave you a different "lock screen" which ONLY allows you to enter a password (no changer-user, logout, restart, etc). Also: May want to do stuff like: DISPLAY=:0 sudo -u username xdotool key Ctrll+alt+l – Brad Nov 18 '17 at 16:01
  • nothing happens in dwm – holms Mar 16 at 22:41
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It depends on your display manager. I have lightdm, I can do dm-tool lock to bring up a lock screen. It's not really secure, though, I found an easy way to bypass it.

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A similar situation to lock the screen in lubuntu

in lubuntu 17.10 (not ubuntu) this works xset dpms force off

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